CVE-2011-4304 in Moodle
Summary
by MITRE
The chat functionality in Moodle 2.0.x before 2.0.5 and 2.1.x before 2.1.2 allows remote authenticated users to discover the name of any user via a beep operation.
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Analysis
by VulDB Data Team • 12/05/2021
The vulnerability identified as CVE-2011-4304 resides within the chat component of Moodle learning management systems, specifically affecting versions prior to 2.0.5 and 2.1.2. This issue represents a significant information disclosure flaw that undermines user privacy and system security. The vulnerability manifests through the chat beep operation, which is designed as a simple notification mechanism allowing users to alert others when they are available for conversation. However, the implementation contains a critical design flaw that exposes user identification information to unauthorized parties.
The technical mechanism behind this vulnerability involves the improper handling of user identification data within the chat system's beep functionality. When an authenticated user initiates a beep operation, the system should only notify the target user of the incoming message without revealing sensitive identification details. Instead, the vulnerable implementation inadvertently includes user name information in the response, allowing malicious actors to enumerate valid user accounts within the system. This occurs because the system fails to properly validate or sanitize the user identification data before transmitting it during the beep operation, creating an information leak that directly violates fundamental security principles of least privilege and data minimization.
The operational impact of this vulnerability extends beyond simple information disclosure, as it creates a vector for user enumeration attacks that can be leveraged by threat actors to build comprehensive user profiles for subsequent attacks. Attackers can systematically test the beep functionality to identify valid usernames, potentially combining this information with other reconnaissance techniques to target specific users for phishing campaigns, credential stuffing attacks, or social engineering operations. The vulnerability affects the confidentiality aspect of the CIA triad, as it violates the principle that sensitive user information should remain protected from unauthorized access. This issue particularly impacts educational institutions that rely on Moodle for their learning management needs, as it could compromise the privacy of students, faculty, and staff members.
From a cybersecurity framework perspective, this vulnerability aligns with CWE-200, which addresses "Information Exposure," and represents a clear violation of the principle that systems should not reveal more information than necessary. The issue also maps to ATT&CK technique T1087.001, "Account Discovery: Local Account," as it enables attackers to discover valid user accounts within the system. Additionally, the vulnerability demonstrates poor input validation and output sanitization practices that are commonly addressed by security controls such as those outlined in the OWASP Top Ten and NIST Cybersecurity Framework. The affected Moodle versions were particularly susceptible because they lacked proper access controls and data filtering mechanisms within their chat implementation, allowing authenticated users to perform operations that should have been restricted to prevent information leakage.
Mitigation strategies for this vulnerability primarily focus on implementing proper access controls and output validation within the chat system. Organizations should immediately upgrade to patched versions of Moodle 2.0.5 or 2.1.2, which contain the necessary fixes to prevent unauthorized information disclosure. System administrators should also implement network-level monitoring to detect unusual patterns in chat operations that might indicate exploitation attempts. Additional protective measures include configuring proper user access controls to limit chat functionality to authorized users only, implementing rate limiting on chat operations to prevent automated enumeration attacks, and conducting regular security assessments of learning management systems. The vulnerability serves as a reminder of the importance of proper input validation and the principle that all system responses should be carefully sanitized to prevent information leakage. Security teams should also consider implementing comprehensive logging of chat operations to detect potential exploitation attempts and maintain audit trails for security incident response activities.