CVE-2018-14630 in Moodle
Summary
by MITRE
moodle before versions 3.5.2, 3.4.5, 3.3.8, 3.1.14 is vulnerable to an XML import of ddwtos could lead to intentional remote code execution. When importing legacy 'drag and drop into text' (ddwtos) type quiz questions, it was possible to inject and execute PHP code from within the imported questions, either intentionally or by importing questions from an untrusted source.
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Analysis
by VulDB Data Team • 05/16/2023
The vulnerability identified as CVE-2018-14630 represents a critical remote code execution flaw within Moodle learning management systems prior to specific patch versions. This security weakness specifically affects Moodle installations running versions 3.5.2, 3.4.5, 3.3.8, and 3.1.14, creating a significant risk for educational institutions and organizations relying on the platform for online learning management. The vulnerability stems from insufficient input validation during the import process of legacy drag and drop into text quiz question types, which are commonly used in assessment creation within the Moodle environment.
The technical flaw manifests through the XML import mechanism that processes ddwtos (drag and drop into text) quiz questions. When Moodle imports these legacy question types, it fails to properly sanitize or validate the XML content, allowing malicious actors to inject PHP code directly into the question data. This occurs because the system does not adequately distinguish between legitimate question content and potentially malicious code embedded within the XML structure. The vulnerability is particularly dangerous as it can be exploited through legitimate import functionality, making it difficult to detect and prevent through standard security monitoring measures.
The operational impact of this vulnerability extends beyond simple data compromise, as it enables full remote code execution on affected Moodle servers. An attacker who gains access to import functionality or can convince a user to import malicious content can execute arbitrary PHP code with the privileges of the web server process. This creates a pathway for complete system compromise, data exfiltration, privilege escalation, and potential lateral movement within network environments where Moodle is deployed. The vulnerability is particularly concerning in educational settings where multiple users may have import privileges or where untrusted content sources are commonly encountered.
Organizations should immediately implement mitigations including updating to the patched versions of Moodle as specified in the CVE advisory, implementing strict access controls around import functionality, and conducting thorough security reviews of existing question libraries. The vulnerability aligns with CWE-94, which describes "Improper Control of Generation of Code ('Code Injection')" and maps to ATT&CK technique T1059.007 for "Command and Scripting Interpreter: PowerShell" within the execution phase. Security measures should include XML schema validation, input sanitization, and network-level monitoring to detect suspicious import activities, while also implementing principle of least privilege access controls for user accounts with import capabilities.
Additional defensive measures include regular security audits of imported content, implementation of automated vulnerability scanning tools, and establishing secure coding practices for XML processing within Moodle installations. The vulnerability demonstrates the critical importance of input validation in web applications and highlights how legacy import mechanisms can introduce security risks when not properly secured against code injection attacks. Organizations should also consider implementing web application firewalls and intrusion detection systems to monitor for exploitation attempts targeting this specific vulnerability.