CVE-2015-5342 in Moodle
Summary
by MITRE
The choice module 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 allows remote authenticated users to bypass intended access restrictions by visiting a URL to add or delete responses in the closed state.
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Analysis
by VulDB Data Team • 07/08/2022
The vulnerability identified as CVE-2015-5342 affects the choice module within Moodle learning management systems across multiple versions including 2.6.11, 2.7.11, 2.8.9, and 2.9.3. This security flaw represents a critical access control bypass that enables authenticated users to manipulate survey responses even when the choice activity has been closed. The issue stems from inadequate validation of user permissions during URL-based operations, specifically when attempting to add or delete responses in closed choice activities. This vulnerability directly impacts the integrity and confidentiality of survey data within educational institutions using Moodle platforms.
The technical implementation of this flaw resides in the choice module's insufficient authorization checks when processing HTTP requests for response modifications. When a user visits a specific URL to perform add or delete operations on choice responses, the system fails to properly verify whether the user has appropriate permissions to modify responses in a closed activity. This represents a classic authorization bypass vulnerability that aligns with CWE-285, which addresses improper authorization in software systems. The flaw occurs because the system does not adequately validate the current state of the choice activity or the user's role within the course context before executing the requested modification operations.
The operational impact of this vulnerability extends beyond simple data manipulation to potentially compromise the entire survey integrity within Moodle environments. An authenticated attacker with knowledge of the specific URL structure can exploit this weakness to alter survey responses even after the choice activity has been closed, potentially affecting grade calculations, statistical analysis, and the overall validity of collected data. This vulnerability particularly affects educational institutions where choice activities are used for student feedback, course selection, or voting mechanisms, as it allows unauthorized modifications that could skew results and undermine the trustworthiness of the collected information. The attack vector requires only a valid user account and knowledge of the target URL structure, making it accessible to both internal users and potentially external attackers who have gained legitimate access to the platform.
Organizations using affected Moodle versions should immediately apply the security patches released by Moodle developers to address this vulnerability. The recommended mitigation includes upgrading to Moodle versions 2.6.11, 2.7.11, 2.8.9, or 2.9.3, which contain the necessary code modifications to properly validate access permissions for choice module operations. Security administrators should also implement network monitoring to detect unusual URL access patterns that might indicate exploitation attempts, and conduct regular security audits of Moodle installations to ensure all patches are properly applied. Additionally, implementing role-based access controls and limiting user permissions to only necessary functions can help reduce the potential impact of similar vulnerabilities. This vulnerability demonstrates the importance of proper input validation and access control mechanisms in web applications, aligning with ATT&CK technique T1078 for valid accounts and T1566 for credential access through application vulnerabilities.