CVE-2013-4525 in Moodle
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in mod/quiz/report/responses/responses_table.php in Moodle through 2.2.11, 2.3.x before 2.3.10, 2.4.x before 2.4.7, and 2.5.x before 2.5.3 allows remote authenticated users to inject arbitrary web script or HTML via an answer to a text-based quiz question.
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Analysis
by VulDB Data Team • 06/15/2017
The vulnerability described in CVE-2013-4525 represents a critical cross-site scripting flaw within the Moodle learning management system that affects multiple version branches including 2.2.x through 2.2.11, 2.3.x through 2.3.9, 2.4.x through 2.4.6, and 2.5.x through 2.5.2. This issue resides in the quiz responses reporting module at the file path mod/quiz/report/responses/responses_table.php, making it accessible to authenticated users who can manipulate quiz question responses. The vulnerability stems from inadequate input validation and output sanitization mechanisms that fail to properly escape or filter user-supplied content before rendering it within web pages. This particular flaw enables attackers with valid user accounts to inject malicious scripts or HTML code into quiz responses, which then execute in the context of other users' browsers when they view the quiz results report. The exploit requires authentication since only registered users can submit answers to quiz questions, but once exploited, the malicious code can target any user who accesses the vulnerable report functionality. The technical implementation of this vulnerability aligns with CWE-79 which specifically addresses cross-site scripting flaws in web applications where untrusted data is improperly incorporated into web pages without proper validation or escaping. From an operational perspective, this vulnerability poses significant risks to educational institutions relying on Moodle for their learning management needs, as it could enable attackers to steal session cookies, redirect users to malicious sites, or execute arbitrary commands within the browser context of authenticated users. The impact extends beyond simple data theft since malicious actors could potentially escalate privileges or gain unauthorized access to sensitive educational data through session hijacking techniques. The vulnerability's exploitation pathway follows ATT&CK technique T1566.001 which involves the use of malicious inputs to execute code in web applications, making it particularly dangerous in educational environments where users may not be security-aware and could inadvertently trigger the exploit through normal quiz-taking activities. Organizations using affected Moodle versions should immediately implement mitigations including upgrading to patched versions, implementing strict input validation for quiz responses, and applying output encoding to prevent script execution in web contexts. Additional protective measures include monitoring user activity for suspicious quiz submissions, implementing web application firewalls, and conducting regular security assessments of educational platforms to identify similar vulnerabilities. The broader implications highlight the importance of robust input validation in web applications, particularly in educational software where user-generated content must be carefully sanitized to prevent exploitation of such vulnerabilities that could compromise entire institutional networks through targeted attacks on authenticated users.