CVE-2014-7834 in Moodle
Summary
by MITRE
mod/forum/externallib.php in Moodle 2.6.x before 2.6.6 and 2.7.x before 2.7.3 does not verify group permissions, which allows remote authenticated users to access a forum via the forum_get_discussions web service.
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Analysis
by VulDB Data Team • 04/04/2022
The vulnerability identified as CVE-2014-7834 resides within the Moodle learning management system's external library implementation, specifically in the mod/forum/externallib.php file. This issue affects Moodle versions 2.6.x prior to 2.6.6 and 2.7.x prior to 2.7.3, representing a critical security flaw that undermines the platform's access control mechanisms. The vulnerability stems from insufficient validation of group permissions within the forum_get_discussions web service, creating a pathway for unauthorized information disclosure.
The technical flaw manifests as a missing authorization check that should validate whether authenticated users belong to the appropriate groups before granting access to forum discussions. When users invoke the forum_get_discussions web service endpoint, the system fails to verify that the requesting user has proper group membership or permission levels required to view specific forum content. This represents a classic access control vulnerability that aligns with CWE-284, which categorizes improper access control issues in software systems. The flaw allows malicious actors to bypass normal group-based restrictions and retrieve forum discussions that should be restricted to specific user cohorts.
The operational impact of this vulnerability extends beyond simple information disclosure, as it enables authenticated attackers to access potentially sensitive educational content that may contain personal student information, assignment details, or discussion threads between instructors and students. This represents a significant risk in educational environments where data privacy and academic integrity are paramount. Attackers can leverage this vulnerability to gain unauthorized access to forum discussions that are typically restricted to specific groups such as course participants, cohort members, or specific user roles. The implications are particularly severe in environments where Moodle is used for confidential academic discussions, peer review processes, or course-specific communications.
From a threat modeling perspective, this vulnerability maps to multiple ATT&CK techniques including T1078 for valid accounts and T1566 for credential harvesting, as attackers can exploit legitimate authenticated sessions to access restricted content. The vulnerability also demonstrates poor principle of least privilege implementation, where the web service does not properly enforce the security boundaries that should exist between different user groups within the same course. Organizations using affected Moodle versions should immediately implement mitigations including updating to patched versions, reviewing and tightening group permission settings, and monitoring for unauthorized access attempts. Additionally, security administrators should consider implementing network-level controls to restrict access to web service endpoints and conduct thorough audits of forum access controls to ensure proper segregation of educational content across different user groups and course sections.