checkymander

using System;
using System.Collections.Generic;
using System.DirectoryServices.Protocols;
using System.Globalization;
using System.Linq;
using System.Runtime.InteropServices;
using System.Runtime.InteropServices.ComTypes;
using System.Security.Policy;
using System.Text;
using System.Threading.Tasks;

checkymander

Overview

In the default configuration of Active Directory, it is possible to remotely take over Workstations (Windows 7/10/11) and possibly servers (if Desktop Experience is installed) when their WebClient service is running. This is accomplished in short by;

• Triggering machine authentication over HTTP via either MS-RPRN or MS-EFSRPC (as demonstrated by @tifkin_). This requires a set of credentials for the RPC call.
• Relaying that machine authentication to LDAPS for configuring RBCD
• RBCD takeover

The caveat to this is that the WebClient service does not automatically start at boot. However, if the WebClient service has been triggered to start on a workstation (for example, via some SharePoint interactions), you can remotely take over that system. In addition, there are several ways to coerce the WebClient service to start remotely which I cover in a section below.

checkymander

using System;
using System.Runtime.InteropServices;


namespace API_Hashing
{
    class Program
    {
        [DllImport("kernel32", SetLastError = true, CharSet = CharSet.Ansi)]
        static extern IntPtr LoadLibrary([MarshalAs(UnmanagedType.LPStr)] string lpFileName);

checkymander

#ifndef PATCHLESS_AMSI_H
#define PATCHLESS_AMSI_H

#include <windows.h>

static const int AMSI_RESULT_CLEAN = 0;

PVOID g_amsiScanBufferPtr = nullptr;

unsigned long long setBits(unsigned long long dw, int lowBit, int bits, unsigned long long newValue) {

checkymander

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checkymander

// Copyright (C) 2022 Evan McBroom
// If you are using Visual Studio, you will need to disable the "Edit and Continue" feature.

// Prng based off of Parker Miller's
// "Multiplicative Linear Congruential Generator"
// https://en.wikipedia.org/wiki/Lehmer_random_number_generator
namespace mlcg {
    constexpr uint32_t modulus() {
        return 0x7fffffff;
    }

checkymander

/*!
 *
 * ROGUE
 *
 * GuidePoint Security LLC
 *
 * Threat and Attack Simulation
 * little tip: race condition at the RtlGetCtx so make a rop that sends an event if the rtl call finished
!*/

checkymander

MS-MSDT 0-day Office RCE

MS Office docx files may contain external OLE Object references as HTML files. There is an HTML sceme "ms-msdt:" which invokes the msdt diagnostic tool, what is capable of executing arbitrary code (specified in parameters).

The result is a terrifying attack vector for getting RCE through opening malicious docx files (without using macros).

Here are the steps to build a Proof-of-Concept docx:

1. Open Word (used up-to-date 2019 Pro, 16.0.10386.20017), create a dummy document, insert an (OLE) object (as a Bitmap Image), save it in docx.

checkymander

<Project ToolsVersion="4.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
  <!-- This inline task executes c# code. -->
  <!-- C:\Windows\Microsoft.NET\Framework\v4.0.30319\msbuild.exe SimpleTasks.csproj -->
  <!-- Save This File And Execute The Above Command -->
  <!-- Original Author: Casey Smith, Twitter: @subTee -->
  <!-- Modified by John Baek, @exploitpreacher to use ntqueueapcthread (https://github.com/FuzzySecurity/Sharp-Suite/tree/master/UrbanBishop) -->
  <!-- License: BSD 3-Clause -->
  <Target Name="Hello">
   <ClassExample />
  </Target>

checkymander

Let's turn Any .NET Application into an LOL Bin

We can do this by experimenting with .config files.

Many defenders catch/detect files that are renamed, they do this by matching Original Filename to Process Name

In this example, we don't have to rename anything. We simple coerce a trusted signed app to load our Assembly.

We do this by directing the application to read a config file we provide.