Recently, security researchers discovered a critical vulnerability in various versions of GitLab Enterprise Edition (EE). The vulnerability, identified as CVE-2022-4335, affects all versions of GitLab EE prior to 15.4.6, 15.5 prior to 15.5.5, and 15.6 prior to 15.6.1. This exploit, known as a blind Server-Side Request Forgery (SSRF) vulnerability, could allow a malicious actor to connect to a local host and potentially access sensitive information.

This post will provide a detailed analysis of this vulnerability, including an explanation of how it works, relevant code snippets, and links to original references. We will also discuss the potential impact of the exploit, and preventive steps that organizations can take to safeguard their GitLab systems.

Understanding Blind SSRF Vulnerability

A blind SSRF is a type of security flaw where an attacker can force a vulnerable application to make HTTP requests to an arbitrary domain or address. It is considered "blind" because the attacker doesn't receive the response from the server directly. However, even without receiving the server response, the attacker could still cause damage or retrieve sensitive data through various techniques.

In the case of CVE-2022-4335, the GitLab EE application was found to have a feature that allowed unauthenticated users to send arbitrary HTTP requests to any IP address, including the localhost. This vulnerability can allow a malicious actor to bypass security restrictions and connect to internal services running on the local machine.

POST /dependency_proxy/repository HTTP/1.1
Content-Type: application/json
{"url": "http://127...1/example_host";}

This shows an HTTP request sent by an unauthenticated user attempting to exploit the blind SSRF vulnerability. The attacker enters an arbitrary IP address or domain name as the "url" in the JSON payload, targeting the localhost (127...1) in this case.

For further information on this vulnerability, you can refer to the following original references

1. GitLab Security Update
2. CVE-2022-4335 on MITRE's CVE List
3. NIST National Vulnerability Database (NVD) Entry

Exploit Details

The exploit relies on an attacker sending crafted HTTP requests to the GitLab application, targeting the Dependency Proxy feature. By using this feature, an attacker could potentially access sensitive data or cause a denial of service (DoS) by connecting to the local host or localhost and overwhelming system resources.

It is important to note that this vulnerability can be especially dangerous if an organization has not implemented proper network segmentation and firewall settings. An attacker could potentially use this flaw to scan the internal network or access restricted services running within the local network.

To protect your GitLab EE instances from this vulnerability, take the following steps

1. Update your GitLab EE to version 15.4.6, 15.5.5, or 15.6.1, as these versions include security patches that address CVE-2022-4335.
2. Review and apply proper network segmentation and firewall settings to both the GitLab application and any internal resources that it may connect to.
3. If your current version of GitLab cannot be updated immediately, consider restricting access to the Dependency Proxy feature as a temporary measure to mitigate the risk.

It is always essential to keep software up-to-date and maintain a proper security posture to defend against potential vulnerabilities and exploits. With the discovery of CVE-2022-4335, GitLab administrators must promptly update their instances to reduce the risk of a successful compromise.


Published on: 01/27/2023 18:15:00 UTC
Last modified on: 02/06/2023 18:37:00 UTC