CVE-2012-4403 in Moodle
Summary
by MITRE
theme/yui_combo.php in Moodle 2.3.x before 2.3.2 does not properly construct error responses for the drag-and-drop script, which allows remote attackers to obtain the installation path by sending a request for a nonexistent resource and then reading the response.
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Analysis
by VulDB Data Team • 12/14/2021
The vulnerability identified as CVE-2012-4403 affects Moodle 2.3.x versions prior to 2.3.2, specifically within the theme/yui_combo.php component that handles drag-and-drop functionality. This issue represents a classic information disclosure vulnerability where the application fails to properly sanitize error responses, inadvertently revealing sensitive system information to remote attackers. The flaw occurs during the processing of requests for nonexistent resources within the YUI combo handler, which is part of Moodle's JavaScript framework integration for enhanced user interface capabilities.
The technical implementation of this vulnerability stems from improper error handling within the theme/yui_combo.php script that manages the combination and delivery of YUI JavaScript libraries. When a malicious actor sends a request for a non-existent resource, the system's error response construction mechanism fails to strip or obscure the installation path information that should remain hidden from external parties. This misconfiguration allows attackers to extract the absolute file path where Moodle is installed on the server, which constitutes sensitive system information that could aid in subsequent exploitation attempts. The vulnerability specifically affects the drag-and-drop script functionality and demonstrates poor input validation and error response construction practices.
The operational impact of this vulnerability extends beyond simple information disclosure, as the revealed installation path provides attackers with crucial reconnaissance data that can inform more sophisticated attacks. Knowledge of the exact server path structure enables threat actors to better understand the system architecture, potentially facilitating directory traversal attacks, path-based privilege escalation, or targeted exploitation of other vulnerabilities within the same installation. This information disclosure vulnerability aligns with CWE-200, which categorizes improper error handling as a significant security concern that can expose system internals to unauthorized parties. The vulnerability also maps to ATT&CK technique T1212, which focuses on data manipulation and information gathering through error message analysis.
Mitigation strategies for CVE-2012-4403 require immediate implementation of the security patch released by Moodle for version 2.3.2, which properly handles error responses and prevents path disclosure. Organizations should ensure all Moodle installations are updated to the patched versions, with particular attention to the theme/yui_combo.php file and related JavaScript handling components. Additionally, system administrators should implement comprehensive error handling practices that sanitize all error responses to prevent information leakage, including the use of generic error messages that do not reveal system paths or internal structures. Network-level protections such as web application firewalls can provide additional layers of defense by monitoring for suspicious request patterns and potentially blocking malicious attempts to probe for path information, though the primary defense remains the application-level patch.