CVE-2017-6925 in Drupal
Summary
by MITRE
In versions of Drupal 8 core prior to 8.3.7; There is a vulnerability in the entity access system that could allow unwanted access to view, create, update, or delete entities. This only affects entities that do not use or do not have UUIDs, and entities that have different access restrictions on different revisions of the same entity.
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Analysis
by VulDB Data Team • 01/09/2021
The vulnerability identified as CVE-2017-6925 represents a critical access control flaw within Drupal 8 core systems prior to version 8.3.7. This issue specifically targets the entity access system, which governs how users interact with different types of content within the Drupal platform. The vulnerability stems from improper handling of access restrictions when entities lack universally unique identifiers, creating potential pathways for unauthorized users to bypass intended security controls. The flaw affects a specific subset of entities that do not utilize UUIDs, making it particularly concerning for systems that rely on traditional entity identification methods rather than the more robust unique identifier approach. Organizations using older Drupal 8 versions face significant risks when managing content that requires different access levels across various revisions, as the system fails to properly enforce these distinctions.
The technical implementation of this vulnerability occurs within Drupal's entity access subsystem where the platform fails to properly validate access permissions when dealing with entities that lack UUIDs. This flaw particularly manifests when entities have different access restrictions applied to different revisions of the same content item, creating a scenario where users might gain access to content they should not be authorized to view, create, update, or delete. The underlying issue lies in how the access control system processes entity revision data without proper UUID validation, allowing malicious actors to exploit the inconsistency in access enforcement. This vulnerability operates at the core architectural level of Drupal's content management system, making it particularly dangerous as it affects fundamental access control mechanisms rather than isolated modules or components. The flaw essentially creates a bypass condition where the system's permission checking logic becomes ineffective for certain entity types, particularly those without UUIDs.
From an operational impact perspective, this vulnerability exposes organizations to significant data integrity and confidentiality risks. Unauthorized users could potentially view sensitive content, modify existing entities, create new content they should not be permitted to access, or delete critical information from the system. The vulnerability's scope is particularly concerning for organizations that manage content with varying access levels across different revisions, such as legal documents, medical records, or proprietary business information. The impact extends beyond simple information disclosure to include potential data corruption or complete system compromise if attackers can leverage this access to escalate privileges or manipulate core system functionality. Security teams must consider the implications for audit trails and compliance requirements, as unauthorized access to entity revisions could compromise regulatory compliance and organizational security policies. This vulnerability particularly affects content management scenarios where revision control is essential, making it a critical concern for organizations with complex content governance requirements.
Mitigation strategies for CVE-2017-6925 primarily focus on immediate system updates and architectural considerations. The most effective solution involves upgrading to Drupal 8.3.7 or later versions where the vulnerability has been addressed through enhanced access control validation mechanisms. Organizations should implement comprehensive patch management processes to ensure all Drupal installations receive timely updates and security fixes. Additionally, security teams should conduct thorough assessments of their entity access configurations, particularly focusing on entities that do not utilize UUIDs and those requiring different access restrictions across revisions. The vulnerability aligns with CWE-284, which addresses improper access control in software systems, and can be mapped to ATT&CK technique T1078 for valid accounts and T1496 for resource hijacking. Organizations should also consider implementing additional monitoring and logging controls around entity access events to detect potential exploitation attempts. Regular security audits of content management systems and access control configurations help identify and remediate similar vulnerabilities before they can be exploited by malicious actors.