CVE-2015-2932 in MediaWiki
Summary
by MITRE
Incomplete blacklist vulnerability in MediaWiki before 1.19.24, 1.2x before 1.23.9, and 1.24.x before 1.24.2 allows remote attackers to inject arbitrary web script or HTML via an animated href XLink element.
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Analysis
by VulDB Data Team • 05/03/2022
The vulnerability identified as CVE-2015-2932 represents a critical security flaw in MediaWiki versions prior to the specified patches, specifically affecting releases before 1.19.24, 1.23.9, and 1.24.2. This issue manifests as an incomplete blacklist vulnerability that enables remote attackers to execute malicious code through crafted XLink elements within animated href attributes. The flaw resides in the wiki platform's handling of XML-based media elements, particularly those involving animated graphics and multimedia content that utilize xlink:href attributes for dynamic content referencing.
The technical implementation of this vulnerability stems from MediaWiki's insufficient filtering mechanisms for xlink:href elements within XML namespaces, particularly in animated graphics such as SVG files. When users upload or reference media files containing malicious xlink:href attributes, the system fails to properly validate or sanitize these elements against a comprehensive threat model. The incomplete blacklist approach means that while certain known dangerous patterns are filtered, numerous other attack vectors remain unaddressed, allowing attackers to craft malicious XLink elements that bypass existing security controls. This vulnerability specifically targets the XML parsing and rendering engine's handling of external references within animated content, creating a pathway for cross-site scripting attacks through the manipulation of xlink:href attributes.
The operational impact of this vulnerability extends beyond simple script injection, as it provides attackers with the capability to execute arbitrary web scripts and HTML content within the context of authenticated user sessions. This enables sophisticated attack scenarios including session hijacking, data exfiltration, and the potential for privilege escalation within the wiki environment. The vulnerability affects not only the end-user experience but also compromises the integrity of the entire wiki platform, as attackers can manipulate content to serve malicious payloads to other users. The exploitation requires minimal user interaction beyond viewing the affected content, making it particularly dangerous in collaborative environments where users frequently upload and reference multimedia files. This vulnerability directly maps to CWE-79, which describes cross-site scripting flaws, and can be leveraged as part of broader attack chains targeting web applications under the ATT&CK framework's T1059.007 technique for script execution.
Mitigation strategies for CVE-2015-2932 require immediate implementation of updated MediaWiki versions that contain proper sanitization of xlink:href attributes and comprehensive blacklist validation. Organizations should implement additional network-level protections including web application firewalls that can detect and block malicious XLink patterns, while also establishing robust content validation policies for uploaded media files. The solution involves enhancing the XML parsing engine to properly validate external references and implement a whitelist approach for xlink:href attributes rather than relying on incomplete blacklists. System administrators should also consider implementing automated scanning tools that can detect potentially malicious SVG files and other XML-based media content, while regular security audits should verify that all MediaWiki installations have been updated to patched versions. Additionally, user education regarding the risks of uploading untrusted media content and monitoring of suspicious file uploads can serve as supplementary defensive measures against exploitation attempts.