CVE-2016-3731 in Moodle
Summary
by MITRE
Moodle 3.0 through 3.0.3, 2.9 through 2.9.5, and 2.8 through 2.8.11 allows remote attackers to obtain the names of hidden forums and forum discussions.
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Analysis
by VulDB Data Team • 12/21/2020
Moodle is a widely deployed open source learning management system that serves millions of educational institutions globally. The vulnerability described in CVE-2016-3731 represents a significant information disclosure flaw that affects multiple versions of the platform including 3.0 through 3.0.3, 2.9 through 2.9.5, and 2.8 through 2.8.11. This vulnerability falls under the category of information disclosure attacks where unauthorized remote attackers can access sensitive data that should remain hidden from users. The flaw specifically targets the forum functionality within Moodle where certain forum names and discussion titles are marked as hidden or restricted but can still be enumerated by malicious actors. This vulnerability is classified as CWE-200 Information Exposure and aligns with ATT&CK technique T1213 Data from Information Repositories which focuses on accessing data from repository systems.
The technical nature of this vulnerability stems from inadequate access control mechanisms within the forum module of Moodle. When administrators configure forums or discussions as hidden, they expect these elements to be completely inaccessible to unauthorized users. However, the flaw allows remote attackers to bypass these access restrictions through specific API calls or direct URL manipulation. The vulnerability essentially enables attackers to discover the existence of hidden forums and their associated discussions without proper authentication or authorization. This occurs due to improper validation of user permissions and insufficient input sanitization when processing forum-related requests. The flaw demonstrates a classic case of privilege escalation through information enumeration where unauthorized parties can gain knowledge of system structure and content that should remain private.
The operational impact of this vulnerability is substantial for educational institutions relying on Moodle for their learning management needs. Attackers who exploit this vulnerability can gain intelligence about the internal structure of course forums, identify sensitive discussions, and potentially map out the educational content landscape. This information can be used for further attacks including social engineering, targeted phishing campaigns, or identifying potential targets for more sophisticated exploitation. The exposure of hidden forum names and discussion titles may reveal confidential student information, instructor communications, or course materials that should remain private. Organizations using affected Moodle versions face increased risk of data breaches and privacy violations, particularly in environments where academic integrity and student privacy are paramount. The vulnerability also undermines the trust that users place in the system's access control mechanisms.
Mitigation strategies for CVE-2016-3731 require immediate action from affected organizations. The primary solution involves upgrading to patched versions of Moodle where the access control mechanisms have been properly implemented to prevent unauthorized enumeration of hidden forums. Organizations should also implement network-level firewalls and access controls to limit exposure to the Moodle application. Security monitoring should be enhanced to detect unusual patterns of forum access attempts and enumeration activities. Additionally, administrators should review and tighten forum access settings to minimize the exposure of sensitive content. Regular security audits and vulnerability assessments should be conducted to identify similar access control flaws. The remediation process should include comprehensive testing to ensure that the patch does not introduce regressions in functionality while properly addressing the information disclosure vulnerability. Organizations should also consider implementing web application firewalls and additional monitoring solutions to detect and prevent exploitation attempts.