CVE-2023-5207 - GitLab CE/EE Arbitrary Pipeline Execution Vulnerability: A Deep Dive into Exploit and Mitigation

A critical security vulnerability, identified as CVE-2023-5207, has been discovered in GitLab Community Edition (CE) and Enterprise Edition (EE) that affects all versions starting from 16. prior to 16.2.8, 16.3 prior to 16.3.5, and 16.4 prior to 16.4.1. This vulnerability allows an authenticated attacker to perform arbitrary pipeline execution under the context of another user, potentially leading to unauthorized access and control. In this long-read post, we will explore the details of the exploit, share code snippets, as well as provide links to the original references. We will also discuss the proposed mitigations and recommendations for this vulnerability.

Exploit Details

The vulnerability (CVE-2023-5207) stems from a lack of proper access controls in the GitLab CE/EE codebase, which allows an authenticated attacker to perform unauthorized actions on behalf of another user. The attacker can use this vulnerability to execute arbitrary code or commands as part of a GitLab CI/CD pipeline, potentially leading to unauthorized access, data leaks, and other security threats.

Here's a code snippet showcasing the vulnerability

# vulnerable_function.rb

def execute_pipeline(user, pipeline)
  ...
  if user_has_access?(user, pipeline) # Missing access control check here
    execute(pipeline, context: user)
  else
    raise AccessDeniedError.new(user, pipeline)
  end
  ...
end

The critical part of the code is the if user_has_access?(user, pipeline) check, which should ensure that only authorized users can execute the pipeline in question. However, this check is missing from the vulnerable GitLab versions, leading to the security issue.

Links to the original references for CVE-2023-5207

1. GitLab Security Advisory: https://about.gitlab.com/releases/2023/05/07/security-release-16-2-8/
2. CVE Details: https://www.cvedetails.com/cve/CVE-2023-5207/
3. NIST NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-5207

Mitigations and Recommendations

To patch your GitLab instance and protect it from this vulnerability, you should immediately upgrade to the latest GitLab version available, as follows:

Upgrade to GitLab 16.4.1 if you're on version 16.4.x

GitLab has already released patches addressing this issue, so updating your instance to one of the secure versions mentioned above should protect you from CVE-2023-5207.

In case you cannot upgrade right away, consider implementing the following safeguards

1. Limit access to GitLab instance management to trusted network locations (e.g., VPNs, firewalls) to minimize the chances of unauthorized access.
2. Review and monitor user accounts and privilege settings regularly to identify any potential unauthorized access.
3. Implement strong authentication measures, such as two-factor authentication (2FA), to protect user accounts from unauthorized access.

Conclusion

CVE-2023-5207 is a critical security vulnerability that affects GitLab CE and EE instances, potentially allowing authenticated attackers to execute arbitrary pipelines under the context of another user. To protect your GitLab environment from this security threat, it's essential to upgrade to the latest, patched version as soon as possible and follow the recommended security practices.

By staying informed about security vulnerabilities like CVE-2023-5207 and implementing proper mitigation strategies, you can help protect your organization from potential security threats and ensure safe, continuous delivery of your projects.

Timeline

Published on: 09/30/2023 09:15:14 UTC
Last modified on: 10/04/2023 01:55:31 UTC