CVE-2009-4520 in Commentreference
Summary
by MITRE
The CCK Comment Reference module 5.x before 5.x-1.2 and 6.x before 6.x-1.3, a module for Drupal, allows remote attackers to bypass intended access restrictions and read comments by using the autocomplete path.
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Analysis
by VulDB Data Team • 01/26/2019
The CVE-2009-4520 vulnerability affects the CCK Comment Reference module in Drupal versions 5.x before 5.x-1.2 and 6.x before 6.x-1.3, representing a significant access control flaw that undermines the security posture of Drupal-based web applications. This vulnerability specifically targets the module's autocomplete functionality, which is designed to provide users with suggestions when referencing comments within content management systems. The flaw allows remote attackers to bypass intended access restrictions and gain unauthorized access to comment data through manipulation of the autocomplete path parameter. The vulnerability stems from insufficient input validation and access control checks within the module's implementation, creating an avenue for privilege escalation and information disclosure.
The technical nature of this vulnerability aligns with CWE-284, which addresses improper access control, and demonstrates how module-level security flaws can compromise the entire Drupal platform. When attackers exploit this vulnerability, they can construct specific requests to the autocomplete endpoint that bypass the normal authentication and authorization checks. This allows unauthorized users to retrieve comment data that should be restricted to authenticated users or specific roles. The module's autocomplete feature typically serves to enhance user experience by suggesting available comments, but the implementation fails to properly verify whether the requesting user has appropriate permissions to access the target comment data. This represents a classic case of insufficient authorization checking where the system assumes that legitimate autocomplete requests are automatically authorized without proper validation.
The operational impact of CVE-2009-4520 extends beyond simple information disclosure, as it can enable attackers to gather sensitive data about user interactions, content relationships, and potentially uncover internal system structures. In Drupal environments where comment references are used for content management, this vulnerability could expose private discussions, user-generated content, or business-sensitive information that should remain protected. The remote nature of the attack means that exploitation does not require physical access to the system or local network privileges, making it particularly dangerous for web applications. Attackers can leverage this vulnerability through standard web browser interactions or automated tools, potentially leading to broader reconnaissance activities or additional attacks that build upon the initial information gathering.
Organizations running affected Drupal versions should prioritize immediate patching to address this vulnerability, as the CCK Comment Reference module is commonly used across numerous Drupal installations. The recommended mitigation strategy involves upgrading to the patched versions 5.x-1.2 and 6.x-1.3, which include proper access control enforcement for the autocomplete functionality. Security teams should also implement network-level restrictions and monitoring to detect unusual autocomplete requests that might indicate exploitation attempts. Additionally, this vulnerability highlights the importance of module security reviews and proper access control implementation in content management systems, as third-party modules can introduce critical security gaps that affect the entire platform. The incident serves as a reminder that even seemingly benign features like autocomplete can become security risks when proper access controls are not implemented, aligning with ATT&CK technique T1078 for valid accounts and T1566 for credential access through web application attacks.