YAPI -- Yet Another Process Injector

A fusion injector that reduce differences between x64, wow64 and x86 processes according to Mr.Rewolf's article.

Keywords: HEADER-ONLY, DLL-FREE, ANY-CALLEE, ANY-CALLER, ANY-WIN-OS, LOCAL-LIKE

Wiki

• Wow64: Windows-on-Windows 64-bit, which 32-bit process works in.

Features

• Cross x86 & x64 injection without any external *.dll or even *.lib:

  • x86 injector -> x86 process @ 32-bit OS
  • wow64 injector -> wow64 process @ 64-bit OS
  • wow64 injector -> x64 process @ 64-bit OS
  • x64 injector -> wow64 process @ 64-bit OS
  • x64 injector -> x64 process @ 64-bit OS

• In-process call x64 functions / APIs for Wow64 process

• Local-like remote call of target process

  • Remote call multi-params (more than one) windows API of target process
  • Remote call windows API that return 64-bit result of target process

How to use

• X64Call example (Unload dll in remote process)

   X64Call RtlCreateUserThread("RtlCreateUserThread");
  // Validate RtlCreateUserThreadif (!RtlCreateUserThread) return0;
  X64Call LdrUnloadDll("LdrUnloadDll");
  // Validate LdrUnloadDllif (!LdrUnloadDll) return0;
  // => local-like callDWORD64 ret = RtlCreateUserThread(hProcess, NULL, FALSE, 0, 0, NULL, LdrUnloadDll, dllBaseAddr, NULL, NULL);

  • Available constructors:

    • Specified module is allowed (ntdll.dll as default)

      X64Call(constchar* funcName);
      X64Call(DWORD64module, constchar* funcName);

• YAPICall example (MessageBox in remote process)

   YAPICall MessageBoxA(hProcess, _T("user32.dll"), "MessageBoxA");
  // => local-like callMessageBoxA(NULL, "MessageBoxA : Hello World!", "From ez8.co", MB_OK);
  YAPI(hProcess, _T("user32.dll"), MessageBoxW)
  (NULL, L"MessageBoxW: Hello World!", L"From ez8.co", MB_OK);

  • Available constructors:

    • Specified module or module name is allowed (ntdll.dll as default).

    • NOTICE: If failed to fetch 64-bit module, will automatically fetch 32-bit modules in wow64 process under 64-bit OS.

      YAPICall(HANDLE hProcess, constchar* funcName);
      YAPICall(HANDLE hProcess, DWORD64 moudle, constchar* funcName);
      YAPICall(HANDLE hProcess, constTCHAR* modName, constchar* funcName);

• 64-bit result example (GetModuleHandle of user32.dll under 64-bit OS)

   YAPICall GetModuleHandle(hProcess, _T("kernel32.dll"), sizeof(TCHAR) == sizeof(char) ? "GetModuleHandleA" : "GetModuleHandleW");
  DWORD64 user32Dll = GetModuleHandle.Dw64()(_T("user32.dll"));

• Timeout example (GetCurrentProcessId in 300ms)

   YAPICall GetCurrentProcessId(hProcess, _T("kernel32.dll"), "GetCurrentProcessId");
  DWORD pid = GetCurrentProcessId.Timeout(300)();

• Timeout & 64-bit result example (GetModuleHandle in 300ms)

  DWORD64 user32Dll = GetModuleHandle.Dw64().Timeout(300)(_T("user32.dll"));

• Popular LoadLibrary example

   YAPICall LoadLibraryA(hProcess, _T("kernel32.dll"), "LoadLibraryA");
  DWORD64 x86Dll = LoadLibraryA("D:\\x86.dll");
  DWORD64 x64Dll = LoadLibraryA.Dw64()("D:\\x64.dll");
  _tprintf(_T("X86: %I64x\nX64: %I64x\n"), x86Dll, x64Dll);

• API List:

  API Name	x86 Equivalent	Notes
  GetNtDll64
  GetModuleHandle64	GetModuleHandle	overloaded version
  GetProcAddress64	GetProcAddress	overloaded version
  SetLastError64	SetLastError
  VirtualQueryEx64	VirtualQueryEx
  VirtualAllocEx64	VirtualAllocEx
  VirtualFreeEx64	VirtualFreeEx
  VirtualProtectEx64	VirtualProtectEx
  ReadProcessMemory64	ReadProcessMemory
  WriteProcessMemory64	WriteProcessMemory
  LoadLibrary64	LoadLibrary
  CreateRemoteThread64	CreateRemoteThread

• Class List:

  Class Name	32-bit OS Support	64-bit OS Compatiblity
  X64Call	✅	NOT READY NOW
  ProcessWriter	✅	✅
  YAPICall	✅	✅

Inside principle

• Nomal x64->x64, x86->x86 injection:

  • Use CreateRemoteThread / RtlCreateUserThread
  • You can change other methods by yourself.
  • FYR: fdiskyou/injectAllTheThings

• Multi-params windows API:

  • Pack function address and params in one structure and use shell code to execute in remote process.
  • See X86/X64Delegator_disassemble for details in disassemble directory.

• x64 call for wow64 process:

  • Switch to x64 mode
  • See references for details.

• x64 process inject to wow64 process:

  • Use trampoline:
    • CreateRemoteThread(x64): x64 shell code with x86 mode switch (1 arg: function->x86 shell code with one param, param->packed x86 structure) -> pass packed structure (x86 real to call function address and params) to x86 shell code -> pass params to real function.
  • NOTICE: function address(target module) should be valid in target process, but not needed in source injector.

• 64-bit result:

  • Add a DWORD64 result field to package.
  • Obtain result if needed.
  • ReadProcessMemory after remote thread finished.

Compatibility

• Operating systems that have been tested are shown in table below.

  Operating System	Notes
  Windows 10	Tested on 64-bit, should also work on 32-bit
  Windows 8	Should work on both 64-bit and 32-bit
  Windows 7	Tested on 64-bit, should also work on 32-bit
  Windows Vista	Should work on both 64-bit and 32-bit
  Windows XP	Should work on both 64-bit and 32-bit

References

• Mixing x86 with x64 code @rewolf

Roadmap

• More simple impl of X64Call.
• 64-bit OS compatible support of X64Call.
• Finish shell codes that more than 6 arguments for YAPICall.
• Support to fetch specified bit module for YAPICall (32-bit or 64-bit).
• Same function call (mirror call) automatically in remote process.
• Self-defined function call in remote process.
• IAT/inline hook in remote process.
• Support other 7 optional inject methods.

Sponsors

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Contributors

This project exists thanks to all the people who contribute.

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And thank you to all our backers! 🙏

Misc

• Please feel free to use yapi.
• Looking forward to your suggestions.