CVE-2009-4527 in Shib Auth
Summary
by MITRE
The Shibboleth authentication module 5.x before 5.x-3.4 and 6.x before 6.x-3.2, a module for Drupal, does not properly remove statically granted privileges after a logout or other session change, which allows physically proximate attackers to gain privileges by using an unattended web browser.
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Analysis
by VulDB Data Team • 12/22/2017
The vulnerability identified as CVE-2009-4527 affects the Shibboleth authentication module for Drupal, specifically versions 5.x prior to 5.x-3.4 and 6.x prior to 6.x-3.2. This security flaw represents a critical session management weakness that exploits the improper handling of privileges during authentication transitions. The vulnerability resides in how the module manages user sessions and privilege escalation, creating a persistent security risk that can be exploited by attackers with physical access to a victim's device.
The technical root cause of this vulnerability stems from inadequate session cleanup mechanisms within the Shibboleth authentication module. When users log out or experience session changes, the module fails to properly revoke statically granted privileges that were assigned during the authentication process. This improper privilege removal creates a window where an attacker can exploit the system by simply using an unattended web browser left open after a legitimate user has logged out. The flaw operates at the intersection of session management and privilege escalation, where the system does not properly invalidate previously granted access rights upon session termination.
This vulnerability presents significant operational impact for organizations relying on Drupal with Shibboleth authentication, particularly in environments where physical security controls are insufficient. The attack vector requires only physical proximity to an unattended device, making it particularly dangerous in shared workspaces, public terminals, or environments where users leave their browsers open. The security implications extend beyond simple privilege escalation to encompass potential data breaches, unauthorized system modifications, and compromise of sensitive information that could be accessed through the retained privileges.
The vulnerability aligns with CWE-285, which addresses improper authorization in authentication systems, and demonstrates characteristics consistent with ATT&CK technique T1548.003, which covers abuse of Sudo or similar privileges. Organizations using affected Drupal versions should prioritize immediate patching to address this flaw, as the vulnerability can be exploited without requiring network access or advanced technical skills from the attacker. The remediation process involves upgrading to patched versions of the Shibboleth module, implementing additional session management controls, and establishing proper user education regarding browser security practices. Security teams should also consider implementing automated session timeout mechanisms and monitoring for unusual privilege usage patterns to detect potential exploitation attempts.
The broader implications of this vulnerability highlight the importance of comprehensive session management in web applications, particularly those handling authentication and authorization functions. Organizations should review their authentication module configurations and ensure proper privilege cleanup procedures are in place. This vulnerability serves as a reminder that authentication systems must properly handle all session lifecycle events, including logout, timeout, and session invalidation, to prevent persistent privilege retention that could be exploited by attackers with physical access to systems.