In this long-read post, we will dive deep into a security vulnerability discovered in GitLab CE/EE (Community Edition and Enterprise Edition) that affects multiple versions. The vulnerability, cataloged as CVE-2023-5825, allows a low-privileged attacker to cause a Denial of Service (DoS) attack by exploiting a weakness in the CI/CD Configuration component of GitLab. In essence, the attacker is able to point this component to an incorrect path, which in turn causes the server to enter an infinite loop and exhaust all available memory.

All versions starting from 16.5 before 16.5.1

Now, let's dive into the details of this vulnerability and how it can be exploited.

Exploit Details

Using this vulnerability, an attacker with low-privileged access to the GitLab environment - typically as a developer or guest - is able to manipulate the CI/CD Configuration and point the system to an erroneous path that makes the system consume all available memory. This results in a DoS that renders the system inoperable for all other users.

Here's an example of how the code snippet would look like in a GitLab CI/CD configuration file

stages:
  - loop_stage

loop_job:
  stage: loop_stage
  script:
    - |
      while true; do
        find /some/invalid/path
      done

In this example, the attacker has introduced an infinite loop that runs the find command repeatedly on an invalid path. The /some/invalid/path is a placeholder for a path that would trigger the infinite loop in the target system. Since the path is invalid, the find command will fail to terminate, running indefinitely and consuming all available memory until the server comes to a halt.

Mitigation and Fix

GitLab has released patches for the affected versions that properly address this vulnerability. They are available in the following updated versions:

1. GitLab CE/EE 16.3.6
2. GitLab CE/EE 16.4.2
3. GitLab CE/EE 16.5.1

It is highly recommended that you upgrade to one of these versions to safeguard your GitLab environment from potential attacks. The official GitLab release notes and security blog provide further details about these updates:

- GitLab 16.3.6 Release Notes
- GitLab 16.4.2 Release Notes
- GitLab 16.5.1 Release Notes
- GitLab Security Blog

In conclusion, staying informed about potential vulnerabilities and applying the latest patches as soon as they're released is crucial in maintaining the security of your CI/CD environment. Understanding and being able to identify attack patterns like the one demonstrated in CVE-2023-5825 will help you maintain a proactive and security-conscious mindset.

Timeline

Published on: 11/06/2023 11:15:09 UTC
Last modified on: 11/14/2023 17:00:25 UTC