CVE-2023-3205 - GitLab DoS Vulnerability in Multiple Versions due to Malicious Content Import or Clone

A recent vulnerability has been discovered in GitLab, a widely used web-based Git repository manager that provides source code management (SCM), continuous integration, and continuous deployment pipeline (CI/CD) features. This vulnerability, assigned the ID CVE-2023-3205, affects all GitLab versions starting from 15.11 before 16.1.5, all versions starting from 16.2 before 16.2.5, and all versions starting from 16.3 before 16.3.1. When exploited by an attacker, this vulnerability could trigger a denial of service (DoS) attack when importing or cloning malicious content. This post aims to provide an in-depth explanation of the vulnerability, including its potential impact, code snippets, and how you can protect your systems from exploitation.

Exploit Details

The vulnerability, CVE-2023-3205, allows an authenticated user to trigger a denial of service attack when importing or cloning malicious content. The exploit occurs when the server-side process responsible for importing or cloning a repository encounters specially crafted content and fails to handle it properly, leading to resource exhaustion and causing GitLab services to become unavailable for a period of time.

Though technical details of the exploit have not been made public, the general concept involves sending a request to either import or clone a repository containing malicious content that cannot be safely processed by GitLab. Below is a generic code snippet of how an attacker might trigger the vulnerability:

POST /user/repo/import HTTP/1.1
Host: gitlab.example.com
Content-Type: application/json
Authorization: Bearer <access_token>

{
     "repo_url": "https://malicious.example.com/malicious-repository.git";
} 

In this example, the attacker sends a POST request to GitLab's import API, specifying a malicious repository URL to be imported.

Original References

GitLab has acknowledged the vulnerability and has released patches to address the issue. Detailed information about the vulnerability and its patches can be found in the following resources:

- GitLab's official security release: https://about.gitlab.com/releases/2023/04/01/critical-security-release-gitlab-16-3-1-released/
- CVE-2023-3205 entry in the National Vulnerability Database (NVD): https://nvd.nist.gov/vuln/detail/CVE-2023-3205

Mitigation and Prevention

To protect your systems from this vulnerability, it is highly recommended that you update your GitLab installation to the latest patched version (16.3.1 or later) as soon as possible. The following steps outline how to update your GitLab instance:

1. Review the GitLab update documentation for your specific installation method: https://docs.gitlab.com/ee/update/
2. Ensure you have the latest security patches by following the appropriate upgrade guide for your instance.
3. Verify that the updated version is in use: you can do this by checking the version in the lower-left corner of your GitLab web interface, or by accessing the /help page.

In addition to updating GitLab, you should consider implementing other security best practices, such as:

Monitoring GitLab logs for signs of unusual activity.

- Keeping your server's operating system and other software up to date with the latest security patches.

Conclusion

CVE-2023-3205 is a critical vulnerability affecting multiple GitLab versions. By exploiting this issue, an authenticated attacker can cause a denial of service attack, potentially impacting the availability of GitLab services to other users. To protect your systems, it is essential to apply the latest security patches as soon as possible and adhere to recommended security practices.

Timeline

Published on: 09/01/2023 11:15:00 UTC
Last modified on: 09/01/2023 21:13:00 UTC