ansicon/injdll32.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 "ansicon.h"

#ifdef _WIN64
#ifndef WOW64_CONTEXT_ALL
#include "wow64.h"

TWow64GetThreadContext Wow64GetThreadContext;
TWow64SetThreadContext Wow64SetThreadContext;
#define IMPORT_WOW64
#endif

#define CONTEXT 	 WOW64_CONTEXT
#undef	CONTEXT_CONTROL
#define CONTEXT_CONTROL  WOW64_CONTEXT_CONTROL
#define GetThreadContext Wow64GetThreadContext
#define SetThreadContext Wow64SetThreadContext

extern
#endif
DWORD LLW32;


void InjectDLL32( LPPROCESS_INFORMATION ppi, LPCTSTR dll )
{
  CONTEXT context;
  DWORD   len;
  LPVOID  mem;
  DWORD   mem32;
  #define CODESIZE 20
  BYTE	  code[CODESIZE+TSIZE(MAX_PATH)];
  union
  {
    PBYTE  pB;
    PDWORD pL;
  } ip;

#ifdef IMPORT_WOW64
  if (Wow64GetThreadContext == 0)
  {
    #define GETPROC( proc ) proc = (T##proc)GetProcAddress( hKernel, #proc )
    HMODULE hKernel = GetModuleHandle( L"kernel32.dll" );
    GETPROC( Wow64GetThreadContext );
    GETPROC( Wow64SetThreadContext );
    // Assume if one is defined, so is the other.
    if (Wow64GetThreadContext == 0)
    {
      DEBUGSTR( 1, L"Failed to get pointer to Wow64GetThreadContext." );
      return;
    }
  }
#endif

  len = TSIZE(lstrlen( dll ) + 1);
  if (len > TSIZE(MAX_PATH))
    return;

  if (LLW32 == 0)
  {
#ifdef _WIN64
    STARTUPINFO si;
    PROCESS_INFORMATION pi;
    ZeroMemory( &si, sizeof(si) );
    si.cb = sizeof(si);
    // ...ANSI32.dll\0
    CopyMemory( code, dll, len - TSIZE(7) );
    // ...ANSI-LLW.exe\0
    CopyMemory( code + len - TSIZE(7), L"-LLW.exe", TSIZE(9) );
    if (!CreateProcess( (LPCTSTR)code, NULL, NULL, NULL, FALSE, 0, NULL, NULL,
			&si, &pi ))
    {
      DEBUGSTR( 1, L"Failed to execute \"%s\".", (LPCTSTR)code );
      return;
    }
    WaitForSingleObject( pi.hProcess, INFINITE );
    GetExitCodeProcess( pi.hProcess, &LLW32 );
    CloseHandle( pi.hProcess );
    CloseHandle( pi.hThread );
#else
    LLW32 = (DWORD)GetProcAddress( GetModuleHandle( L"kernel32.dll" ),
						     "LoadLibraryW" );
#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;

  ip.pB = code;

  *ip.pB++ = 0x68;			// push  eip
  *ip.pL++ = context.Eip;
  *ip.pB++ = 0x9c;			// pushf
  *ip.pB++ = 0x60;			// pusha
  *ip.pB++ = 0x68;			// push  L"path\to\ANSI32.dll"
  *ip.pL++ = mem32 + CODESIZE;
  *ip.pB++ = 0xe8;			// call  LoadLibraryW
  *ip.pL++ = LLW32 - (mem32 + (DWORD)(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 );
}