CVE-2018-14631 in Moodle
Summary
by MITRE
moodle before versions 3.5.2, 3.4.5, 3.3.8 is vulnerable to a boost theme - blog search GET parameter insufficiently filtered. The breadcrumb navigation provided by Boost theme when displaying search results of a blog were insufficiently filtered, which could result in reflected XSS if a user followed a malicious link containing JavaScript in the search parameter.
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Analysis
by VulDB Data Team • 05/16/2023
The vulnerability CVE-2018-14631 affects Moodle versions prior to 3.5.2, 3.4.5, and 3.3.8, specifically within the Boost theme's blog search functionality. This issue represents a classic reflected cross-site scripting vulnerability that exploits insufficient input validation in the breadcrumb navigation component. The flaw manifests when users navigate to blog search results pages where the search parameter is not properly sanitized before being rendered in the HTML output. The Boost theme, which serves as Moodle's default user interface for versions 3.5 and above, incorporates breadcrumb navigation that displays the search query string directly without adequate filtering mechanisms.
The technical implementation of this vulnerability stems from improper sanitization of user-supplied input within the search parameter handling mechanism. When a user follows a malicious link containing JavaScript code within the blog search GET parameter, the Boost theme's breadcrumb navigation renders this unsanitized input directly into the page's HTML structure. This creates an environment where malicious scripts can be executed in the context of the victim's browser session, potentially leading to session hijacking, credential theft, or redirection to malicious websites. The vulnerability classifies under CWE-79 which specifically addresses Cross-Site Scripting flaws, and it aligns with ATT&CK technique T1566.001 for initial access through malicious links.
The operational impact of this vulnerability extends beyond simple script execution as it can enable attackers to establish persistent malicious presence within Moodle environments. An attacker could craft links that, when clicked by authenticated users, would execute arbitrary JavaScript code in their browser context. This could result in unauthorized access to course materials, modification of user preferences, or even complete account compromise if session tokens are accessible. The vulnerability affects all users who have access to the blog search functionality, making it particularly dangerous in educational environments where users may click on links from untrusted sources. The reflected nature of the vulnerability means that attackers need to deliver malicious payloads through external channels, making it difficult to detect and prevent without proper input validation measures.
Mitigation strategies for this vulnerability require immediate implementation of proper input sanitization and output encoding mechanisms. Organizations should upgrade to Moodle versions 3.5.2, 3.4.5, or 3.3.8 where the vulnerability has been patched. The fix implemented in these versions involves ensuring that all user-supplied parameters passed to the breadcrumb navigation are properly escaped before rendering. Additional defensive measures include implementing Content Security Policy headers to limit script execution, conducting regular security audits of input handling mechanisms, and educating users about the risks of clicking suspicious links. Security teams should also consider implementing web application firewalls with XSS detection capabilities and monitor for anomalous patterns in search parameter usage that might indicate exploitation attempts. The vulnerability demonstrates the critical importance of input validation in web applications and the necessity of following secure coding practices that prevent malicious data from being rendered as executable code in user-facing interfaces.