CVE-2017-6931 in Drupal
Summary
by MITRE
In Drupal versions 8.4.x versions before 8.4.5 the Settings Tray module has a vulnerability that allows users to update certain data that they do not have the permissions for. If you have implemented a Settings Tray form in contrib or a custom module, the correct access checks should be added. This release fixes the only two implementations in core, but does not harden against other such bypasses. This vulnerability can be mitigated by disabling the Settings Tray module.
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Analysis
by VulDB Data Team • 02/10/2023
The vulnerability identified as CVE-2017-6931 affects Drupal 8.4.x versions prior to 8.4.5 and specifically targets the Settings Tray module. This module provides a user interface component that allows administrators to configure various settings directly within the page context. The flaw represents a significant access control bypass issue that undermines the fundamental security principles of role-based access control that Drupal implements. The vulnerability stems from insufficient access validation within the module's form handling mechanisms, allowing unauthorized users to manipulate configuration data that should be restricted to specific user roles. This represents a direct violation of the principle of least privilege and could potentially enable privilege escalation attacks.
The technical implementation of this vulnerability occurs within the Settings Tray module's form processing logic where proper access checks are either missing or incorrectly implemented. When users interact with forms presented through the Settings Tray interface, the system fails to validate whether the requesting user possesses the appropriate permissions to modify the specific configuration data being accessed. This flaw creates an avenue for attackers to bypass normal access controls and modify system settings that should be restricted to privileged users. The vulnerability is classified under CWE-284, which specifically addresses improper access control, and aligns with ATT&CK technique T1068, which covers local privilege escalation through improper access controls. The issue manifests when the module processes form submissions without performing adequate permission verification against the user's role and capabilities.
The operational impact of this vulnerability extends beyond simple unauthorized data modification, as it potentially enables attackers to gain deeper system access and compromise the integrity of the Drupal installation. An attacker who can exploit this vulnerability might be able to alter critical system configurations, modify user permissions, or potentially escalate privileges to gain administrative access. The risk is particularly elevated in environments where multiple users with varying permission levels interact with the system, as the vulnerability could allow lower-privilege users to perform actions typically restricted to administrators. This vulnerability also represents a potential vector for persistent access, as attackers could modify configuration settings to maintain their access privileges over time. The impact is further compounded by the fact that this vulnerability affects core functionality rather than third-party modules, making it more difficult to isolate and remediate.
The Drupal security team addressed this vulnerability by implementing proper access checks within the two core implementations that were affected by this issue. However, the fix does not provide comprehensive protection against similar bypasses in custom or contributed modules that may implement the Settings Tray functionality. Organizations that have extended or modified the Settings Tray module in their custom implementations must conduct thorough security reviews to ensure proper access controls are in place. The recommended mitigation strategy includes disabling the Settings Tray module entirely if it is not essential for operations, as this provides the most straightforward path to eliminate the vulnerability. Additionally, administrators should ensure all custom modules that utilize the Settings Tray functionality implement proper access validation checks and adhere to Drupal's security best practices. The vulnerability highlights the importance of comprehensive security testing and the need for continuous monitoring of third-party integrations that may introduce access control weaknesses into the system architecture.