CVE-2012-4402 in Moodle
Summary
by MITRE
webservice/lib.php in Moodle 2.1.x before 2.1.8, 2.2.x before 2.2.5, and 2.3.x before 2.3.2 does not properly restrict the use of web-service tokens, which allows remote authenticated users to run arbitrary external-service functions via a token intended for only one service.
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Analysis
by VulDB Data Team • 12/14/2021
The vulnerability identified as CVE-2012-4402 affects Moodle learning management systems version 2.1.x before 2.1.8, 2.2.x before 2.2.5, and 2.3.x before 2.3.2. This represents a critical authorization flaw in the web service component that undermines the security model designed to protect external service functions. The issue stems from insufficient validation of web-service tokens within the webservice/lib.php file, creating a privilege escalation path for authenticated users who should not have access to all available service endpoints.
The technical flaw manifests in the improper restriction of web-service token usage, where tokens intended for specific services are not adequately validated before execution. This allows malicious authenticated users to exploit the system by submitting a token that was originally designed for one particular service but then using it to invoke functions from other external services. The vulnerability operates at the application layer and leverages the existing authentication mechanism to bypass intended access controls, effectively creating a backdoor for unauthorized service invocation.
From an operational perspective, this vulnerability enables remote authenticated attackers to execute arbitrary external-service functions without proper authorization, potentially leading to data manipulation, information disclosure, or system compromise. The impact extends beyond simple privilege escalation as it allows attackers to leverage legitimate service endpoints to perform actions that should be restricted to authorized users only. This creates a significant risk for organizations relying on Moodle for educational content management and user authentication, as attackers can exploit this weakness to gain broader access to system resources and user data.
The vulnerability aligns with CWE-284, which addresses improper access control, and maps to ATT&CK technique T1078 for valid accounts and T1566 for phishing, as the attack requires valid authentication credentials. Organizations should implement immediate mitigations including applying the relevant security patches released by Moodle, reviewing and restricting web-service token usage policies, and monitoring for unauthorized service invocations. Additionally, administrators should consider implementing network segmentation and access controls to limit the potential impact of such vulnerabilities. The remediation process requires careful attention to ensure that token validation mechanisms are properly enforced across all web-service endpoints while maintaining legitimate functionality for authorized users.