CVE-2019-18987 in AbuseFilter Extension
Summary
by MITRE
An issue was discovered in the AbuseFilter extension through 1.34 for MediaWiki. Once a specific abuse filter has (accidentally or otherwise) been made public, its previous versions can be exposed, thus potentially disclosing private or sensitive information within the filter's definition.
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Analysis
by VulDB Data Team • 02/20/2024
The vulnerability identified as CVE-2019-18987 affects the AbuseFilter extension in MediaWiki versions through 1.34, representing a significant information disclosure flaw that undermines the confidentiality of filter definitions. This issue stems from inadequate access controls within the extension's version management system, where the exposure of previous filter versions occurs when a filter is made public. The flaw demonstrates a critical weakness in how the system handles sensitive data persistence and access permissions, particularly concerning administrative configurations that control user behavior and content moderation.
The technical implementation of this vulnerability resides in the AbuseFilter extension's handling of filter version history and access controls. When an abuse filter is modified and subsequently published, the system fails to properly restrict access to historical versions of that filter. This creates a scenario where previously private filter definitions, which may contain sensitive information such as user behavior patterns, content restrictions, or administrative strategies, become accessible to unauthorized users. The vulnerability essentially allows for privilege escalation through information disclosure, where users who should not have access to historical filter configurations can retrieve and analyze these potentially sensitive definitions.
From an operational impact perspective, this vulnerability poses substantial risks to organizations relying on MediaWiki for content management, particularly those in regulated industries or environments where content moderation policies contain sensitive information. The exposure of historical filter definitions could reveal strategic information about content monitoring approaches, user behavior analysis patterns, or institutional policies that were previously considered private. Attackers could potentially leverage this information to understand organizational content moderation strategies, identify potential security gaps in filtering mechanisms, or craft more sophisticated attacks against the system. The vulnerability affects the confidentiality aspect of the CIA triad, specifically targeting the protection of sensitive information within the MediaWiki environment.
The security implications extend beyond simple information disclosure to include potential abuse of the system's administrative capabilities and the exposure of organizational intelligence. Organizations using MediaWiki with the AbuseFilter extension may inadvertently expose their content management strategies, which could be valuable to competitors or malicious actors seeking to understand the system's defensive mechanisms. This vulnerability aligns with CWE-200 (Information Exposure) and represents a failure in access control mechanisms that should prevent unauthorized access to sensitive administrative configurations. The issue also relates to ATT&CK technique T1566 (Phishing) and T1078 (Valid Accounts) as attackers could use the exposed information to craft more targeted attacks or exploit legitimate access patterns.
Mitigation strategies should focus on implementing proper access controls for filter version history and ensuring that administrative configurations remain private even after publication. Organizations should upgrade to MediaWiki versions that address this vulnerability, typically those beyond 1.34 where the fix has been implemented. Additionally, administrators should conduct regular audits of their AbuseFilter configurations to ensure that sensitive information is not inadvertently exposed through version history. The implementation of role-based access controls and regular security assessments of MediaWiki extensions can help prevent similar vulnerabilities from occurring in other components of the system. System administrators should also consider implementing network-level controls and monitoring to detect unusual access patterns that might indicate exploitation attempts.