# Win32 API Execution

## Powershell

### Add-Type

{% hint style="danger" %}
Add-Type calls the csc compiler, which writes to disk. 
{% endhint %}

```powershell
$User32 = @"
using System;
using System.Runtime.InteropServices;
public class User32 {
 [DllImport("user32.dll", CharSet=CharSet.Auto)]
 public static extern int MessageBox(IntPtr hWnd, String text, String caption, int
options);
}
"@
Add-Type $User32
[User32]::MessageBox(0, "This is an alert", "MyBox", 0)
```

### Dynamic Invocation - UnsafeNativeMethods

{% hint style="warning" %}
This snippet's purpose is to demonstrate the concept of Dynamic Invocation, 

For actual operational usage I recommend using this amazing project by TheWover

<https://github.com/TheWover/DInvoke>
{% endhint %}

```powershell
function LookupFunc {
 Param ($moduleName, $functionName)
 $assem = ([AppDomain]::CurrentDomain.GetAssemblies() |
 Where-Object { $_.GlobalAssemblyCache -And $_.Location.Split('\\')[-1].
 Equals('System.dll') }).GetType('Microsoft.Win32.UnsafeNativeMethods')
 $tmp=@()
 $assem.GetMethods() | ForEach-Object {If($_.Name -eq "GetProcAddress") {$tmp+=$_}}
 return $tmp[0].Invoke($null, @(($assem.GetMethod('GetModuleHandle')).Invoke($null,
@($moduleName)), $functionName))
}

function getDelegateType {
 Param (
 [Parameter(Position = 0, Mandatory = $True)] [Type[]] $func,
 [Parameter(Position = 1)] [Type] $delType = [Void]
 )
 
 $type = [AppDomain]::CurrentDomain.
 DefineDynamicAssembly((New-Object 
 System.Reflection.AssemblyName('ReflectedDelegate')),
 [System.Reflection.Emit.AssemblyBuilderAccess]::Run).
 DefineDynamicModule('InMemoryModule', $false).
 DefineType('MyDelegateType', 'Class, Public, Sealed, AnsiClass, AutoClass',
 [System.MulticastDelegate])
 
 $type.
 DefineConstructor('RTSpecialName, HideBySig, Public',
 [System.Reflection.CallingConventions]::Standard, $func).
 SetImplementationFlags('Runtime, Managed')
 
 $type.
 DefineMethod('Invoke', 'Public, HideBySig, NewSlot, Virtual', $delType, $func).
 SetImplementationFlags('Runtime, Managed')
 
 return $type.CreateType()
}

$VirtualAllocAddr = LookupFunc kernel32.dll VirtualAlloc
$VirtualAllocDelegateType = getDelegateType @([IntPtr], [UInt32], [UInt32], [UInt32])
```


---

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