CVE-2015-5339 in Moodle
Summary
by MITRE
The core_enrol_get_enrolled_users web service in enrol/externallib.php in Moodle through 2.6.11, 2.7.x before 2.7.11, 2.8.x before 2.8.9, and 2.9.x before 2.9.3 does not properly implement group-based access restrictions, which allows remote authenticated users to obtain sensitive course-participant information via a web-service request.
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Analysis
by VulDB Data Team • 07/08/2022
The vulnerability identified as CVE-2015-5339 represents a critical access control flaw within the Moodle learning management system that affects multiple version branches including 2.6.11, 2.7.11, 2.8.9, and 2.9.3. This issue resides in the core_enrol_get_enrolled_users web service implementation within the enrol/externallib.php file, where the system fails to properly enforce group-based access restrictions that are fundamental to maintaining user privacy and data segregation within educational environments. The flaw allows authenticated attackers to bypass intended access controls and retrieve sensitive information about course participants that should otherwise be restricted based on group membership or role-based permissions.
The technical implementation of this vulnerability stems from inadequate validation of group membership constraints within the external web service interface. When users make authenticated requests to the enrol_get_enrolled_users endpoint, the system does not properly verify whether the requesting user has appropriate permissions to view all enrolled participants or if they should be restricted to specific group members only. This represents a clear violation of the principle of least privilege and demonstrates a failure in the authorization mechanism that should prevent unauthorized data exposure. The vulnerability is categorized under CWE-284 which specifically addresses inadequate access control or improper privileges, and aligns with ATT&CK technique T1078 which covers valid accounts and legitimate credentials for unauthorized access.
The operational impact of this vulnerability extends beyond simple data exposure to potentially compromise the integrity of educational data management systems. Attackers can exploit this flaw to gather comprehensive information about course participants including enrollment status, user roles, and potentially personal details that should remain private within group-based learning environments. This capability undermines the trust model that educational institutions rely upon when implementing online learning platforms and could enable further attacks such as social engineering, credential harvesting, or targeted phishing campaigns. The vulnerability affects the confidentiality aspect of the CIA triad and represents a significant risk to privacy-sensitive educational data.
Organizations utilizing affected Moodle versions should immediately implement mitigation strategies including applying the available security patches, reviewing and strengthening group-based access control configurations, and monitoring for unauthorized access attempts to enrollment data. Administrators should also consider implementing additional network-level controls and web application firewalls to detect and prevent exploitation attempts. The remediation process should involve comprehensive testing of access controls to ensure that group-based restrictions function properly and that no unauthorized data exposure occurs. This vulnerability highlights the importance of regular security assessments and patch management in educational technology environments where user privacy and data protection are paramount concerns.