CVE-2009-1507 in Nodeaccess Userreference
Summary
by MITRE
The Node Access User Reference module 5.x before 5.x-2.0-beta4 and 6.x before 6.x-2.0-beta6, a module for Drupal, interprets an empty CCK user reference as a reference to the anonymous user, which might allow remote attackers to bypass intended access restrictions to read or modify a node.
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Analysis
by VulDB Data Team • 12/09/2017
The vulnerability identified as CVE-2009-1507 affects the Node Access User Reference module within the Drupal content management system, specifically impacting versions 5.x prior to 5.x-2.0-beta4 and 6.x prior to 6.x-2.0-beta6. This module serves as a critical component for managing access controls and user references within Drupal sites, particularly when integrating with CCK (Content Construction Kit) user reference fields that define which users can access specific content nodes. The flaw stems from the module's improper handling of empty user reference fields, creating a security boundary that can be exploited by malicious actors to circumvent intended access controls.
The technical implementation of this vulnerability occurs when a CCK user reference field is left empty or null within a content node configuration. Rather than properly handling this empty state or rejecting the access attempt, the Node Access User Reference module interprets an empty reference as a reference to the anonymous user account. This behavior fundamentally undermines the access control mechanism because it allows any user, including unauthenticated visitors, to gain access to content that should be restricted to specific authenticated users or user groups. The module's flawed logic essentially transforms a deliberate access restriction into an unintended open access point, creating a privilege escalation scenario where unauthorized users can bypass authentication requirements.
From an operational perspective, this vulnerability presents a significant risk to Drupal sites that rely on user reference-based access controls for content protection. Attackers can exploit this flaw to read or modify nodes that contain sensitive information, user data, or administrative content that should only be accessible to authorized personnel. The impact extends beyond simple information disclosure, as the vulnerability allows for potential data manipulation and modification of content that users would normally be restricted from altering. This represents a direct violation of the principle of least privilege and can lead to complete compromise of content integrity and confidentiality within affected Drupal installations.
The vulnerability aligns with CWE-284, which addresses improper access control, and demonstrates how improper handling of null or empty values can create security weaknesses in access control systems. From an attack framework perspective, this issue maps to multiple ATT&CK techniques including T1078 for valid accounts and T1566 for credential harvesting, as attackers can leverage this vulnerability to gain unauthorized access to restricted content. The flaw essentially creates a backdoor mechanism that bypasses normal authentication processes, making it particularly dangerous for sites with sensitive content or user management systems. Organizations should prioritize immediate patching of affected versions and implement additional monitoring for unauthorized access attempts to nodes that should be restricted.
The remediation strategy involves upgrading to the patched versions of the Node Access User Reference module, specifically 5.x-2.0-beta4 and 6.x-2.0-beta6, which properly handle empty user reference fields. Administrators should also conduct thorough audits of existing access control configurations to identify any potential exploitation that may have occurred prior to patching. Additional defensive measures include implementing proper input validation for user reference fields, monitoring access logs for unusual patterns, and ensuring that all Drupal modules are kept up to date with the latest security patches. Organizations should also consider implementing additional access control layers beyond the vulnerable module to provide defense in depth against similar vulnerabilities in the future.