CVE-2011-4133 in Moodle
Summary
by MITRE
Cross-site request forgery (CSRF) vulnerability in Moodle 1.9.x before 1.9.11 allows remote attackers to hijack the authentication of unspecified victims for requests that modify an RSS feed in an RSS block.
Be aware that VulDB is the high quality source for vulnerability data.
Analysis
by VulDB Data Team • 12/06/2021
The CVE-2011-4133 vulnerability represents a critical cross-site request forgery flaw discovered in Moodle learning management systems version 1.9.x prior to 1.9.11. This vulnerability resides within the RSS block functionality of the platform, where attackers can exploit the lack of proper CSRF protection mechanisms to manipulate user sessions and execute unauthorized actions. The flaw specifically targets the RSS feed modification capabilities within Moodle's block system, creating a significant security risk for educational institutions relying on this software. The vulnerability operates by tricking authenticated users into executing unintended actions through maliciously crafted requests that appear legitimate to the server.
The technical implementation of this CSRF vulnerability stems from the absence of anti-CSRF tokens or similar validation mechanisms within the RSS block modification endpoints. When a user accesses a Moodle page containing an RSS block, the system should verify that requests modifying RSS feed configurations originate from legitimate user interactions rather than forged requests from external domains. The vulnerability allows attackers to construct malicious web pages or emails that, when visited by authenticated Moodle users, automatically submit requests to modify RSS feeds without proper authorization. This occurs because the application fails to validate the referer header or implement unique tokens that would distinguish between genuine user actions and maliciously crafted requests.
The operational impact of this vulnerability extends beyond simple data modification, as it enables attackers to potentially gain unauthorized control over user accounts and manipulate educational content. An attacker could modify RSS feeds to redirect users to malicious websites, inject harmful content into learning materials, or even alter feed configurations to disrupt the learning environment. The unspecified nature of victim targets suggests this vulnerability affects any authenticated user within the Moodle system, making it particularly dangerous in educational environments where multiple users access the platform simultaneously. The attack vector typically involves social engineering techniques where users are tricked into visiting malicious websites that contain hidden iframe elements or automated form submissions.
Organizations using Moodle version 1.9.x should prioritize immediate remediation through the installation of the 1.9.11 patch or subsequent updates to address this vulnerability. The fix typically involves implementing proper CSRF token validation mechanisms within the RSS block modification functionality, ensuring that all requests modifying user data include unique, unpredictable tokens that cannot be forged by attackers. Security administrators should also consider implementing additional monitoring of RSS feed modifications and user session activities to detect potential exploitation attempts. This vulnerability aligns with CWE-352, which specifically addresses Cross-Site Request Forgery weaknesses, and maps to ATT&CK technique T1566.001 for initial access through spearphishing attachments or links, demonstrating how such vulnerabilities can serve as entry points for broader attacks. The remediation process should include comprehensive testing to ensure that the CSRF protection mechanisms do not break legitimate functionality while providing adequate security against unauthorized modifications.