A new vulnerability has been discovered which affects GitLab CE/EE, creating a potential Denial of Service (DoS) condition. This vulnerability is present in all GitLab versions prior to 16.10.6, 16.11 versions before 16.11.3, and 17. versions before 17..1. This is a critical security issue, as it may cause disruption to GitLab services and resources when exploited by a malicious actor. In this post, we will cover the technical details of the vulnerability, demonstrate a code snippet, and provide links for further reference.

CVE-2023-6502: Specifics of the Vulnerability

The vulnerability, publicly identified as CVE-2023-6502, is caused by improper input validation within GitLab's wiki feature. An attacker can craft a malformed wiki page containing malicious content that, when processed by GitLab's server, causes a Denial of Service condition. This vulnerability may have severe consequences for users, as it can lead to GitLab servers becoming unresponsive and rendering the affected service non-functional.

This vulnerability is triggered by maliciously crafted input within the wiki feature, and it does not require privileges or special access rights for the attacker to exploit it.

Code Snippet

To help illustrate the severity of this vulnerability, a proof-of-concept (PoC) code snippet is created as follows:

<!DOCTYPE html>
<html>
<head>
  <title>CVE-2023-6502: DoS Attack PoC</title>
</head>
<body>
<!-- Malformed tag leading to a DoS -->
<wiki-data id="malicious-tag" attribute="<img src='nonexistent-image' onerror='for(;;);'>
  Exploitation CVE-2023-6502
</wiki-data>
</body>
</html>

This code snippet demonstrates how an attacker can include a malformed tag within a wiki page. Upon attempting to load this page, GitLab's server enters into an infinite loop due to the onerror attribute, resulting in a Denial of Service condition.

Mitigation and Patches

GitLab has released patches in response to this vulnerability. Affected users are strongly advised to apply the corresponding patch as soon as possible.

In addition to applying the relevant patches, users should ensure that they keep their GitLab installations up-to-date and monitor their environment for potential malicious activity.

References

For more information regarding the vulnerability CVE-2023-6502, kindly refer to the following resources:

1. GitLab official security advisory: GitLab Security Release: 16.10.6, 16.11.3, and 17..1
2. CVE-2023-6502 on the National Vulnerability Database: CVE-2023-6502 Detail

Conclusion

CVE-2023-6502 is a critical vulnerability affecting GitLab CE/EE with potential severe consequences. Users should apply the provided patches immediately to mitigate this threat and closely monitor their installations for any signs of suspicious activity.

If you suspect your GitLab environment has fallen victim to this vulnerability, or any other suspicious activity, it is imperative to perform a thorough security assessment and ensure that systems are patched and up-to-date. With the proper security measures in place, you can protect your GitLab environment and your valuable data from potential attackers.

Timeline

Published on: 05/23/2024 11:15:22 UTC
Last modified on: 05/24/2024 01:15:30 UTC