CVE-2019-18612 in AbuseFilter Extension
Summary
by MITRE
An issue was discovered in the AbuseFilter extension through 1.34 for MediaWiki. Previously hidden (restricted) AbuseFilter filters were viewable (or their differences were viewable) to unprivileged users, thus disclosing potentially sensitive information.
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Analysis
by VulDB Data Team • 01/29/2024
The vulnerability identified as CVE-2019-18612 resides within the AbuseFilter extension of MediaWiki platforms, affecting versions through 1.34. This security flaw represents a critical access control weakness that undermines the confidentiality of sensitive filtering configurations. The issue manifests when restricted AbuseFilter filters, which should only be accessible to privileged users with appropriate administrative permissions, become visible to unprivileged users who lack proper authorization. This exposure occurs during both direct viewing of filter configurations and when users attempt to view differences between filter versions, creating multiple attack vectors for information disclosure.
The technical implementation of this vulnerability stems from inadequate authorization checks within the AbuseFilter extension's user interface and API endpoints. When users access filter management pages or compare different versions of filters, the system fails to properly verify whether the requesting user possesses the necessary privileges to view restricted filter data. This misconfiguration allows unauthorized users to potentially discover sensitive information about content filtering policies, including patterns, conditions, and rules that administrators have deliberately restricted from public view. The flaw operates at the application logic level where access control decisions are made, representing a direct violation of the principle of least privilege that should govern all security-sensitive operations.
The operational impact of this vulnerability extends beyond simple information disclosure, as it creates potential for abuse by malicious actors who might leverage the exposed filter information to craft content that circumvents existing protections or to understand the scope of content monitoring systems. Attackers could use this knowledge to identify gaps in filtering strategies, understand the types of content that are monitored, or even predict future filter updates. This information disclosure could enable more sophisticated attacks against the MediaWiki platform or facilitate social engineering attempts that exploit the knowledge of content restrictions and monitoring practices. The vulnerability particularly affects organizations that rely on MediaWiki for sensitive content management, where the exposure of filter configurations could reveal confidential information about content policies and monitoring procedures.
Organizations affected by CVE-2019-18612 should immediately implement the vendor-provided patch that addresses the access control validation issue within the AbuseFilter extension. The mitigation strategy involves ensuring that all filter viewing and comparison operations properly validate user permissions before displaying restricted content. Security teams should conduct comprehensive audits of their MediaWiki installations to identify any other extensions that might suffer from similar access control vulnerabilities. This vulnerability aligns with CWE-284 which describes inadequate access control mechanisms, and represents a clear violation of the ATT&CK technique T1078.004 related to valid accounts with insufficient privileges. Organizations should also consider implementing network-level monitoring to detect unusual access patterns that might indicate exploitation attempts, while maintaining regular security updates to prevent similar issues from emerging in other components of their MediaWiki infrastructure.