lstrcmpA Killer

#include <Windows.h>
#include <tlhelp32.h>
#include <iostream>
using namespace std;

#define MSGRET(str, ret) { cout << "ERROR: " << str << endl; system("pause"); return ret; }

DWORD procNameToPID(const char *procName);
bool dllInjection(DWORD pid, string dll);
void WinAPIError();

int main(int argc, const char *argv[])
{
    DWORD pid = procNameToPID("externalCrackme.exe");

    if (!pid)
        MSGRET("Process not found.", 1)
    cout << "PID Found: " << pid << endl;

    cout << "Killing strcmp..." << endl;

    HANDLE processHandle = OpenProcess(PROCESS_ALL_ACCESS, false, pid);
    if (!processHandle)
        MSGRET("Cannot open process.", false)

    HMODULE kernel32 = GetModuleHandle("Kernel32");
    FARPROC lstrcmpAptr = GetProcAddress(kernel32, "lstrcmpA");

    char data[] = { 0x33, 0xc0, 0xc2, 0x08, 0x00 };

    DWORD oldFlags;
    VirtualProtectEx(processHandle, (void*)lstrcmpAptr, sizeof(data), PAGE_EXECUTE_READWRITE, &oldFlags);
    if (!WriteProcessMemory(processHandle, (void*)lstrcmpAptr, &data, sizeof(data), NULL))
    {
        WinAPIError();
        MSGRET("Could not WriteProcessMemory.", 0)
    }
    VirtualProtectEx(processHandle, (void*)lstrcmpAptr, sizeof(data), oldFlags, &oldFlags);

    system("pause");

    return 0;
}

DWORD procNameToPID(const char *procName)
{
    HANDLE snapshot = CreateToolhelp32Snapshot(TH32CS_SNAPPROCESS, 0);
    if (snapshot == INVALID_HANDLE_VALUE)
        MSGRET("Unable to create snapshot.", 0)

    PROCESSENTRY32 process;
    process.dwSize = sizeof(PROCESSENTRY32);

    Process32First(snapshot, &process);
    do
    {
        if (strstr(process.szExeFile, procName))
            return process.th32ProcessID;
    }
    while (Process32Next(snapshot, &process));

    return 0;
}

void WinAPIError()
{
    LPSTR errorMessage = NULL;
    FormatMessage(FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_ALLOCATE_BUFFER, 0, GetLastError(), 0, (LPSTR)&errorMessage, 0, 0);
    cout << "WinAPI: " << errorMessage;
    LocalFree(errorMessage);
}