CVE-2012-3398 in Moodle
Summary
by MITRE
Algorithmic complexity vulnerability in Moodle 1.9.x before 1.9.19, 2.0.x before 2.0.10, 2.1.x before 2.1.7, and 2.2.x before 2.2.4 allows remote authenticated users to cause a denial of service (CPU consumption) by using the advanced-search feature on a database activity that has many records.
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Analysis
by VulDB Data Team • 12/07/2021
The CVE-2012-3398 vulnerability represents a critical algorithmic complexity issue within the Moodle learning management system that affects multiple version branches including 1.9.x through 1.9.18, 2.0.x through 2.0.9, 2.1.x through 2.1.6, and 2.2.x through 2.2.3. This vulnerability resides in the advanced-search functionality of database activities within Moodle, creating a significant security risk that can be exploited by authenticated remote attackers to execute denial of service attacks. The flaw specifically targets the computational complexity of search operations when dealing with database activities containing large numbers of records, making it particularly dangerous in environments where extensive database content is common. The vulnerability aligns with CWE-400 which categorizes issues related to algorithmic complexity and resource consumption problems that can lead to denial of service conditions.
The technical implementation of this vulnerability stems from how Moodle processes search queries within database activities that contain substantial data sets. When an authenticated user accesses the advanced-search feature on a database activity with many records, the system's search algorithm exhibits exponential or polynomial time complexity behavior that scales poorly with increasing data volume. This inefficient processing causes the server to consume excessive cpu resources during search operations, leading to significant performance degradation or complete system unresponsiveness. The attack vector requires only authentication to the Moodle system, making it accessible to any legitimate user with appropriate privileges. The computational inefficiency manifests in the search algorithm's handling of large datasets where it performs redundant or overly complex operations that could be optimized to maintain linear or logarithmic complexity rather than the problematic higher-order complexity.
The operational impact of this vulnerability extends beyond simple performance degradation to potentially compromise entire Moodle deployments and educational services. Organizations relying on Moodle for online learning may experience complete service interruption when attackers exploit this vulnerability, particularly during peak usage times when database activities contain thousands or millions of records. The resource exhaustion affects not only the specific search functionality but can also impact overall system performance, potentially causing cascading failures that affect other services running on the same infrastructure. This vulnerability particularly impacts educational institutions and training organizations where database activities often contain extensive content such as student records, course materials, or assessment data that grows over time. The vulnerability's exploitation can occur during routine administrative tasks or user searches, making it difficult to predict and prevent.
Mitigation strategies for CVE-2012-3398 should prioritize immediate patching of affected Moodle installations to versions 1.9.19, 2.0.10, 2.1.7, and 2.2.4 respectively, which contain the necessary code modifications to address the algorithmic complexity issue. System administrators should implement monitoring solutions to detect unusual cpu consumption patterns that may indicate exploitation attempts, particularly around database search operations. Access controls and user privilege management should be reviewed to limit access to advanced-search features where possible, reducing the attack surface. The vulnerability's characteristics align with ATT&CK technique T1499 which covers resource exhaustion attacks, making it important for security teams to consider this threat when implementing defensive measures. Organizations should also implement rate limiting on search operations and consider implementing caching mechanisms for frequently accessed database content to reduce the computational burden on search operations. Regular security assessments and vulnerability scanning should include verification of Moodle installations to ensure all patches have been properly applied and that the system maintains its intended performance characteristics.