CVE-2016-3170 in Drupal
Summary
by MITRE
The "have you forgotten your password" links in the User module in Drupal 7.x before 7.43 and 8.x before 8.0.4 allow remote attackers to obtain sensitive username information by leveraging a configuration that permits using an email address to login and a module that permits logging in.
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Analysis
by VulDB Data Team • 10/05/2018
The vulnerability described in CVE-2016-3170 represents a critical information disclosure issue within the Drupal content management system that affects versions prior to 7.43 and 8.0.4. This flaw specifically targets the user authentication module's password recovery functionality, creating an avenue for remote attackers to systematically enumerate valid usernames through a process known as account enumeration. The vulnerability stems from the configuration flexibility that allows users to log in using either their username or email address, combined with the absence of proper rate limiting or validation controls during the password reset process.
The technical exploitation of this vulnerability occurs when an attacker interacts with the "have you forgotten your password" functionality and submits email addresses or usernames to the system. When the system processes these requests, it provides different responses depending on whether the submitted identifier corresponds to an existing user account. This differential response behavior enables attackers to determine which email addresses or usernames are registered within the system, effectively creating a user enumeration attack vector. The flaw is particularly dangerous because it operates at the authentication layer where attackers can leverage legitimate system functionality to gather intelligence about valid user accounts.
The operational impact of this vulnerability extends beyond simple information disclosure as it significantly weakens the overall security posture of Drupal installations. Attackers can use the gathered username information to conduct targeted phishing campaigns, brute force attacks, or social engineering operations against specific users. This vulnerability aligns with CWE-200, which addresses "Information Disclosure," and represents a classic example of how authentication mechanisms can inadvertently leak sensitive information when not properly secured against timing or response-based attacks. The vulnerability also maps to ATT&CK technique T1087.001, which covers "Account Discovery: Local Account," as it enables attackers to discover valid account identifiers that can then be used for further exploitation.
Organizations running affected Drupal versions should immediately implement the security patches released by the Drupal project to address this vulnerability. The recommended mitigation includes upgrading to Drupal 7.43 or later, or Drupal 8.0.4 and later versions where the vulnerability has been resolved. Additionally, system administrators should consider implementing rate limiting controls on password reset requests, disabling the password reset functionality if not required, and monitoring for unusual patterns in authentication requests. The vulnerability demonstrates the importance of proper input validation and response handling in authentication systems, where seemingly benign functionality can become a security risk when not properly secured against information leakage attacks. Security teams should also conduct thorough assessments of their authentication mechanisms to ensure similar vulnerabilities do not exist in other components of their web applications.