CVE-2016-3733 in Moodle
Summary
by MITRE
The "restore teacher" feature in Moodle 3.0 through 3.0.3, 2.9 through 2.9.5, 2.8 through 2.8.11, 2.7 through 2.7.13, and earlier allows remote authenticated users to overwrite the course idnumber.
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Analysis
by VulDB Data Team • 12/21/2020
The vulnerability described in CVE-2016-3733 affects the Moodle learning management system and specifically targets the "restore teacher" functionality across multiple versions including 3.0 through 3.0.3, 2.9 through 2.9.5, 2.8 through 2.8.11, 2.7 through 2.7.13, and earlier releases. This issue represents a significant security flaw that allows authenticated attackers to manipulate course identifiers within the system. The vulnerability stems from insufficient input validation and access control mechanisms within the course restoration process, which is typically used by educators to restore course content from backup files. When users with appropriate privileges attempt to restore courses, the system fails to properly validate or sanitize the idnumber parameter that is being overwritten during the restoration process.
The technical exploitation of this vulnerability occurs when authenticated users leverage the restore teacher feature to import course data while simultaneously modifying the idnumber field. This flaw enables attackers to overwrite existing course identifiers, potentially causing conflicts in course management and disrupting the integrity of the learning environment. The idnumber field serves as a unique identifier for courses within Moodle's database, and unauthorized modification can lead to data inconsistency issues, broken references, and potential information disclosure. The vulnerability is classified under CWE-20 as "Improper Input Validation" and aligns with ATT&CK technique T1078 which involves valid accounts and privileges being used to gain access to systems. This allows an attacker to perform unauthorized modifications without requiring elevated privileges beyond standard user authentication.
The operational impact of this vulnerability extends beyond simple data manipulation, as it can compromise the overall integrity and reliability of the Moodle platform. Course idnumbers are critical for maintaining consistent references across various system components including enrollment records, grade tracking, and administrative reporting. When these identifiers are overwritten, it can cause cascading failures in course management workflows and potentially expose sensitive educational data. The vulnerability particularly affects institutions that rely heavily on automated course management systems and integration with external learning analytics tools. Organizations may experience disruptions in their learning management processes, and the ability to track student progress and course completion could become compromised. The vulnerability also presents a risk for attackers seeking to manipulate course enrollment data or create confusion among users by altering course identifiers.
Mitigation strategies for CVE-2016-3733 should focus on immediate patch application to the affected Moodle versions, as well as implementing additional access controls and input validation measures. System administrators should ensure that all Moodle installations are updated to versions that contain the security fixes for this vulnerability, with the most recent stable releases recommended for deployment. Organizations should also implement network segmentation and monitoring to detect unusual activity patterns related to course restoration operations. The principle of least privilege should be enforced, limiting access to course restoration features only to authorized personnel with legitimate business requirements. Additionally, database audit logging should be enabled to track modifications to course idnumbers and other critical identifiers. Regular security assessments and vulnerability scanning should be conducted to identify similar issues within the Moodle platform and its associated components, as this vulnerability demonstrates the importance of proper input validation in educational technology systems.