CVE-2010-3685 in Drupal
Summary
by MITRE
The OpenID module in Drupal 6.x before 6.18, and the OpenID module 5.x before 5.x-1.4 for Drupal, violates the OpenID 2.0 protocol by not checking for reuse of openid.response_nonce values, which allows remote attackers to bypass authentication by leveraging an assertion from an OpenID provider.
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Analysis
by VulDB Data Team • 09/25/2021
The vulnerability described in CVE-2010-3685 represents a critical security flaw in the OpenID authentication implementation within Drupal content management systems. This issue affects Drupal 6.x versions prior to 6.18 and Drupal 5.x versions prior to 5.x-1.4, specifically within the OpenID module that handles external authentication protocols. The flaw stems from the module's failure to properly validate openid.response_nonce values, which are essential components in the OpenID 2.0 protocol designed to prevent replay attacks and ensure the uniqueness of authentication assertions.
The technical core of this vulnerability lies in the improper handling of nonce values that are integral to the OpenID 2.0 specification. In a proper OpenID implementation, each authentication assertion must contain a unique nonce value that serves as a timestamp and prevents attackers from reusing previously valid authentication responses. When the Drupal OpenID module fails to verify that these nonce values have not been previously used, it creates an exploitable condition where malicious actors can capture a valid authentication assertion from a legitimate OpenID provider and replay it to gain unauthorized access to user accounts.
This vulnerability directly violates the OpenID 2.0 protocol specification and can be categorized under CWE-347, which addresses improper verification of cryptographic signatures or authentication tokens. The attack vector allows remote adversaries to bypass authentication mechanisms by leveraging captured authentication assertions, effectively enabling unauthorized access to Drupal sites that rely on OpenID for user authentication. The operational impact extends beyond simple account compromise, as successful exploitation could lead to complete system compromise if attackers gain administrative access through the compromised OpenID accounts.
The security implications of this vulnerability align with techniques documented in the MITRE ATT&CK framework under the authentication bypass category, specifically targeting the credential access and privilege escalation domains. Attackers can exploit this weakness without requiring any special privileges or access to the system itself, making it particularly dangerous for web applications that depend on external authentication providers. The vulnerability demonstrates a fundamental flaw in the cryptographic validation process within the Drupal OpenID module, where the system fails to maintain proper state tracking of authentication tokens.
Mitigation strategies for this vulnerability require immediate patching of affected Drupal installations to versions 6.18 or later for Drupal 6.x and 5.x-1.4 or later for Drupal 5.x, which contain the necessary fixes to properly validate nonce reuse. Organizations should also implement additional security measures such as monitoring for unusual authentication patterns and ensuring that all OpenID providers are properly configured to generate unique nonce values. The fix addresses the root cause by implementing proper nonce validation that prevents the reuse of previously accepted authentication tokens, thereby restoring compliance with the OpenID 2.0 protocol requirements and eliminating the attack surface that allowed this specific class of authentication bypass.