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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:

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.

Certifried combined with KrbRelayUp

Certifried (CVE-2022-26923) gives Domain Admin from non-privileged user with the requirement adding computer accounts or owning a computer account. Kerberos Relay targeting LDAP and Shadow Credentials gives a non-privileged domain user on a domain-joined machine local admin access on (aka owning) the machine. Combination of these two: non-privileged domain user escalating to Domain Admin without the requirement adding/owning computer accounts.

The attack below uses only Windows (no Linux tools interacting with the Domain), simulating a real-world attack scenario.

Prerequisites:

KrbRelay with RBCD Privilege Escalation HOWTO

Short HOWTO about one use case of the work from Cube0x0 (KrbRelay) and others.

TL;DR

No-Fix Local Privilege Escalation from low-priviliged domain user to local system on domain-joined computers.

Prerequisites:

LDAP signing not required on Domain Controller (default!)

PKI Abuse

Some golden links when you are having issues: https://social.technet.microsoft.com/Forums/windows/en-US/96016a13-9062-4842-b534-203d2f400cae/ca-certificate-request-error-quotdenied-by-policy-module-0x80094800quot-windows-server-2008?forum=winserversecurity

Enumerating ADCS On Linux

Download and install Certi

Kerberos cheatsheet

Bruteforcing

With kerbrute.py:

python kerbrute.py -domain <domain_name> -users <users_file> -passwords <passwords_file> -outputfile <output_file>

With Rubeus version with brute module:

	#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) {

	#!/usr/bin/env python3

	"""
	# NOTE, you must change the string below for data you want.
	# This script does not take arguments in its current form. Sorry!
	"""

	from pwn import *

	string = b"foobar"

	#!/usr/bin/env python3

	"""
	# NOTE, you must change the filename below for the rp++ output you want to process.
	# This script does not take arguments in its current form. Sorry!
	"""

	import re

	from pwn import p32, u32

	using System;
	using System.Diagnostics;
	using System.IO;
	using System.Runtime.InteropServices;

	namespace DinjectorWithQUserAPC
	{


	public class Program

	typedef unsigned int DWORD;
	typedef unsigned char BYTE;
	typedef unsigned char * PBYTE;
	typedef DWORD HRESULT;
	typedef unsigned short USHORT;
	typedef unsigned int ULONG;
	typedef unsigned char UCHAR;
	typedef bool BOOL;

	static const DWORD kCurrentMajorVersion = 2;