CVE-2023-35133 : Security Advisory and Response

An issue in the logic used to check 0.0.0.0 against the cURL blocked hosts lists resulted in an SSRF risk in Moodle versions 4.2 and earlier. Learn about the impact, technical details, and mitigation steps below.

Understanding CVE-2023-35133

This section provides an overview of the CVE-2023-35133 vulnerability affecting Moodle.

What is CVE-2023-35133?

CVE-2023-35133 is a vulnerability in Moodle versions 4.2, 4.1 to 4.1.3, 4.0 to 4.0.8, 3.11 to 3.11.14, 3.9 to 3.9.21 and earlier unsupported versions. The flaw arises from incorrectly checking 0.0.0.0 against cURL blocked hosts lists, leading to SSRF risk.

The Impact of CVE-2023-35133

The vulnerability poses a Server-Side Request Forgery (SSRF) risk, allowing attackers to send crafted requests from the server, potentially leading to unauthorized access to internal systems and data.

Technical Details of CVE-2023-35133

Explore the specific technical aspects of the CVE-2023-35133 vulnerability.

Vulnerability Description

The flaw in Moodle's logic allows an SSRF attack by not properly handling 0.0.0.0 against the cURL blocked hosts lists, opening a potential attack vector.

Affected Systems and Versions

Moodle versions 4.2, 4.1 to 4.1.3, 4.0 to 4.0.8, 3.11 to 3.11.14, 3.9 to 3.9.21, and earlier unsupported versions are impacted by this vulnerability.

Exploitation Mechanism

Attackers can exploit this vulnerability by manipulating the SSRF risk to send requests to internal systems that may be behind firewalls or not directly accessible.

Mitigation and Prevention

Discover the steps to mitigate and prevent exploitation of CVE-2023-35133 in Moodle.

Immediate Steps to Take

Update to the latest supported version of Moodle to patch the vulnerability and protect against SSRF attacks.
Implement network controls and filters to restrict outgoing network connections and monitor for SSRF attempts.

Long-Term Security Practices

Regularly monitor Moodle security advisories for updates and patches related to SSRF vulnerabilities.
Educate system administrators and users about the risks associated with SSRF and the importance of secure coding practices.

Patching and Updates

Stay informed about security patches and updates released by Moodle developers to address vulnerabilities, including SSRF risks.