CVE-2011-4590 in Moodle
Summary
by MITRE
The web services implementation in Moodle 2.0.x before 2.0.6 and 2.1.x before 2.1.3 does not properly consider the maintenance-mode state and account attributes during login attempts, which allows remote authenticated users to bypass intended access restrictions by connecting to a webservice server.
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Analysis
by VulDB Data Team • 02/18/2019
The vulnerability identified as CVE-2011-4590 resides within the web services implementation of Moodle learning management system versions 2.0.x prior to 2.0.6 and 2.1.x prior to 2.1.3. This security flaw represents a critical authorization bypass issue that fundamentally undermines the platform's access control mechanisms. The vulnerability specifically affects the authentication and authorization processes that occur when users attempt to connect to Moodle's web service endpoints, creating a scenario where legitimate security controls can be circumvented by authenticated users.
The technical root cause of this vulnerability stems from the improper handling of maintenance mode states and account attributes during the web service login process. When Moodle operates in maintenance mode, it should typically restrict access to certain functionalities and prevent unauthorized operations. However, the flawed implementation fails to properly validate these critical state conditions when users attempt to authenticate through web services. This oversight occurs at the authentication layer where the system should verify that the user account is active, not suspended, and that the platform is not in maintenance mode before granting access to web service resources.
From an operational perspective, this vulnerability enables remote authenticated users to bypass intended access restrictions that are typically enforced during maintenance periods or when specific account attributes are in effect. Attackers can exploit this weakness to gain unauthorized access to web service endpoints that should normally be restricted, potentially leading to data exposure, privilege escalation, or unauthorized modifications to course content and user information. The impact extends beyond simple unauthorized access as it undermines the integrity of the entire Moodle platform's security architecture and can compromise sensitive educational data.
The vulnerability aligns with CWE-284, which addresses improper access control in software implementations, and demonstrates characteristics consistent with ATT&CK technique T1078 for valid accounts and T1566 for credential harvesting. Organizations running affected Moodle versions face significant risk of unauthorized access to their educational platforms, potentially exposing student records, course materials, and administrative functions. The flaw particularly affects institutions that rely on Moodle's web services for integration with other systems or automated processes, as these endpoints become vulnerable to exploitation during maintenance periods when access controls are normally tightened.
Mitigation strategies should focus on immediate patching to the latest available Moodle versions that address this vulnerability. Organizations must ensure that all instances of Moodle are updated to versions 2.0.6 or later for 2.0.x releases, and 2.1.3 or later for 2.1.x releases. Additionally, administrators should implement strict monitoring of web service access patterns and consider implementing additional access controls beyond the default Moodle configuration. Network-level controls such as firewall rules and access control lists can provide additional defense-in-depth measures, while regular security audits should verify that maintenance mode states are properly enforced across all web service endpoints. The vulnerability serves as a reminder of the critical importance of proper access control implementation in web service architectures and the necessity of thorough testing of authentication flows during maintenance operations.