CVE-2019-3849 in Moodle
Summary
by MITRE
A vulnerability was found in moodle before versions 3.6.3, 3.5.5 and 3.4.8. Users could assign themselves an escalated role within courses or content accessed via LTI, by modifying the request to the LTI publisher site.
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Analysis
by VulDB Data Team • 08/08/2023
This vulnerability resides in the Moodle learning management system and represents a critical authorization flaw that allowed attackers to escalate their privileges within course environments. The issue specifically affected Moodle versions prior to 3.6.3, 3.5.5, and 3.4.8, indicating a widespread impact across multiple release branches. The vulnerability stems from insufficient input validation and improper access control mechanisms within the LTI (Learning Tools Interoperability) publisher functionality, which is designed to enable integration with external learning tools and content providers.
The technical flaw manifests when users manipulate requests sent to LTI publisher sites, allowing them to assign themselves elevated roles within courses or content. This occurs due to inadequate verification of role assignments and insufficient sanitization of parameters passed through LTI requests. Attackers could exploit this by modifying the LTI launch parameters to include unauthorized role assignments, effectively bypassing the normal role management controls that should restrict user permissions. The vulnerability operates at the intersection of trust boundaries between Moodle and external LTI tools, where the system fails to properly validate that the requested roles are legitimate and authorized for the requesting user.
The operational impact of this vulnerability is severe as it enables privilege escalation attacks that could allow malicious users to gain administrative or instructor-level access to course materials and student data. An attacker with basic user access could potentially elevate their privileges to course manager or administrator level, thereby gaining access to sensitive information, modifying course content, managing user enrollments, and potentially accessing other users' personal data. This represents a direct violation of the principle of least privilege and could lead to data breaches, unauthorized modifications, and complete compromise of course environments. The vulnerability is particularly concerning in educational institutions where Moodle systems contain sensitive student information and academic records.
Mitigation strategies should focus on immediate patching of affected Moodle versions to the recommended secure releases, which contain proper input validation and role assignment controls. Organizations should also implement additional monitoring of LTI-related activities and request parameters to detect anomalous behavior. The vulnerability aligns with CWE-285 (Improper Authorization) and represents a specific instance of improper access control that could be addressed through proper parameter validation and role management controls. From an ATT&CK framework perspective, this vulnerability maps to privilege escalation techniques and could be leveraged as part of broader attack chains targeting educational environments. Organizations should also consider implementing network segmentation and access controls around LTI integration points, along with regular security assessments of external tool integrations to prevent similar issues in other systems.