CVE-2016-6211 in Drupal
Summary
by MITRE
The User module in Drupal 7.x before 7.44 allows remote authenticated users to gain privileges via vectors involving contributed or custom code that triggers a rebuild of the user profile form.
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Analysis
by VulDB Data Team • 04/13/2019
The vulnerability identified as CVE-2016-6211 represents a significant privilege escalation flaw within the Drupal content management system affecting version 7.x prior to 7.44. This issue resides within the User module and specifically targets authenticated users who can leverage contributed or custom code to manipulate the user profile form rebuild process. The vulnerability operates through a sophisticated vector that exploits the trust placed in module execution and form handling within the Drupal framework. According to CWE-264, this represents a permissions, privileges, and access control weakness where the system fails to properly validate or restrict access to administrative functions that should only be available to users with appropriate privileges.
The technical implementation of this vulnerability involves a carefully orchestrated sequence where authenticated users can manipulate form rebuild operations to execute arbitrary code or gain elevated privileges. When contributed or custom modules trigger a user profile form rebuild, the system's access control mechanisms fail to properly validate whether the user should have access to administrative functions. This flaw enables attackers to bypass normal security boundaries and potentially escalate their privileges to administrative levels. The vulnerability demonstrates a classic case of insufficient input validation combined with improper access control enforcement, allowing malicious actors to exploit the legitimate form rebuilding functionality for unauthorized access.
The operational impact of CVE-2016-6211 extends beyond simple privilege escalation, creating potential for widespread system compromise when exploited in environments where multiple users have access to contributed modules. Attackers can leverage this vulnerability to gain administrative control over entire Drupal installations, potentially leading to complete system compromise, data exfiltration, or the deployment of malicious code. The risk is particularly elevated in multi-user environments where users have the ability to install or modify contributed modules, as this creates multiple attack vectors for privilege escalation. Organizations running affected Drupal versions face significant exposure to unauthorized access and potential data breaches.
Mitigation strategies for this vulnerability require immediate patching to Drupal version 7.44 or later, which contains the necessary security fixes to prevent the unauthorized form rebuild operations. System administrators should also implement strict module management policies, limiting the ability of authenticated users to install or modify contributed modules. The principle of least privilege should be enforced by restricting user access to administrative functions and ensuring that only trusted administrators can modify system configurations. Additionally, monitoring and logging of form rebuild operations should be implemented to detect potential exploitation attempts, aligning with attack techniques documented in the MITRE ATT&CK framework under privilege escalation categories. Organizations should also consider implementing web application firewalls and security monitoring tools to detect anomalous behavior patterns that may indicate exploitation attempts.