CVE-2011-3757 in Moodle
Summary
by MITRE
Moodle 2.0.1 allows remote attackers to obtain sensitive information via a direct request to a .php file, which reveals the installation path in an error message, as demonstrated by webservice/xmlrpc/locallib.php and certain other files.
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Analysis
by VulDB Data Team • 02/10/2019
The vulnerability described in CVE-2011-3757 represents a critical information disclosure flaw within Moodle version 2.0.1 that exposes installation paths through improper error handling mechanisms. This vulnerability falls under the category of CWE-200 - Information Exposure, where sensitive system information is inadvertently revealed to unauthorized users. The issue manifests when remote attackers can directly access specific php files within the Moodle installation, particularly those located in the webservice/xmlrpc/ directory structure, causing the application to display error messages that contain the full server path where Moodle is installed. This type of information exposure provides attackers with crucial reconnaissance data that can be leveraged for subsequent exploitation attempts.
The technical implementation of this vulnerability stems from inadequate input validation and error handling within Moodle's web service components. When the xmlrpc/locallib.php file or similar php scripts are accessed directly without proper authentication or parameter validation, the application fails to sanitize error messages appropriately. This allows the system to return verbose error information including the absolute file path to the installation directory, which is typically stored in the server's filesystem. The vulnerability is particularly concerning because it does not require any special privileges or authentication to exploit, making it accessible to any remote attacker with knowledge of the target system's structure.
The operational impact of this vulnerability extends beyond simple information disclosure, creating a significant risk for organizations using Moodle 2.0.1. The leaked installation paths can provide attackers with precise knowledge of the server environment, potentially revealing the operating system type, file structure, and even the specific version of the web server being used. This information can be used to tailor more sophisticated attacks against the system, such as exploiting known vulnerabilities in specific server configurations or conducting targeted attacks against the underlying infrastructure. The vulnerability also aligns with ATT&CK technique T1083 - File and Directory Discovery, as it enables adversaries to map the target system's file structure and identify potential attack vectors.
Organizations affected by this vulnerability should implement immediate mitigations to address the information disclosure risk. The primary recommendation involves ensuring that all php files within the Moodle installation are properly protected through access controls and that error messages are configured to not display sensitive system information in production environments. This includes implementing proper file permissions, configuring web server settings to prevent direct access to sensitive directories, and ensuring that error reporting is disabled or sanitized in production deployments. Additionally, system administrators should consider implementing web application firewalls to monitor and block direct requests to potentially vulnerable php files. The vulnerability demonstrates the importance of following secure coding practices and proper error handling mechanisms as outlined in industry standards such as the OWASP Top Ten and NIST Cybersecurity Framework, which emphasize the need for robust input validation and secure error handling to prevent information leakage that could compromise system security.