CVE-2015-3274 in Moodle
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in the user_get_user_details function in user/lib.php in Moodle through 2.6.11, 2.7.x before 2.7.9, 2.8.x before 2.8.7, and 2.9.x before 2.9.1 allows remote attackers to inject arbitrary web script or HTML by leveraging absence of an external_format_text call in a web service.
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Analysis
by VulDB Data Team • 05/31/2022
The CVE-2015-3274 vulnerability represents a critical cross-site scripting flaw in the Moodle learning management system that affects multiple version branches including 2.6.11 and earlier, 2.7.x versions before 2.7.9, 2.8.x versions before 2.8.7, and 2.9.x versions before 2.9.1. This vulnerability specifically resides within the user_get_user_details function located in the user/lib.php file, making it a core component of the platform's user management infrastructure. The flaw stems from the absence of proper output sanitization when processing user data through web services, creating an exploitable entry point for malicious actors to execute arbitrary scripts within the context of affected user sessions.
The technical implementation of this vulnerability demonstrates a classic XSS weakness where user input is not properly escaped or filtered before being rendered in web pages. The vulnerability occurs because the user_get_user_details function fails to invoke the external_format_text call that would normally sanitize user-provided content before it is exposed to web browsers. This omission allows attackers to inject malicious JavaScript code or HTML content through user profile data or other input fields that are subsequently processed by this function. The impact is particularly severe because the vulnerability operates through web services, which means that malicious code can be executed even when users are not directly interacting with the Moodle interface but rather through automated service calls or API integrations.
From an operational perspective, this vulnerability presents significant risks to Moodle deployments since it enables remote code execution capabilities that could lead to session hijacking, data theft, or complete system compromise. Attackers can exploit this flaw to inject malicious scripts that persist in user profiles and are executed whenever other users view those profiles or interact with the affected web services. The vulnerability's presence across multiple version lines indicates a systemic issue in the codebase that required coordinated patching efforts across different release branches. Security professionals should note that this vulnerability aligns with CWE-79, which specifically addresses cross-site scripting flaws in software applications, and it represents a common attack vector that appears frequently in web applications lacking proper input validation and output sanitization mechanisms.
The exploitation of CVE-2015-3274 follows established patterns found in the ATT&CK framework's web application attack methodologies, particularly in the credential access and persistence phases. Attackers can leverage this vulnerability to establish footholds within Moodle environments by injecting malicious code that can harvest user credentials or redirect users to phishing sites. The remediation strategy involves implementing proper input validation and output escaping mechanisms, specifically ensuring that all user-provided data is properly sanitized before being processed through the user_get_user_details function. Organizations should prioritize immediate patching of affected versions and implement additional security measures such as web application firewalls, content security policies, and regular security audits to prevent similar vulnerabilities from emerging in other components of their Moodle installations. The vulnerability also underscores the importance of proper code review practices and automated security testing in preventing such flaws from reaching production environments.