CVE-2015-2266 in Moodle
Summary
by MITRE
message/index.php in Moodle through 2.5.9, 2.6.x before 2.6.9, 2.7.x before 2.7.6, and 2.8.x before 2.8.4 does not consider the moodle/site:readallmessages capability before accessing arbitrary conversations, which allows remote authenticated users to obtain sensitive personal-contact and unread-message-count information via a modified URL.
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Analysis
by VulDB Data Team • 04/15/2022
The vulnerability identified as CVE-2015-2266 affects Moodle versions through 2.5.9, 2.6.x before 2.6.9, 2.7.x before 2.7.6, and 2.8.x before 2.8.4, specifically within the message/index.php component. This represents a critical access control flaw that undermines the security model of the learning management system by allowing authenticated users to bypass intended permission boundaries. The vulnerability stems from insufficient validation of user capabilities when processing requests for conversation data, creating a path for privilege escalation through manipulated web requests.
The technical implementation flaw resides in the message/index.php script which fails to properly verify whether the authenticated user possesses the required moodlesitereadallmessages capability before allowing access to conversation data. This capability should restrict access to message conversations to authorized personnel only, typically administrators or users with specific roles. When users manipulate URLs to access conversation endpoints, the system does not validate whether the requesting user has legitimate authorization to view the target conversation data, resulting in unauthorized information disclosure.
The operational impact of this vulnerability extends beyond simple information disclosure, as it enables attackers to gather sensitive personal contact information and unread message counts from conversations they should not have access to. This information can include email addresses, names, and other personally identifiable information of users within the Moodle environment. The vulnerability is particularly concerning because it operates at the application level and can be exploited by any authenticated user, making it accessible to both malicious insiders and external attackers who have gained initial access to the system. This information can be leveraged for social engineering attacks, targeted phishing campaigns, or further exploitation attempts.
This vulnerability maps directly to CWE-284, which describes improper access control mechanisms, and aligns with ATT&CK technique T1078 for valid accounts and T1566 for phishing attacks. The flaw represents a classic case of insufficient authorization checking where the application assumes that authenticated users should have access to all conversation data without proper capability validation. Organizations using affected Moodle versions face significant risk of data exposure and potential privacy violations. The vulnerability demonstrates the importance of implementing proper capability-based access controls and validating user permissions at every point of data access within web applications. Organizations should immediately implement the vendor-provided patches and consider conducting comprehensive security audits of their Moodle installations to identify similar authorization flaws that might exist in other components of the system.
The remediation approach involves applying the official security patches released by Moodle for the affected versions, which properly implement capability checks before allowing access to conversation data. System administrators should also review and tighten the configuration of user capabilities, ensuring that the moodlesitereadallmessages permission is restricted to appropriate administrative roles only. Additionally, implementing network-level monitoring and access control logging can help detect and prevent exploitation attempts of this vulnerability. Regular security assessments and penetration testing should be conducted to identify potential authorization bypass opportunities in web applications, particularly in systems that handle sensitive user data.