CVE-2016-2152 in Moodle
Summary
by MITRE
Multiple cross-site scripting (XSS) vulnerabilities in auth/db/auth.php in Moodle through 2.6.11, 2.7.x before 2.7.13, 2.8.x before 2.8.11, 2.9.x before 2.9.5, and 3.0.x before 3.0.3 allow remote attackers to inject arbitrary web script or HTML via an external DB profile field.
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Analysis
by VulDB Data Team • 08/21/2022
The vulnerability identified as CVE-2016-2152 represents a critical cross-site scripting flaw affecting multiple versions of the Moodle learning management system. This vulnerability resides within the auth/db/auth.php file, which handles authentication processes when Moodle integrates with external database systems. The flaw specifically impacts Moodle versions through 2.6.11, 2.7.x before 2.7.13, 2.8.x before 2.8.11, 2.9.x before 2.9.5, and 3.0.x before 3.0.3, making it a widespread issue affecting the entire Moodle ecosystem during that period. The vulnerability allows remote attackers to inject malicious web scripts or HTML code through external database profile fields, creating a significant security risk for educational institutions relying on Moodle for their learning platforms.
The technical nature of this vulnerability stems from insufficient input validation and output sanitization within the database authentication module. When Moodle processes user authentication against external databases, it retrieves user profile information including custom profile fields that are stored in external database systems. The flaw occurs because the application fails to properly sanitize or escape data retrieved from these external sources before displaying it within the web interface. This lack of proper data sanitization creates an XSS attack vector where malicious actors can craft profile field data containing script tags or other malicious HTML content that executes in the context of other users' browsers when their profiles are displayed.
The operational impact of this vulnerability extends beyond simple script injection, as it can enable attackers to perform various malicious activities within the Moodle environment. An attacker who successfully exploits this vulnerability could steal session cookies, redirect users to malicious websites, deface course content, or even escalate privileges within the system. The vulnerability is particularly dangerous in educational environments where Moodle platforms often contain sensitive student information, course materials, and personal data. The attack surface is broad since any external database integration that uses profile fields could be exploited, making this vulnerability particularly concerning for institutions that rely on external authentication systems or database integrations for user management.
This vulnerability maps directly to CWE-79, which specifically addresses cross-site scripting flaws in software applications. The weakness occurs in the data handling process where external database profile fields are not properly validated or escaped before being rendered in web pages. From an ATT&CK framework perspective, this vulnerability aligns with T1059.005 for command and scripting interpreter, specifically web shell execution through XSS, and T1566 for phishing attacks that could leverage this vulnerability to deliver malicious payloads. The attack requires minimal privileges and can be executed remotely, making it particularly attractive to threat actors targeting educational institutions. Organizations should implement immediate mitigations including updating to patched versions of Moodle, implementing proper input validation for external database fields, and monitoring for suspicious profile field data that might indicate exploitation attempts.
The remediation strategy for this vulnerability centers on applying the official security patches released by Moodle developers for the affected versions. System administrators should prioritize updating their Moodle installations to versions 2.7.13, 2.8.11, 2.9.5, or 3.0.3 respectively, which contain the necessary fixes for the XSS vulnerability. Additionally, organizations should implement enhanced input validation mechanisms for external database integration points and consider implementing content security policies to mitigate potential exploitation even if other mitigations fail. Regular security audits of database integration points and profile field configurations should be conducted to identify and remediate similar vulnerabilities in other parts of the system. The vulnerability highlights the importance of proper data sanitization in web applications and demonstrates how seemingly minor input validation gaps can create significant security risks in educational platforms handling sensitive user data.