CVE-2011-4278 in Moodle
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in the tag autocomplete functionality in Moodle 1.9.x before 1.9.11 and 2.0.x before 2.0.2 allows remote attackers to inject arbitrary web script or HTML via unspecified vectors.
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Analysis
by VulDB Data Team • 12/06/2021
The cross-site scripting vulnerability identified as CVE-2011-4278 affects Moodle learning management systems version 1.9.x prior to 1.9.11 and 2.0.x prior to 2.0.2, specifically within the tag autocomplete functionality. This vulnerability represents a critical security flaw that enables remote attackers to execute malicious web scripts or HTML code within the context of affected user sessions. The issue stems from inadequate input validation and output sanitization mechanisms within the tag handling components of the Moodle platform.
The technical flaw manifests in the tag autocomplete feature where user-supplied input is not properly sanitized before being rendered back to users. This allows attackers to craft malicious input containing script tags or other HTML elements that get executed when other users interact with the affected functionality. The vulnerability operates under CWE-79 which categorizes cross-site scripting flaws as weaknesses in input validation and output encoding. Attackers can exploit this by submitting specially crafted tags containing malicious payloads that persist in the system and execute when other users browse pages containing these tags.
The operational impact of this vulnerability extends beyond simple script execution as it can enable attackers to perform session hijacking, steal sensitive user information, manipulate data within the Moodle environment, or redirect users to malicious websites. The attack vector is particularly concerning because tag autocomplete functionality is commonly used and accessible to various user roles, including students and teachers who may not be security-aware. This makes the vulnerability exploitable across a wide range of users and contexts within the learning management system.
Security professionals should implement immediate mitigations including upgrading to patched versions of Moodle 1.9.11 or 2.0.2, which contain proper input sanitization measures for the tag autocomplete functionality. Organizations should also consider implementing additional security controls such as content security policies, regular security audits of user input handling, and comprehensive staff training on secure coding practices. The vulnerability aligns with ATT&CK technique T1566 which covers social engineering attacks through malicious web content, emphasizing the importance of proper input validation and output encoding in web applications.