CVE-2009-4301 in Moodle
Summary
by MITRE
mnet/lib.php in Moodle 1.8 before 1.8.11 and 1.9 before 1.9.7, when MNET services are enabled, does not properly check permissions, which allows remote authenticated servers to execute arbitrary MNET functions.
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Analysis
by VulDB Data Team • 08/28/2021
The vulnerability identified as CVE-2009-4301 affects Moodle learning management systems version 1.8 before 1.8.11 and 1.9 before 1.9.7, specifically within the mnet/lib.php component. This issue arises when MNET services are enabled, creating a critical permission validation flaw that enables remote authenticated servers to execute arbitrary MNET functions. The vulnerability stems from inadequate access control mechanisms within the MNET framework, which is designed to facilitate secure communication between Moodle instances across different servers. When MNET services are active, the system should enforce strict permission checks to ensure that only authorized remote servers can invoke specific functions. However, the flaw in mnet/lib.php fails to properly validate these permissions, allowing malicious actors who have gained authentication credentials on remote servers to escalate their privileges and execute unauthorized functions.
The technical implementation of this vulnerability involves the failure of proper authorization checks within the MNET communication layer. The mnet/lib.php file, which handles MNET library functions, does not adequately verify the credentials or permissions of remote servers attempting to execute functions. This creates a path where authenticated but unauthorized remote servers can bypass normal access controls and execute functions that should be restricted to specific users or roles. The flaw essentially allows for a privilege escalation scenario where remote servers can perform operations that they should not be authorized to conduct, potentially leading to complete system compromise. The vulnerability is particularly dangerous because it operates at the communication layer, meaning that even if local system security is maintained, the remote communication channel remains vulnerable to exploitation.
The operational impact of this vulnerability is severe and multifaceted, as it can enable attackers to perform a wide range of malicious activities within the affected Moodle environment. Remote authenticated servers could potentially execute functions such as user creation, modification of course content, access to restricted resources, or even data exfiltration from the Moodle system. This vulnerability aligns with CWE-284, which describes improper access control, and represents a classic case of insufficient authorization checks. The attack vector requires that the attacker already has authentication credentials on a remote server, but once achieved, the vulnerability allows for lateral movement and privilege escalation within the Moodle ecosystem. The implications extend beyond simple unauthorized access, potentially enabling full system compromise and data breaches that could affect thousands of users within the affected learning management system.
Organizations using affected Moodle versions should immediately implement mitigations to address this vulnerability. The primary solution involves upgrading to Moodle versions 1.8.11 or 1.9.7, which contain the necessary patches to properly validate permissions within the MNET framework. Additionally, administrators should review and restrict MNET service configurations, disabling unnecessary services and ensuring that only trusted remote servers have access to MNET functions. Network-level restrictions can provide additional protection by limiting which external servers can communicate with the Moodle instance. The vulnerability demonstrates the importance of proper input validation and authorization checks as outlined in the OWASP Top Ten and aligns with ATT&CK technique T1078 for valid accounts and T1566 for malicious email attachments, as the exploitation requires authenticated access to remote systems. Security monitoring should be enhanced to detect unusual MNET communication patterns and unauthorized function execution attempts.