CVE-2012-2355 in Moodle
Summary
by MITRE
Moodle 2.1.x before 2.1.6 and 2.2.x before 2.2.3 allows remote authenticated users to bypass question:use* capability requirements and add arbitrary questions to a quiz via the questions feature.
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Analysis
by VulDB Data Team • 12/06/2021
The vulnerability described in CVE-2012-2355 represents a critical access control flaw within the Moodle learning management system that affects versions prior to 2.1.6 and 2.2.3. This issue stems from insufficient authorization checks within the quiz question management functionality, allowing authenticated users to exploit a capability bypass mechanism. The flaw specifically targets the question:use* capability requirements that are designed to control who can add questions to quizzes within the system. When exploited, this vulnerability enables malicious actors to circumvent the intended permission model and inject arbitrary questions into quizzes without proper authorization. The vulnerability is particularly concerning because it operates at the capability level within Moodle's robust access control system, which is fundamental to maintaining data integrity and user role-based access restrictions. The affected versions demonstrate a failure in implementing proper capability validation during the question addition process, creating a persistent security weakness that could be exploited by users with minimal privileges.
The technical implementation of this vulnerability involves a flaw in the question management code path where the system fails to properly verify whether the authenticated user possesses the necessary permissions to add specific types of questions to a quiz. This capability bypass occurs during the processing of question addition requests, where the system incorrectly grants access to question creation functionality regardless of the user's actual role permissions. The vulnerability can be classified under CWE-284, which addresses improper access control, specifically within the context of capability-based access control systems. From an operational standpoint, this flaw allows attackers to manipulate quiz content in ways that could compromise educational integrity, potentially enabling the injection of inappropriate questions, the creation of misleading assessments, or the execution of other malicious activities within the quiz environment. The attack vector requires only authenticated access to the system, making it particularly dangerous as it can be exploited by users who have legitimate access but should not have the privilege to modify quiz content.
The impact of this vulnerability extends beyond simple unauthorized access, as it fundamentally undermines the trust model that Moodle relies upon for maintaining secure educational environments. When users can bypass question:use* capability requirements, they gain the ability to modify assessment content in ways that could compromise the validity and integrity of educational evaluations. This capability bypass affects the core functionality of quiz management and could potentially be leveraged to create false assessments, introduce questions containing malicious content, or manipulate grading systems. The vulnerability demonstrates a critical gap in the access control implementation where the system fails to properly validate user permissions against the specific capabilities required for question manipulation. Security practitioners should note that this flaw aligns with ATT&CK technique T1078 which covers valid accounts and privilege escalation, as it allows unauthorized privilege exploitation through legitimate system access. Organizations using affected Moodle versions face significant risks including assessment integrity violations, potential data manipulation, and compromised educational content management. The vulnerability's exploitation requires minimal technical skill and can be performed by users who have basic access to the system, making it particularly dangerous in educational environments where multiple user roles and access levels are common.
Mitigation strategies for CVE-2012-2355 should focus on immediate patch application to the affected Moodle versions, ensuring that all systems are updated to versions 2.1.6 or later for 2.1.x releases and 2.2.3 or later for 2.2.x releases. Organizations should also implement additional monitoring of quiz management activities and review user capabilities to ensure that only authorized personnel have access to question addition functionality. Security teams should conduct comprehensive access control reviews and validate that capability requirements are properly enforced throughout the system. The vulnerability highlights the importance of proper input validation and capability checking in web applications, particularly those handling educational content and assessment data. Organizations should also consider implementing network segmentation and access controls to limit the scope of potential exploitation, while maintaining audit logs of all quiz-related activities for security monitoring purposes. Regular security assessments of LMS platforms are essential to identify and remediate similar capability bypass vulnerabilities that could compromise educational integrity and system security.