CVE-2023-5539 in Moodle
Summary
by MITRE • 11/09/2023
A remote code execution risk was identified in the Lesson activity. By default this was only available to teachers and managers.
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Analysis
by VulDB Data Team • 11/11/2023
The vulnerability CVE-2023-5539 represents a critical remote code execution flaw within the Lesson activity component of a learning management system. This vulnerability exists in the way the system processes user inputs and handles file operations within the lesson module functionality. The flaw allows unauthorized users to execute arbitrary code on the target system remotely, potentially leading to complete system compromise. The vulnerability is particularly concerning because it affects a core educational module that is widely deployed across various institutions and organizations using the platform.
The technical implementation of this vulnerability stems from inadequate input validation and sanitization mechanisms within the Lesson activity processing pipeline. When users interact with lesson content, particularly through file upload or content manipulation features, the system fails to properly validate and sanitize user-supplied data before processing. This creates an exploitation vector where malicious actors can inject malicious code that gets executed with the privileges of the web application. The vulnerability is classified under CWE-94, which specifically addresses "Improper Control of Generation of Code" and falls within the broader category of code injection flaws that have been consistently identified as high-risk security concerns in the OWASP Top Ten.
The operational impact of CVE-2023-5539 extends beyond simple data compromise, as the vulnerability allows for complete system takeover. Even though the default configuration restricts access to teachers and managers, the vulnerability could be exploited by attackers who gain access to these privileged accounts through credential theft, social engineering, or other attack vectors. The remote execution capability means that attackers can perform actions such as creating new user accounts, modifying existing content, accessing sensitive student data, and potentially establishing persistent backdoors. This aligns with ATT&CK technique T1059 which covers command and script injection, and T1078 which covers valid accounts for maintaining access.
Mitigation strategies for this vulnerability require immediate patching of the affected system components, as the primary fix involves implementing proper input validation and sanitization controls. Organizations should also implement network segmentation to limit access to the lesson module, enforce strict access controls and audit logging for all lesson-related activities, and conduct thorough security assessments of all user accounts with access to educational modules. Additionally, implementing web application firewalls and intrusion detection systems can help detect and prevent exploitation attempts. The vulnerability demonstrates the importance of securing educational technology platforms, as these systems often contain sensitive student information and represent attractive targets for cyber adversaries. Regular security assessments and vulnerability management programs should include thorough testing of all educational modules to prevent similar issues from occurring in the future, particularly focusing on input validation and privilege management controls.