#include <Windows.h>
DWORD WINAPI Hook_thread(LPVOID);
DWORD hooked_messegebox = 0;
DWORD APIENTRY DllMain(HMODULE hModule, DWORD ul_reason_for_call, LPVOID lpReserved)
{
	switch (ul_reason_for_call)
	{
	case DLL_PROCESS_ATTACH:
			CreateThread(NULL, NULL, Hook_thread, NULL, NULL, NULL);
	case DLL_THREAD_ATTACH:
	case DLL_THREAD_DETACH:
	case DLL_PROCESS_DETACH:
						break;
	}
	return true;
}
int WINAPI HookedMessegeBox(
	_In_opt_ HWND    hWnd,
	_In_opt_ LPCTSTR lpText,
	_In_opt_ LPCTSTR lpCaption,
	_In_      UINT    uType
)
{
	return MessageBox (hWnd, "Hooked!", "Hooked!", MB_OK | MB_ICONERROR);

}
void CallHook()
{
	_asm call dword ptr hooked_messegebox
}
DWORD WINAPI Hook_thread(LPVOID)
{
	DWORD hooked_messegebox = (DWORD)HookedMessegeBox;
	DWORD call_address = (DWORD)GetProcAddress(GetModuleHandleA("user32.dll"), "MessageBoxA");
	DWORD old_prot = 0;

	VirtualProtect((void*)call_address, 6, PAGE_EXECUTE_READWRITE, &old_prot);

	memcpy((void*)call_address, (PBYTE)CallHook, 6);

	VirtualProtect((void*)call_address, 6, old_prot, &old_prot);

	::ExitThread(1337);
}