CVE-2016-6332 in MediaWiki
Summary
by MITRE
MediaWiki before 1.23.15, 1.26.x before 1.26.4, and 1.27.x before 1.27.1, when $wgBlockDisablesLogin is true, might allow remote attackers to obtain sensitive information by leveraging failure to terminate sessions when a user account is blocked.
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Analysis
by VulDB Data Team • 09/18/2020
MediaWiki is a widely deployed open source wiki software platform that powers numerous websites including wikipedia and various enterprise documentation systems. The vulnerability described in CVE-2016-6332 represents a critical security flaw in the platform's user authentication and session management mechanisms. This issue specifically affects versions prior to the mentioned patched releases, creating a persistent security risk for organizations relying on MediaWiki for their content management needs. The vulnerability stems from improper session handling when user accounts are blocked, creating a potential information disclosure vector that could be exploited by remote attackers.
The technical flaw manifests when the MediaWiki configuration parameter $wgBlockDisablesLogin is set to true, which is a common security setting designed to prevent blocked users from accessing the system. However, the implementation contains a critical oversight where user sessions are not properly terminated when accounts are blocked, allowing previously authenticated users to maintain access to the system even after their accounts have been administratively disabled. This creates a session hijacking scenario where attackers who have previously compromised legitimate user accounts or who have obtained valid session tokens can continue to operate within the system despite being blocked. The vulnerability is classified under CWE-617, which addresses reachable assertions and the improper handling of session state information, making it particularly concerning for systems where user authentication is paramount.
The operational impact of this vulnerability extends beyond simple privilege escalation as it fundamentally undermines the security model of the wiki platform. Attackers can leverage this flaw to maintain persistent access to systems, potentially leading to unauthorized content modification, data exfiltration, or further exploitation of the compromised environment. The vulnerability is particularly dangerous in collaborative environments where multiple users have access to sensitive information, as blocked users who maintain active sessions can continue to view restricted content or perform actions within the system. This issue directly relates to ATT&CK technique T1078 which covers valid accounts and the abuse of legitimate credentials for persistence and privilege escalation.
Organizations using affected MediaWiki versions should immediately implement the available patches and updates to address this vulnerability. System administrators should verify that their MediaWiki installations have been updated to versions 1.23.15, 1.26.4, or 1.27.1 respectively, depending on their current version. Additionally, security teams should review existing user sessions and implement session invalidation procedures for all users, particularly those who may have been blocked or compromised. The remediation process should include comprehensive testing to ensure that session termination works correctly when accounts are blocked, as well as monitoring for any suspicious activity that might indicate exploitation attempts. Regular security audits should verify that configuration settings like $wgBlockDisablesLogin are properly implemented and that the underlying session management system correctly handles account status changes. Organizations should also consider implementing additional security controls such as session timeout mechanisms and multi-factor authentication to provide defense in depth against similar vulnerabilities that may exist in other components of their wiki infrastructure.