CVE-2019-3808 in Moodle
Summary
by MITRE
A flaw was found in Moodle versions 3.6 to 3.6.1, 3.5 to 3.5.3, 3.4 to 3.4.6, 3.1 to 3.1.15 and earlier unsupported versions. The 'manage groups' capability did not have the 'XSS risk' flag assigned to it, but does have that access in certain places. Note that the capability is intended for use by trusted users, and is only assigned to teachers and managers by default.
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Analysis
by VulDB Data Team • 08/07/2023
This vulnerability exists in Moodle learning management systems across multiple versions including 3.6.0-3.6.1, 3.5.0-3.5.3, 3.4.0-3.4.6, and 3.1.0-3.1.15, along with unsupported earlier releases. The flaw stems from an improper security configuration where the 'manage groups' capability lacks the appropriate 'XSS risk' flag in the system's security framework. This misconfiguration creates a scenario where users with the 'manage groups' permission can potentially execute cross-site scripting attacks in specific contexts despite not being explicitly flagged as high-risk operations. The vulnerability is particularly concerning because it operates under the assumption that users with this capability are trusted individuals, yet the system fails to properly restrict their access in potentially dangerous situations. The capability is by default assigned to teachers and managers within the Moodle environment, making it accessible to users who may not fully understand the security implications of their actions.
The technical implementation of this vulnerability occurs when the 'manage groups' capability is used in contexts where user input is processed without adequate sanitization or validation. This flaw allows for the execution of malicious scripts when users with appropriate permissions create or modify group information that gets rendered on web pages without proper security measures. The XSS risk is not properly acknowledged or mitigated for this specific capability, creating a potential attack vector where malicious actors could leverage their legitimate access to inject harmful scripts into group management interfaces. This represents a classic case of insufficient security controls where the system's permission model does not adequately account for the potential for cross-site scripting exploitation within certain functional areas.
The operational impact of this vulnerability extends beyond simple data integrity concerns to potentially compromise the entire Moodle platform. Attackers who can manipulate group information through the 'manage groups' capability could execute scripts that steal session cookies, redirect users to malicious sites, or even modify group memberships to gain unauthorized access to other users' data. The risk is particularly elevated because the capability is assigned to teachers and managers who typically have legitimate access to sensitive educational information. This vulnerability could enable unauthorized data access, session hijacking, and potentially full system compromise if attackers can leverage the XSS to escalate privileges or gain deeper access to the platform's core functionality. The attack surface expands when considering that group management interfaces often contain rich text editors or other input fields that may not properly sanitize user-supplied content.
Mitigation strategies for this vulnerability should focus on implementing proper security flagging for the 'manage groups' capability, ensuring that all operations within this scope are properly validated and sanitized against XSS attacks. System administrators should immediately update to patched versions of Moodle where the security flagging has been corrected and proper input sanitization has been implemented. The remediation process should include reviewing and adjusting capability assignments to ensure that only users who require the full scope of group management permissions are granted access, while also implementing additional input validation and output encoding measures. Organizations should also consider implementing web application firewalls and additional monitoring to detect potential exploitation attempts, while following the CWE guidelines for proper input validation and output encoding to prevent cross-site scripting vulnerabilities. This vulnerability demonstrates the importance of comprehensive security auditing and proper capability assignment within educational platforms to prevent unauthorized access and data compromise.