VEHHook NoClass

vehhook_nc.cpp

// Credits to @MarkHC
#include <cstdio>
#include <Windows.h>

int add(int a, int b)
{
    return a + b;
}

int mul(int a, int b)
{
    return a * b;
}

LONG WINAPI VectoredExceptionHandle(PEXCEPTION_POINTERS peInfo)
{
    printf("Found exception 0x%X\n", peInfo->ExceptionRecord->ExceptionCode);

    if (peInfo->ExceptionRecord->ExceptionCode == EXCEPTION_BREAKPOINT)
    {
        peInfo->ContextRecord->Eip = (DWORD_PTR)&mul;
        return EXCEPTION_CONTINUE_EXECUTION;
    }
    return EXCEPTION_CONTINUE_SEARCH;
}

int main()
{
    AddVectoredExceptionHandler(1, VectoredExceptionHandle);
    printf("%d != %d\n", add(3, 4), mul(3, 4));

    printf("%d == ", add(4, 5));

    BYTE origByte = *(BYTE*)&add;
    DWORD dwOld;
    VirtualProtect(&add, 1, PAGE_EXECUTE_READWRITE, &dwOld);
    *(BYTE*)&add = 0xCC;    // INT3 Breakpoint
    printf("%d\n", add(4, 5));
    *(BYTE*)&add = origByte;
    VirtualProtect(&add, 1, dwOld, &dwOld);    

    printf("%d != %d\n", add(3, 4), mul(3, 4));    

    system("Pause");
    return 0;
}