CVE-2016-9450 in Drupal
Summary
by MITRE
The user password reset form in Drupal 8.x before 8.2.3 allows remote attackers to conduct cache poisoning attacks by leveraging failure to specify a correct cache context.
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Analysis
by VulDB Data Team • 06/10/2019
The vulnerability identified as CVE-2016-9450 affects Drupal 8.x versions prior to 8.2.3 and relates to a critical security flaw in the user password reset functionality. This issue enables remote attackers to execute cache poisoning attacks through a specific implementation weakness in how the system handles cache contexts during password reset operations. The vulnerability stems from the failure to properly specify cache contexts within the password reset form, creating opportunities for attackers to manipulate cached responses and potentially gain unauthorized access to user accounts.
The technical flaw manifests in the improper handling of cache contexts within Drupal's password reset mechanism. When users attempt to reset their passwords, the system should maintain separate cache entries for different user contexts to prevent cross-contamination of reset tokens and session data. However, the vulnerable implementation fails to correctly specify cache contexts, allowing attackers to poison the cache with malicious data that can be served to other users. This weakness operates at the application layer and specifically targets Drupal's caching subsystem, which is designed to improve performance by storing frequently accessed data in memory.
The operational impact of this vulnerability extends beyond simple privilege escalation as it creates a persistent threat vector that can be exploited repeatedly. Attackers can leverage this cache poisoning technique to intercept valid password reset tokens, potentially gaining access to user accounts without proper authentication. The vulnerability is particularly concerning because it operates silently in the background, with attackers able to manipulate cached responses without immediate detection. This type of attack can lead to account takeover scenarios, data breaches, and unauthorized access to sensitive user information, making it a significant concern for organizations relying on Drupal 8.x for their web applications.
Organizations affected by this vulnerability should immediately upgrade to Drupal 8.2.3 or later versions where the cache context handling has been properly implemented to prevent such attacks. The fix addresses the core issue by ensuring that password reset forms properly specify cache contexts, preventing the cross-contamination of cached data between different user sessions. Security teams should also implement monitoring for unusual password reset activities and consider additional authentication measures such as multi-factor authentication to mitigate potential exploitation. This vulnerability aligns with CWE-352, which covers Cross-Site Request Forgery (CSRF) attacks, and maps to ATT&CK technique T1190 for exploitation of web applications, emphasizing the need for comprehensive application security controls and regular patch management procedures.