CVE-2016-9451 in Drupal
Summary
by MITRE
Confirmation forms in Drupal 7.x before 7.52 make it easier for remote authenticated users to conduct open redirect attacks via unspecified vectors.
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Analysis
by VulDB Data Team • 06/10/2019
The vulnerability identified as CVE-2016-9451 affects Drupal 7.x content management systems prior to version 7.52, specifically targeting the confirmation forms implementation that governs user interactions within the platform. This flaw resides in the core Drupal architecture's handling of user confirmation workflows, particularly when users are directed through various forms and validation processes. The issue manifests in the way the system processes redirect parameters during authentication and confirmation sequences, creating opportunities for malicious actors to manipulate the redirect behavior.
The technical flaw stems from insufficient validation of redirect URLs within the confirmation form processing logic. When authenticated users navigate through Drupal's confirmation mechanisms, the system accepts redirect parameters without adequate sanitization or verification of their legitimacy. This vulnerability allows attackers to craft malicious URLs that appear to originate from legitimate Drupal interfaces while actually redirecting users to arbitrary external domains. The unspecified vectors mentioned in the description suggest that multiple pathways within the confirmation form system could be exploited, potentially including user registration flows, password reset procedures, and administrative confirmation processes.
The operational impact of this vulnerability extends beyond simple open redirect scenarios, creating significant risks for Drupal implementations that rely on user trust and authentication. Remote authenticated users can leverage this weakness to conduct phishing attacks by redirecting victims to malicious domains that mimic legitimate Drupal interfaces. The attack surface becomes particularly dangerous in environments where users frequently interact with confirmation forms, as the vulnerability can be exploited to harvest credentials, distribute malware, or perform social engineering campaigns. Organizations using vulnerable Drupal versions face potential reputational damage, data exposure risks, and compromised user trust when attackers successfully execute these redirect attacks.
Security professionals should implement immediate mitigations including upgrading to Drupal 7.52 or later versions where the vulnerability has been addressed through enhanced input validation and redirect parameter sanitization. The fix typically involves strengthening the validation logic in confirmation form handlers to ensure all redirect URLs are properly verified against a whitelist of trusted domains or undergo strict URL parsing to prevent malicious redirection. Organizations should also consider implementing additional network-level protections such as web application firewalls that can detect and block suspicious redirect patterns. From a compliance standpoint, this vulnerability aligns with CWE-601 open redirect weaknesses and can be mapped to ATT&CK technique T1566.001 for credential harvesting through phishing. The remediation process should include comprehensive testing of all confirmation form workflows to ensure that the patched validation logic properly handles edge cases and does not introduce regressions in legitimate user functionality.