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Index > Windows > EOFEXTRACT - Function for extract the EOF of a file .exe

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krackwar



Joined: 24 May 2008
Posts: 13
Location: Chile
krackwar 15 Mar 2009, 22:08
EOF = END OF FILE
Code:
;@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
;@                                     @
;@   EOFEXTRACT by krackwar            @
;@   krackwar@hotmail.com              @
;@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
include 'win32ax.inc'
.code
start:
stdcall EOFEXTRACT,"C:\archivo.exe"
xor ebx,ebx
mov ebx,eax
 invoke GlobalAlloc,GPTR,4
push eax
invoke wsprintf,eax,"0x%x",ebx
pop eax
push eax
invoke MessageBox,0,eax,"EOF data",0
pop eax
 
invoke GlobalFree,eax
invoke ExitProcess,0
proc EOFEXTRACT,ruta
 locals
    DireccionPE dd ?
    bUsados dd ?
    PE dd ?
    NumeroSecciones dd ?
    BeginLastSection   dd ?
    hFile   dd ?
    EOF dd ?
    tamAr   dd ?
    PointerToRawData dd ?
    IB      dd ?
    SizeOfRawData dd ?
 endl
invoke  CreateFile, [ruta], GENERIC_READ, 0, 0, OPEN_EXISTING, 0, 0
mov [hFile], eax
invoke  GetFileSize, [hFile], 0
mov [tamAr], eax
invoke  GlobalAlloc, GPTR, eax
mov [IB], eax
invoke  ReadFile, [hFile], [IB], [tamAr], addr bUsados, 0
mov ebx ,[IB]
add ebx, 0x3c
mov eax,dword[ebx]
mov [DireccionPE] ,eax
xor ebx,ebx
mov ebx,[IB]
add ebx,eax
mov [PE],ebx
add ebx,0x6
xor edx,edx
mov dx,word[ebx]
mov [NumeroSecciones],edx
mov eax,$28
mov ebx,[NumeroSecciones]
dec ebx
mul ebx
xor edx,edx
mov edx,[DireccionPE]
add edx,$F8
add edx,eax
mov [BeginLastSection],edx
xor eax,eax
xor ebx,ebx
xor edx,edx
mov eax,[IB]
mov edx,[BeginLastSection]
add eax,edx
add eax,16
mov ebx,DWORD[eax]
mov [SizeOfRawData],ebx
add eax,4
xor ebx,ebx
mov ebx,DWORD[eax]
mov [PointerToRawData],ebx
xor ebx,ebx
xor eax,eax
mov  edx, [PointerToRawData]
mov ebx,[SizeOfRawData]
add ebx,edx
mov [EOF],ebx
mov eax,[EOF]
ret
endp
 
.end start
    
Post 15 Mar 2009, 22:08
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Grom PE



Joined: 13 Mar 2008
Posts: 114
Location: i@grompe.org.ru
Grom PE 16 Mar 2009, 00:22
I think you mean overlay offset of PE file.
Post 16 Mar 2009, 00:22
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f0dder



Joined: 19 Feb 2004
Posts: 3175
Location: Denmark
f0dder 16 Mar 2009, 02:12
And there's a big difference.

Personally, for storing legitimate data at the end of an exe, I use an 8-byte (magic,offset) header at the end of the exe
Post 16 Mar 2009, 02:12
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comrade



Joined: 16 Jun 2003
Posts: 1150
Location: Russian Federation
comrade 16 Mar 2009, 03:03
How do digital signatures work?
Post 16 Mar 2009, 03:03
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f0dder



Joined: 19 Feb 2004
Posts: 3175
Location: Denmark
f0dder 16 Mar 2009, 03:24
comrade wrote:
How do digital signatures work?
Good question.

I think the PE-exe variant is to include it as a special PE resource, and exclude the section-with-digital-signature-in from hash/verification?

_________________
carpe noctem
Post 16 Mar 2009, 03:24
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