CVE-2021-24182 in Tutor LMS Plugin
Summary
by MITRE • 04/06/2021
The tutor_quiz_builder_get_answers_by_question AJAX action from the Tutor LMS – eLearning and online course solution WordPress plugin before 1.8.3 was vulnerable to UNION based SQL injection that could be exploited by students.
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Analysis
by VulDB Data Team • 04/10/2021
The vulnerability identified as CVE-2021-24182 affects the Tutor LMS WordPress plugin, specifically targeting the tutor_quiz_builder_get_answers_by_question AJAX action. This security flaw exists in versions prior to 1.8.3 and represents a critical SQL injection vulnerability that undermines the integrity of the plugin's quiz functionality. The vulnerability is particularly concerning because it allows unauthenticated attackers with student-level privileges to execute malicious SQL queries against the underlying database, potentially compromising the entire learning management system infrastructure.
The technical implementation of this vulnerability stems from inadequate input validation and sanitization within the AJAX handler responsible for retrieving quiz answers. When a student accesses the quiz builder functionality, the plugin fails to properly escape or filter user-supplied parameters before incorporating them into SQL queries. This oversight creates an opportunity for attackers to inject malicious SQL code through the question ID parameter, enabling them to perform UNION-based SQL injection attacks. The vulnerability maps directly to CWE-89, which categorizes improper neutralization of special elements used in SQL commands, and aligns with ATT&CK technique T1071.004 for application layer protocol tunneling through SQL injection.
The operational impact of this vulnerability extends beyond simple data theft, as it provides attackers with the capability to extract sensitive information from the database including user credentials, course materials, and personal student data. Students who gain access to this vulnerability can potentially escalate their privileges or access restricted content, undermining the security model of the eLearning platform. The implications are particularly severe in educational environments where sensitive academic data and personal information are stored within the LMS system. Attackers could exploit this vulnerability to manipulate quiz results, access confidential course content, or even establish persistent access to the platform through credential theft.
Mitigation strategies should begin with immediate implementation of the patch released in version 1.8.3, which addresses the input sanitization issues within the AJAX handler. System administrators should also implement additional security measures including web application firewall rules to monitor and block suspicious SQL injection patterns, database query logging to detect anomalous activity, and regular security audits of plugin components. The vulnerability highlights the importance of validating all user inputs, especially in AJAX endpoints where privilege levels may be lower than expected. Organizations should also consider implementing principle of least privilege access controls, ensuring that even authenticated users cannot perform unauthorized database operations. Regular security assessments of WordPress plugins and themes remain essential to identify similar vulnerabilities that could compromise the integrity of online learning environments.