CVE-2023-3909 : Exploit Details and Defense Strategies

An uncontrolled resource consumption vulnerability has been identified in GitLab, affecting versions ranging from 12.3 to 16.5.1. This vulnerability allows for a Regular Expression Denial of Service by inserting a large string in the timeout input of the gitlab-ci.yml file.

Understanding CVE-2023-3909

This section will delve into the details of CVE-2023-3909, its impact, technical description, affected systems, exploitation mechanism, and mitigation strategies.

What is CVE-2023-3909?

CVE-2023-3909 is an uncontrolled resource consumption vulnerability in GitLab, which could lead to a Regular Expression Denial of Service attack. The vulnerability exists in versions between 12.3 and 16.5.1 of GitLab software.

The Impact of CVE-2023-3909

This vulnerability could be exploited by an attacker to trigger a denial of service condition, causing GitLab services to become unresponsive. This could lead to disruption of services and potential downtime for affected systems.

Technical Details of CVE-2023-3909

Let's explore the technical aspects of CVE-2023-3909, including the vulnerability description, affected systems, and the exploitation mechanism.

Vulnerability Description

The vulnerability stems from uncontrolled resource consumption, specifically in the timeout input of the gitlab-ci.yml file. By injecting a large string into this input, an attacker could cause a Regular Expression Denial of Service, impacting the availability of GitLab services.

Affected Systems and Versions

GitLab versions starting from 12.3 before 16.3.6, 16.4 before 16.4.2, and 16.5 before 16.5.1 are vulnerable to this uncontrolled resource consumption issue. Users utilizing these versions are at risk of exploitation.

Exploitation Mechanism

To exploit CVE-2023-3909, an attacker would need to craft a large string and insert it into the timeout input of the gitlab-ci.yml file. This input could then trigger the Regular Expression Denial of Service condition, leading to service disruption.

Mitigation and Prevention

Mitigating CVE-2023-3909 requires immediate action to address the vulnerability and prevent potential exploitation. Here are some steps for remediation and long-term security practices:

Immediate Steps to Take

Upgrade to GitLab versions 16.5.1, 16.4.2, or 16.3.6, which contain fixes for the vulnerability.
Review and adjust the configurations related to the gitlab-ci.yml file to prevent unauthorized input.

Long-Term Security Practices

Regularly update GitLab software to the latest versions to ensure all security patches are applied promptly.
Conduct regular security assessments and audits to identify and address vulnerabilities proactively.

Patching and Updates

GitLab has released patches for CVE-2023-3909 in versions 16.5.1, 16.4.2, and 16.3.6. It is essential for users to update their GitLab installations to these patched versions to mitigate the risk of exploitation and enhance the security posture of their systems.