CVE-2013-2123 in Nodeaccess Userreference Module
Summary
by MITRE
The Node access user reference module 6.x-3.x before 6.x-3.5 and 7.x-3.x before 7.x-3.10 for Drupal does not properly restrict access to content containing a user reference field when the author update/delete grants are enabled and the author s user account is deleted, which allows remote attackers to modify the content via unspecified vectors.
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Analysis
by VulDB Data Team • 03/18/2019
The vulnerability described in CVE-2013-2123 affects the Node access user reference module within Drupal CMS versions 6.x-3.x prior to 6.x-3.5 and 7.x-3.x prior to 7.x-3.10. This represents a critical access control flaw that undermines the security model of Drupal sites relying on user reference fields for content management. The vulnerability specifically targets scenarios where the author update and delete permissions are enabled alongside user reference fields, creating a dangerous condition that persists even after the original user account has been removed from the system.
The technical flaw stems from improper access restriction mechanisms within the module's handling of user reference fields when user accounts are deleted. When an author's account is removed from the system, the module fails to properly invalidate or revoke access permissions that were previously granted to that user for content they authored. This creates a scenario where deleted user accounts can still manipulate content through user reference fields, exploiting the module's inadequate cleanup of access control references. The unspecified vectors of attack suggest that multiple pathways exist for exploitation, potentially including direct API calls, form submissions, or indirect manipulation through related modules that interact with the user reference system.
The operational impact of this vulnerability extends beyond simple unauthorized content modification, as it represents a fundamental breakdown in Drupal's content access control architecture. Remote attackers can leverage this flaw to modify content that should be restricted to specific authors or roles, potentially leading to data integrity compromise, unauthorized publishing of content, or manipulation of user reference relationships. This vulnerability particularly affects Drupal sites implementing complex content management systems where user reference fields are extensively used for editorial workflows, content ownership tracking, and role-based access control. The persistence of access rights after account deletion creates a potential attack surface that could be exploited by malicious actors to maintain unauthorized access to content even after legitimate users have been removed from the system.
Mitigation strategies for this vulnerability require immediate patching of affected Drupal installations to versions 6.x-3.5 or 7.x-3.10 respectively, which contain the necessary access control fixes. Organizations should also implement comprehensive access control audits to identify and remediate any lingering permissions that may have been granted to deleted user accounts. The vulnerability aligns with CWE-284, which addresses improper access control, and maps to ATT&CK technique T1078 for valid accounts, as it allows attackers to maintain access through compromised user reference relationships. System administrators should consider implementing additional monitoring for content modification activities, particularly around user reference field changes, and establish regular audits of user account status and associated content permissions to prevent similar vulnerabilities from persisting in the environment.