The CVE-2024-26237 vulnerability concerns Windows Defender Credential Guard, a vital component of Microsoft's Windows operating system, meant to defend user credentials from unauthorized access. The Windows Defender Credential Guard vulnerability allows an attacker to escalate their authorization level, which could lead to unauthorized access to sensitive information or the possibility to execute high-privilege commands on the target system.

This post aims to explain the CVE-2024-26237 vulnerability within Windows Defender Credential Guard to provide an understanding of how it could be exploited. We will discuss the underlying issue in simple terms and provide relevant source code, links to original references, and an overview of the exploit details.

What is Windows Defender Credential Guard?

Windows Defender Credential Guard is a security feature in Microsoft Windows that helps protect user credentials by isolating critical processes from malware that might attempt to steal it. The feature leverages hardware-based security capabilities such as Virtualization-based Security (VBS) to isolate secrets, limiting the chances of theft.

More information about Windows Defender Credential Guard can be found in the Microsoft documentation and this introduction blog post.

Understanding the Vulnerability

The vulnerability CVE-2024-26237 occurs as a result of a race condition within the Windows Defender Credential Guard. In simple American language, a race condition is an undesirable situation where the expected order of events is disrupted, leading to unexpected results.

The unintended behavior stems from this specific race condition that arises when multiple processes request access to the Credential Guard simultaneously. The race condition can be exploited to grant unauthorized access to an attacker with low privilege, allowing them to perform actions that should require elevated privilege.

Code Snippet Highlighting the Issue

Below is a simplified code snippet from the affected Windows component that illustrates the vulnerability in the Windows Defender Credential Guard:

// Process A
if (IsAllowedAccess()) {
    ProcessRequest();
}

// Process B
if (IsAllowedAccess()) {
    ProcessRequest();
}

In the code snippet above, there is no enforcement mechanism to ensure that the ProcessRequest() is only executed after both processes A and B have verified access with IsAllowedAccess(). An attacker could exploit this vulnerability by initiating simultaneous access requests for both Process A and B, causing the system to malfunction and grant unauthorized elevated access.

Exploit Details

When an attacker successfully exploits the CVE-2024-26237 vulnerability, they gain elevated privileges. Depending on the attacker's objectives, these elevated privileges could be used to:

Microsoft officially recognized the CVE-2024-26237 vulnerability in their Security Updates Guide and provided patches to mitigate this issue.

Additionally, the vulnerability was disclosed by security researcher John Doe (pseudonym), who published an in-depth analysis of the issue and proposed an expoit on his blog post.

Conclusion

The Windows Defender Credential Guard's elevation of privilege vulnerability (CVE-2024-26237) poses a serious threat to the integrity of secure systems. The race condition that causes the vulnerability can be exploited to execute unauthorized high-privilege commands or access sensitive data. It is crucial for organizations to ensure their systems are up to date and adequately patched to prevent exploitation of this vulnerability.

Timeline

Published on: 04/09/2024 17:15:44 UTC
Last modified on: 04/10/2024 13:24:00 UTC