/// <summary>
/// Injects a dll into a process by hijacking the given thread and redirecting it to LoadLibrary.
/// </summary>
/// <param name="hProcess">Handle to process into which dll will be injected.</param>
/// <param name="hThread">Handle to thread that will be hijacked.</param>
/// <param name="szDllPath">Full path to the dll to be injected.</param>
/// <returns>Returns the base address of the injected dll on success, zero on failure.</returns>
public static uint InjectDllRedirectThread(IntPtr hProcess, IntPtr hThread, string szDllPath)
{
const uint INITIAL_EXIT_CODE = 0xFFFFFFFF;
if (hProcess == IntPtr.Zero)
{
throw new ArgumentNullException("hProcess");
}
if (hThread == IntPtr.Zero)
{
throw new ArgumentNullException("hThread");
}
if (szDllPath.Length == 0)
{
throw new ArgumentNullException("szDllPath");
}
if (!szDllPath.Contains("\\"))
{
szDllPath = System.IO.Path.GetFullPath(szDllPath);
}
if (!System.IO.File.Exists(szDllPath))
{
throw new ArgumentException("DLL not found.", "szDllPath");
}
uint dwBaseAddress = RETURN_ERROR;
uint lpLoadLibrary, lpAsmStub;
CONTEXT ctx;
StringBuilder AssemblyStub = new StringBuilder();
ManagedFasm fasm = new ManagedFasm(hProcess);
lpLoadLibrary = (uint)Imports.GetProcAddress(Imports.GetModuleHandle("kernel32.dll"), "LoadLibraryA");
if (lpLoadLibrary == 0)
{
return(RETURN_ERROR);
}
lpAsmStub = SMemory.AllocateMemory(hProcess);
if (lpAsmStub == 0)
{
return(RETURN_ERROR);
}
if (SThread.SuspendThread(hThread) != uint.MaxValue)
{
ctx = SThread.GetThreadContext(hThread, CONTEXT_FLAGS.CONTEXT_CONTROL);
if (ctx.Eip > 0)
{
try
{
//located at lpAsmStub+0, where we can monitor LoadLibrary's exit code.
fasm.AddLine("lpExitCode dd 0x{0:X}", INITIAL_EXIT_CODE);
//lpAsmStub+4, where the actual code part starts
fasm.AddLine("push 0x{0:X}", ctx.Eip);
fasm.AddLine("pushad");
fasm.AddLine("push szDllPath");
fasm.AddLine("call 0x{0:X}", lpLoadLibrary);
fasm.AddLine("mov [lpExitCode], eax");
fasm.AddLine("popad");
fasm.AddLine("retn");
//dll path
fasm.AddLine("szDllPath db \'{0}\',0", szDllPath);
fasm.Inject(lpAsmStub);
}
catch
{
SMemory.FreeMemory(hProcess, lpAsmStub);
SThread.ResumeThread(hThread);
return(RETURN_ERROR);
}
ctx.ContextFlags = CONTEXT_FLAGS.CONTEXT_CONTROL;
ctx.Eip = lpAsmStub + 4; //skip over lpExitCode data
if (SThread.SetThreadContext(hThread, ctx))
{
if (SThread.ResumeThread(hThread) != uint.MaxValue)
{
for (int i = 0; i < 400; i++)
{
System.Threading.Thread.Sleep(5);
if ((dwBaseAddress = SMemory.ReadUInt(hProcess, lpAsmStub)) != INITIAL_EXIT_CODE)
{
break;
}
}
}
}
}
}
if (fasm != null)
{
fasm.Dispose();
fasm = null;
}
SMemory.FreeMemory(hProcess, lpAsmStub);
return(dwBaseAddress);
}
/// <summary>
/// Resumes execution of a thread.
/// </summary>
/// <param name="hThread">Handle to the thread to be suspended.</param>
/// <returns>Returns true on success, false on failure.</returns>
public bool ResumeThread(IntPtr hThread)
{
return((SThread.ResumeThread(hThread) == uint.MaxValue) ? false : true);
}