CVE-2017-6923 in Drupal
Summary
by MITRE
In Drupal 8.x prior to 8.3.7 When creating a view, you can optionally use Ajax to update the displayed data via filter parameters. The views subsystem/module did not restrict access to the Ajax endpoint to only views configured to use Ajax. This is mitigated if you have access restrictions on the view. It is best practice to always include some form of access restrictions on all views, even if you are using another module to display them.
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Analysis
by VulDB Data Team • 12/16/2022
The vulnerability identified as CVE-2017-6923 represents a critical access control flaw within the Drupal 8 content management system affecting versions prior to 8.3.7. This issue specifically targets the views subsystem which is responsible for creating dynamic content displays and data retrieval mechanisms. The flaw exists in how Drupal handles Ajax endpoints for views, creating a potential pathway for unauthorized users to access restricted data through manipulated filter parameters. The vulnerability stems from insufficient authorization checks at the Ajax endpoint level, allowing attackers to bypass normal access controls that should prevent unauthorized data retrieval.
Drupal's views module provides powerful functionality for creating customized content displays and data filtering capabilities. When Ajax is enabled for views, the system generates dynamic endpoints that can update displayed data in real-time based on user input parameters. The technical flaw occurs because the views subsystem fails to validate whether the requesting user has proper authorization to access the specific Ajax endpoint before processing the request. This oversight means that any authenticated user could potentially access Ajax endpoints of views that are configured for Ajax updates, even if those views contain sensitive data or are restricted to specific user roles.
The operational impact of this vulnerability extends beyond simple information disclosure, as it can enable attackers to perform unauthorized data enumeration and potentially extract sensitive information from restricted views. The vulnerability is particularly concerning because it operates at the application level and can be exploited by users who may not have direct administrative privileges. Even when access restrictions are properly configured on individual views, the Ajax endpoint bypass allows attackers to circumvent these protections through crafted requests. This creates a scenario where an attacker could systematically probe different filter parameters to gather information about the underlying data structure, user roles, or content relationships within the system.
The vulnerability aligns with CWE-285, which addresses improper authorization issues in software systems, and can be mapped to ATT&CK technique T1078 for valid accounts and T1213 for data from information repositories. Organizations using Drupal 8 prior to version 8.3.7 face significant risk of unauthorized data access, particularly in environments where sensitive information is exposed through views. The mitigation strategy requires immediate patching to version 8.3.7 or later, but also emphasizes the importance of implementing robust access control practices. Security teams should conduct thorough reviews of all views within their Drupal installations to ensure proper access restrictions are in place, regardless of whether Ajax functionality is enabled. Additionally, implementing network-level controls such as web application firewalls and monitoring for unusual Ajax endpoint access patterns can provide additional defense-in-depth measures against exploitation attempts.
The broader implications of this vulnerability highlight the critical importance of proper access control implementation in web applications, particularly in content management systems where multiple users interact with dynamic data retrieval mechanisms. The flaw demonstrates how seemingly minor configuration oversight can create significant security risks, emphasizing the need for comprehensive security testing and validation of access control mechanisms. Organizations should implement regular security audits of their Drupal installations, focusing on view configurations and Ajax endpoint access controls. The vulnerability also underscores the importance of maintaining up-to-date software versions and following security best practices such as principle of least privilege and defense-in-depth strategies to protect against similar issues in the future.