Windows 10: Bug in Credential Guard in Windows 11 23H2

Milan Kopáč · Dec 1, 2023

Hi,I experienced a bug in Windows 11 23H2 OS Build: 22631.2715 where I disabled Credential Guard, Hyper-V features on purpose to be able to run Oracle Virtualbox VM on normal performance. When I tried to re-enable Credential Guard and Hyper-V the same way I disabled them I experienced a bug described below:After re-enabling Credential Guard I immediately saw that it is not running. I was not able to use multiple Windows applications OneDrive, Outlook, Whatsapp etc... because I was not able to log in. Even when I was able to log to some apps after restart the apps were unable to log me back

:)

Brink · Dec 1, 2023

Credential Guard lab companion

If you have heard about Credential Guard in Windows Server 2016 (and in Windows 10), but do not have an environment to try it out, here is a lab environment we built for you to play.

Lab access

The link will lead you to a sign up page, after that, you will see the following labs listed for Windows Server 2016:

Windows Server 2016 labs

There are 3 exercises in the “Implementing Breach Resistance Security in Windows Server 2016”:

Credential Guard

Remote Credential Guard

Device Guard

This blogpost will walk you through the Credential Guard lab details.

After click on the link of Breach Resistance lab, you be required to sign in and then you can launch the lab:

Sign-in

Launch page

It takes a few minutes to create the VMs, and once it has done, you will see the following machines prepared:

Initialize

DC: domain controller, which is not used for this exercise.

SRV01 and SRV02: both are Windows Server 2016, and used for the lab exercise.

Lab exercise – Explained

The steps are listed in the Content section:

Content

This lab is structured to cover the following in sequence:

Understand how attackers can use the hash in memory to gain access to domain controllers

Configure Credential Guard

Verify the hash in memory is protected using Credential Guard

You can follow the steps listed under the content section to complete the lab, the intent of the blog, is to break the procedures into groups, to help you understand the exercise better.

Prep the hash

Lsass.exe is the process which handles user logon, it stores the user credential information in its memory. The memory is cleared when the machine starts up. In this lab environment, all the virtual machines start at the time lab launches, when you logon to the machine, you will only have the logon user credential information in memory. In order to demonstrate an attacker gaining user access using other account’s hash, the first part of the lab is to simulate a server which has been running for a while, different users had remotely or locally connected to it, therefore, lsass memory stored many different user credential information.
This is accomplished by step 1-8.

Retrieving credential hash

Mimikatz is a popular tool for retrieving lsass memory information. The tool has been copied to the lab machines, step 9-13 walk you through the process of dumping lsass memory using Mimikatz.

Pass the Hash

Pass the hash is a hacking technique that allows an attacker to authenticate by using the underlying NTLM, instead of specifying the user password. In step 14 to 24, you will extract LabAdmin hash from lsass using Mimikatz, and use the hash to open a PowerShell console, and perform a couple of operations using the LabAdmin privilege:

Add a user to the domain admin group

Open remote PowerShell connection to a domain controller

Both operations could not be performed by the logon user. But using the hash of the LabAdmin, an attacker will be able to do it using the information retrieve from Lsass memory.

Configure and verify Credential Guard

Step 25 to 36 illustrate the steps to configure credential guard, then verify its status using msinfo32.exe and PowerShell.

Step 37 to 43 goes further to use Mimikatz to show the hash in Lsass is now encrypted using Credential Guard.

More info

The exercise illustrated the benefit of Credential Guard in Windows Server 2016 as well as Windows 10. For more information, you can find here.
Click to expand...

Source: Credential Guard lab companion Datacenter and Private Cloud Security Blog

See also:

Enable or Disable Credential Guard in Windows 10 Windows 10 Security System Tutorials

Verify if Credential Guard is Enabled or Disabled in Windows 10 Windows 10 Security System Tutorials

Teo Lachev · Dec 1, 2023

How to disable Windows 11 Defender Credential Guard?

After upgrading to Windows 11 2022H2, RDP always prompts for credentials and Edge Dev doesn't autofill credentials. According to this, Windows 11 H2 enables Windows Defender Credential Guard. I tried to follow the steps to disable it in the Group Policy Editor (it was set to Not Configured) and rebooted, but it doesn't help. How to resolve this scourge?

BTW, shouldn't we enable such features by default and leaving users to figure out to restore the old behavior for hours, instead of asking on install?

Lord_StarPaul86 · Dec 1, 2023

Credential guard not running

yes. now Credential Guard is working fine. I was wrong it`s not 23h2 yet it`s just the moment 4 update with the newest features. But now I noticed the issue with the phishing protection is back again. That it deactivates everytime after the system reboot

Windows 10: Bug in Credential Guard in Windows 11 23H2

Bug in Credential Guard in Windows 11 23H2

Bug in Credential Guard in Windows 11 23H2

Bug in Credential Guard in Windows 11 23H2

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