Can't load custom DLL

Question

I created a simple DLL that open cmd.exe.

I did it with these options:

In the default dlllmain.cpp I added a code that creates a new cmd.exe:

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

BOOL APIENTRY DllMain( HMODULE hModule,
                       DWORD  ul_reason_for_call,
                       LPVOID lpReserved
                     )
{
    switch (ul_reason_for_call)
    {
    case DLL_PROCESS_ATTACH:
    {
        STARTUPINFO info = { sizeof(info) };
        PROCESS_INFORMATION processInfo;
        BOOL h = CreateProcessW(L"C:\\Windows\\System32\\cmd.exe", L"", NULL, NULL, TRUE, 0, NULL, NULL, &info, &processInfo);
    }
    case DLL_THREAD_ATTACH:
    case DLL_THREAD_DETACH:
    case DLL_PROCESS_DETACH:
        break;
    }
    return TRUE;
}

These three lines below the DLL_PROCESS_ATTACH worked for me when I tested it with a console application.

I am expecting that every process that will load this DLL will open cmd.exe.

I tried to load the DLL with PowerShell:

Add-Type -TypeDefinition @"
    using System;
    using System.Diagnostics;
    using System.Runtime.InteropServices;

    public static class Kernel32
    {
        [DllImport("kernel32", SetLastError=true, CharSet = CharSet.Ansi)]
            public static extern IntPtr LoadLibrary(
                [MarshalAs(UnmanagedType.LPStr)]string lpFileName); 
} 


"@

    $LibHandle = [Kernel32]::LoadLibrary("C:\tmp\myDll.dll")

But nothing happens, the value of the $LibHandle was 0.

What I am doing wrong ?

Answer 1

I found what was the problem.
My system is 64 bit and the file was compiled in 32 bit.
I needed to specify in Visual Studio that I am compiling it in x64 bit.

I didn't check it in the beginning because I thought that when I am compiling it on "Any CPU" mode, it compile the file in 64 bit automatically as the OS architecture.

Now it works fine.