Advanced DLL Injector

#define _WIN32_WINNT _WIN32_WINNT_WINXP

#include <iostream>
#include <windows.h>
#include <tlhelp32.h>

int gethd()
{
    PROCESSENTRY32 pe32;
    pe32.dwSize = sizeof(pe32);
    HANDLE hProcessSnap = CreateToolhelp32Snapshot(TH32CS_SNAPPROCESS, 0);
    if(hProcessSnap == INVALID_HANDLE_VALUE)
        return -1;
    else
    {
        if(!Process32First(hProcessSnap, &pe32))
            return -2;
        do
        {
            std::cout << pe32.szExeFile << "[" << pe32.th32ProcessID << "]\n";
        }while(Process32Next(hProcessSnap, &pe32));
    }
    return 0;
}

int main()
{
    std::cout << "\n\n+-+-+-+-+-+-+-+-+\n";
    std::cout << "|1|n|j|3|k|t|0|r|\n";
    std::cout << "+-+-+-+-+-+-+-+-+\n\n\n\n";
    switch(gethd())
    {
        case -1:
            std::cout << "CreateToolhelp32Snapshot()";
        break;
        case -2:
            std::cout << "Process32First()";
        break;
        case 0:
        {
            int pid = 0;
            HANDLE hTarget, hThread;
            LPVOID pAddr, vAlloc;
            OPENFILENAME ofn;
            char dllName[256];

            ZeroMemory(&ofn, sizeof(ofn));
            memset(dllName, 0, 256);

            std::cout << "\n\n\nEnter the process PID: ";
            std::cin >> pid;

            hTarget = OpenProcess(PROCESS_ALL_ACCESS, false, pid);
            if(hTarget == INVALID_HANDLE_VALUE)
                std::cout << "hTarget returned " << GetLastError();
            else
            {
                ofn.lStructSize = sizeof(ofn);
                ofn.hwndOwner = FindWindow("ConsoleWindowClass", NULL);
                ofn.lpstrFile = dllName;
                ofn.lpstrFile[0] = '\0';
                ofn.nMaxFile = sizeof(dllName);
                ofn.lpstrFilter = "";
                ofn.nFilterIndex = 1;
                ofn.lpstrInitialDir = "C:\\";
                ofn.Flags = OFN_PATHMUSTEXIST | OFN_FILEMUSTEXIST;
                if(GetOpenFileName(&ofn))
                {
                    pAddr = GetProcAddress(GetModuleHandle("kernel32.dll"), "LoadLibraryA");
                    vAlloc = VirtualAllocEx(hTarget, NULL, strlen(dllName), MEM_RESERVE | MEM_COMMIT, PAGE_READWRITE);

                    if(pAddr == NULL)
                        std::cout << "pAddr returned " << GetLastError();
                    else if(vAlloc == NULL)
                        std::cout << "vAlloc returned " << GetLastError();
                    else
                    {
                        if(!WriteProcessMemory(hTarget, vAlloc, dllName, strlen(dllName), NULL))
                            std::cout << "WriteProcessMemory returned " << GetLastError();

                        if((hThread = CreateRemoteThread(hTarget, NULL, NULL, (LPTHREAD_START_ROUTINE)LoadLibraryA, vAlloc, NULL, NULL)) == NULL)
                            std::cout << "CreateRemoteThread returned " << GetLastError();
                        else
                        {
                            std::cout << "Injected " << dllName;
                            WaitForSingleObject(hThread, WAIT_TIMEOUT);

                        }
                    }
                }
                else
                    std::cout << "Please choose a DLL.";
            }
        }
    }
    VirtualFreeEx(hTarget, vAlloc, NULL, MEM_RELEASE);
    CloseHandle(hTarget);
    std::cin.ignore();
    std::cin.get();
    return 0;
}