CVE-2015-6727 in MediaWiki
Summary
by MITRE
The Special:DeletedContributions page in MediaWiki before 1.23.10, 1.24.x before 1.24.3, and 1.25.x before 1.25.2 allows remote attackers to determine if an IP is autoblocked via the "Change block" text.
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Analysis
by VulDB Data Team • 06/14/2022
The vulnerability identified as CVE-2015-6727 affects MediaWiki versions prior to specific patched releases, specifically targeting the Special:DeletedContributions page functionality. This issue represents a security flaw that exposes information about IP address blocking status to remote attackers, creating a potential reconnaissance opportunity. The vulnerability exists within the MediaWiki software's access control mechanisms and information disclosure handling, where the system inadvertently reveals whether an IP address is currently subject to autoblocking through the display of "Change block" text.
The technical flaw manifests in the way MediaWiki processes and displays information on the Special:DeletedContributions page. When an IP address is autoblocked, the system's response to user queries or page rendering includes specific text elements that indicate this autoblocking status. This information disclosure occurs without proper authorization checks, allowing attackers to perform passive reconnaissance to determine if specific IP addresses are currently blocked or subject to autoblocking mechanisms. The vulnerability operates at the application layer and requires no privileged access to exploit, making it particularly concerning for systems that may be under active monitoring or targeted by threat actors.
The operational impact of this vulnerability extends beyond simple information disclosure, as it provides attackers with intelligence that could be used in subsequent attacks. By identifying autoblocked IP addresses, adversaries can potentially avoid detection mechanisms or craft more sophisticated attack vectors that account for existing blocking policies. This vulnerability aligns with CWE-200, which addresses improper exposure of sensitive information, and represents a classic case of information leakage that can be leveraged for broader reconnaissance activities. The threat actors could use this information to determine the effectiveness of existing blocking measures or to plan attacks that account for IP address restrictions.
The vulnerability demonstrates weaknesses in MediaWiki's access control implementation and information flow management within the Special:DeletedContributions page. The system's failure to properly validate and sanitize output based on user permissions creates an information disclosure channel that can be exploited without authentication. This flaw represents a violation of the principle of least privilege, where system responses should not reveal information about access control status to unauthorized users. The attack vector is straightforward and requires only network access to the vulnerable MediaWiki instance, making it particularly dangerous in environments where such systems are publicly accessible.
Organizations affected by this vulnerability should implement immediate mitigations including upgrading to patched MediaWiki versions, specifically 1.23.10, 1.24.3, or 1.25.2 depending on their current version. The upgrade process should be carefully planned to ensure minimal disruption to services while addressing the information disclosure vulnerability. Additional defensive measures include implementing proper access controls, monitoring for suspicious queries to the Special:DeletedContributions page, and ensuring that all system responses properly validate user permissions before revealing sensitive information about access control status. The vulnerability also highlights the importance of regular security assessments and timely patch management to prevent similar issues from affecting other components of the MediaWiki ecosystem.