ansicon/injdll32.c
2010-11-08 15:31:01 +10:00

113 lines
3.3 KiB
C

/*
Inject code into the target process to load our DLL. The target thread
should be suspended on entry; it remains suspended on exit.
Initially I used the "stack" method of injection. However, this fails
when DEP is active, since that doesn't allow code to execute in the stack.
To overcome this I used the "CreateRemoteThread" method. However, this
would fail with Wselect, a program to assist batch files. Wselect runs,
but it has no output. As it turns out, removing the suspended flag would
make Wselect work, but it caused problems with everything else. So now I
allocate a section of memory and change the context to run from there. At
first I had an event to signal when the library was loaded, then the memory
was released. However, that wouldn't work with -p and CMD.EXE (4NT v8
worked fine). Since it's possible the DLL might start a process suspended,
I've decided to simply keep the memory.
*/
#include "injdll.h"
#ifdef _WIN64
#include "wow64.h"
TWow64GetThreadContext Wow64GetThreadContext;
TWow64SetThreadContext Wow64SetThreadContext;
#define CONTEXT WOW64_CONTEXT
#undef CONTEXT_CONTROL
#define CONTEXT_CONTROL WOW64_CONTEXT_CONTROL
#define GetThreadContext Wow64GetThreadContext
#define SetThreadContext Wow64SetThreadContext
#endif
DWORD LLA;
void InjectDLL32( LPPROCESS_INFORMATION ppi, LPCSTR dll )
{
CONTEXT context;
DWORD len;
LPVOID mem;
DWORD mem32;
#define CODESIZE 20
BYTE code[CODESIZE+MAX_PATH];
len = lstrlenA( dll ) + 1;
if (len > MAX_PATH)
return;
if (LLA == 0)
{
#ifdef _WIN64
extern HMODULE hKernel;
#define GETPROC( proc ) proc = (T##proc)GetProcAddress( hKernel, #proc )
GETPROC( Wow64GetThreadContext );
GETPROC( Wow64SetThreadContext );
// Assume if one is defined, so is the other.
if (Wow64GetThreadContext == 0)
return;
STARTUPINFO si;
PROCESS_INFORMATION pi;
ZeroMemory( &si, sizeof(si) );
si.cb = sizeof(si);
CopyMemory( code, dll, len - 7 ); // ...ANSI32.dll\0
CopyMemory( code + len - 7, "-LLA.exe", 9 ); // ...ANSI-LLA.exe\0
if (!CreateProcess( (char*)code, NULL, NULL, NULL, FALSE, 0, NULL, NULL,
&si, &pi ))
return;
WaitForSingleObject( pi.hProcess, INFINITE );
GetExitCodeProcess( pi.hProcess, &LLA );
CloseHandle( pi.hProcess );
CloseHandle( pi.hThread );
#else
LLA = (DWORD)GetProcAddress( GetModuleHandleA( "kernel32.dll" ),
"LoadLibraryA" );
#endif
}
CopyMemory( code + CODESIZE, dll, len );
len += CODESIZE;
context.ContextFlags = CONTEXT_CONTROL;
GetThreadContext( ppi->hThread, &context );
mem = VirtualAllocEx( ppi->hProcess, NULL, len, MEM_COMMIT,
PAGE_EXECUTE_READWRITE );
mem32 = (DWORD)(DWORD_PTR)mem;
union
{
PBYTE pB;
PDWORD pL;
} ip;
ip.pB = code;
*ip.pB++ = 0x68; // push eip
*ip.pL++ = context.Eip;
*ip.pB++ = 0x9c; // pushf
*ip.pB++ = 0x60; // pusha
*ip.pB++ = 0x68; // push "path\to\ANSI32.dll"
*ip.pL++ = mem32 + CODESIZE;
*ip.pB++ = 0xe8; // call LoadLibraryA
*ip.pL++ = LLA - (mem32 + (ip.pB+4 - code));
*ip.pB++ = 0x61; // popa
*ip.pB++ = 0x9d; // popf
*ip.pB++ = 0xc3; // ret
WriteProcessMemory( ppi->hProcess, mem, code, len, NULL );
FlushInstructionCache( ppi->hProcess, mem, len );
context.Eip = mem32;
SetThreadContext( ppi->hThread, &context );
}