CVE-2012-3390 in Moodle
Summary
by MITRE
lib/filelib.php in Moodle 2.1.x before 2.1.7 and 2.2.x before 2.2.4 does not properly restrict file access after a block has been hidden, which allows remote authenticated users to obtain sensitive information by reading a file that is embedded in a block.
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Analysis
by VulDB Data Team • 12/06/2021
The vulnerability described in CVE-2012-3390 affects Moodle learning management systems version 2.1.x before 2.1.7 and 2.2.x before 2.2.4, representing a significant access control flaw that undermines the platform's security model. This issue stems from improper file access restrictions within the lib/filelib.php component, specifically when blocks are hidden from users. The flaw exists in the core file handling mechanisms that govern how Moodle manages file permissions and visibility within its user interface.
The technical implementation of this vulnerability resides in the filelib.php module which handles file operations and access controls within Moodle's block system. When a block is hidden from users, the system fails to properly enforce access restrictions on files that are embedded within those blocks. This creates a scenario where authenticated users can bypass normal access controls and retrieve sensitive files that should only be accessible to authorized personnel. The vulnerability manifests when users attempt to read files that are embedded within blocks, exploiting the incomplete access control checks that occur after block hiding operations.
From an operational perspective, this vulnerability allows remote authenticated users to obtain sensitive information that could include personal data, course materials, system configurations, or other confidential content. The impact extends beyond simple information disclosure as it represents a privilege escalation vector that could enable attackers to gain unauthorized access to resources they should not be able to access. This flaw particularly affects educational institutions that rely on Moodle for course management, as it could expose student records, assessment materials, or administrative documents through seemingly innocuous block content.
The vulnerability aligns with CWE-284, which addresses improper access control issues in software systems, and demonstrates how inadequate access control implementation can create security gaps in content management platforms. From an attack framework perspective, this vulnerability maps to ATT&CK technique T1078 for valid accounts and T1566 for credential access, as it leverages legitimate user authentication to bypass access controls. The flaw essentially creates a backdoor mechanism where hidden blocks continue to expose their embedded file content to authenticated users who should not have access to such materials.
Organizations using affected Moodle versions should implement immediate mitigations including upgrading to patched versions 2.1.7 and 2.2.4, which contain the necessary access control fixes. Additional protective measures include reviewing block configurations to minimize embedded file usage, implementing stricter access controls for sensitive content, and monitoring user access logs for unusual file access patterns. Security teams should also consider implementing network-level controls to restrict access to file operations and ensure that file access controls are properly enforced throughout the system architecture. The vulnerability underscores the importance of proper access control implementation in web-based learning platforms where multiple user roles and permission levels must be carefully managed to prevent unauthorized information disclosure.