CVE-2020-14320 in Moodle
Summary
by MITRE • 08/17/2022
In Moodle before 3.9.1, 3.8.4 and 3.7.7, the filter in the admin task log required extra sanitizing to prevent a reflected XSS risk.
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Analysis
by VulDB Data Team • 09/17/2022
The vulnerability identified as CVE-2020-14320 represents a reflected cross-site scripting flaw within the Moodle learning management system that affects versions prior to 3.9.1, 3.8.4, and 3.7.7. This security issue resides within the administrative task log filter functionality, which serves as a critical component for monitoring system operations and administrative activities. The flaw allows malicious actors to inject malicious scripts into the system through improperly sanitized input fields, potentially compromising the security of administrative interfaces and user sessions. The vulnerability specifically impacts the filter mechanism that processes user inputs for logging administrative tasks, creating an attack surface where reflected XSS can occur when administrators view filtered log entries.
The technical implementation of this vulnerability stems from insufficient input sanitization within the administrative task log processing pipeline. When administrators interact with the filter functionality to search or sort through administrative logs, the system fails to properly sanitize user-provided input parameters before rendering them in the web interface. This oversight creates a classic reflected XSS scenario where malicious payloads embedded in filter parameters are executed in the context of the victim's browser session. The vulnerability is particularly concerning because it targets administrative interfaces where users possess elevated privileges, potentially allowing attackers to escalate their privileges or gain unauthorized access to sensitive system functions. This flaw aligns with CWE-79, which specifically addresses cross-site scripting vulnerabilities, and demonstrates how insufficient input validation can create persistent security risks in web applications.
The operational impact of this vulnerability extends beyond simple script execution, as it provides attackers with potential access to administrative controls and sensitive system information. When administrators view filtered log entries containing malicious payloads, the injected scripts execute within their browser context, potentially leading to session hijacking, data exfiltration, or further privilege escalation attacks. The reflected nature of this XSS means that attackers must lure administrators into clicking malicious links or navigating to specifically crafted URLs containing the exploit payload, making it particularly dangerous in targeted attack scenarios. This vulnerability affects the core integrity of Moodle's administrative security model and could enable attackers to compromise the entire learning management system if successful exploitation occurs. The impact is further amplified by the fact that administrative interfaces typically contain sensitive information and control mechanisms that could be leveraged for broader system compromise.
Organizations using affected Moodle versions should implement immediate mitigations including upgrading to the patched versions 3.9.1, 3.8.4, or 3.7.7, which contain proper input sanitization measures for the administrative task log filter. Additional protective measures include implementing content security policies that restrict script execution in administrative interfaces, monitoring for suspicious filter parameter usage, and conducting regular security audits of administrative components. Security teams should also consider implementing web application firewalls to detect and block suspicious input patterns targeting administrative interfaces. The vulnerability demonstrates the critical importance of input validation in security-critical components and aligns with ATT&CK technique T1059.001 for command and scripting interpreter, as reflected XSS attacks can be used to execute malicious code in victim browsers. Organizations should also review their incident response procedures to ensure rapid detection and remediation of similar vulnerabilities in other system components that handle administrative input processing.