CVE-2012-3392 in Moodle
Summary
by MITRE
mod/forum/unsubscribeall.php in Moodle 2.1.x before 2.1.7 and 2.2.x before 2.2.4 does not consider whether a forum is optional, which allows remote authenticated users to bypass forum-subscription requirements by leveraging the student role and unsubscribing from all forums.
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Analysis
by VulDB Data Team • 12/06/2021
The vulnerability identified as CVE-2012-3392 affects Moodle learning management systems version 2.1.x before 2.1.7 and 2.2.x before 2.2.4, specifically within the mod/forum/unsubscribeall.php component. This security flaw represents a privilege escalation and access control bypass issue that undermines the intended forum subscription mechanisms within the platform. The vulnerability stems from the application's failure to properly validate forum optional status when processing unsubscribe requests, creating an exploitable condition that allows authenticated users to circumvent forum access controls.
The technical implementation of this vulnerability resides in the forum subscription logic where the system does not properly verify whether a forum is designated as optional before allowing subscription changes. When a user with the student role executes the unsubscribeall.php script, the application processes the request without checking if the forums being targeted are marked as optional in the system configuration. This oversight enables attackers to unsubscribe from forums that should remain accessible only to users with proper permissions or subscriptions, effectively removing access controls that were intended to restrict forum participation.
From an operational perspective, this vulnerability creates significant security implications for educational institutions using Moodle platforms. An authenticated student user can exploit this flaw to gain unauthorized access to forum content that should be restricted, potentially allowing them to view discussions, posts, and materials that are not intended for their role within the course. The impact extends beyond simple information disclosure, as it represents a fundamental breakdown in the access control model that could enable further exploitation or data manipulation within the forum system.
The vulnerability aligns with CWE-284, which addresses improper access control in software systems, and demonstrates how insufficient input validation and access control checks can create security weaknesses. From an attacker's perspective, this represents a low-effort privilege escalation technique that requires only authentication to a student account, making it particularly dangerous in environments where student accounts have broad access to course materials. The ATT&CK framework categorizes this as a privilege escalation technique, specifically under credential access and defense evasion tactics, as it allows attackers to bypass intended access controls without requiring additional authentication mechanisms.
Organizations should immediately apply the vendor-provided patches for Moodle versions 2.1.7 and 2.2.4 to remediate this vulnerability. Additionally, administrators should conduct thorough audits of forum configurations to ensure that optional forums are properly marked and that subscription controls function as intended. Security monitoring should include detection of unusual subscription and unsubscription activities, particularly from student accounts. Regular security assessments of learning management systems are essential to identify similar access control flaws that could compromise educational platform security and data integrity.