CVE-2017-8811 in MediaWiki
Summary
by MITRE
The implementation of raw message parameter expansion in MediaWiki before 1.27.4, 1.28.x before 1.28.3, and 1.29.x before 1.29.2 allows HTML mangling attacks.
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Analysis
by VulDB Data Team • 01/23/2021
The vulnerability identified as CVE-2017-8811 represents a critical security flaw in MediaWiki's handling of raw message parameter expansion mechanisms. This issue affects multiple versions of the popular wiki software including releases before 1.27.4, 1.28.3, and 1.29.2, making it a widespread concern for organizations relying on MediaWiki platforms. The vulnerability stems from insufficient input validation and sanitization within the message parameter expansion feature that processes raw content. When users submit content containing specially crafted parameters, the system fails to properly escape or filter HTML characters, creating opportunities for malicious actors to manipulate the rendering process. This flaw specifically impacts how MediaWiki processes parameters within raw messages, where parameter expansion occurs without adequate protection against cross-site scripting attacks. The vulnerability is categorized under CWE-79 as a Cross-Site Scripting (XSS) weakness, demonstrating the dangerous potential for attackers to inject malicious scripts into wiki pages. Attackers can exploit this vulnerability by crafting messages that contain HTML tags or JavaScript code within parameter expansions, which then get executed when other users view the affected pages. The operational impact extends beyond simple script execution, as successful exploitation could enable attackers to steal user sessions, deface wiki content, or redirect users to malicious websites. The attack vector leverages the legitimate parameter expansion functionality of MediaWiki, making it particularly dangerous as it bypasses typical security controls that might block direct HTML injection attempts. This vulnerability directly relates to the ATT&CK technique T1059.007 for Command and Scripting Interpreter: JavaScript, as it allows execution of malicious JavaScript code through the wiki's parameter expansion mechanism. Organizations using affected MediaWiki versions face significant risks to their content integrity and user security, as the vulnerability can be exploited by both authenticated and unauthenticated attackers depending on the wiki's configuration. The flaw essentially creates a pathway for HTML mangling attacks where attackers can manipulate the output rendering of wiki pages through parameter injection techniques. The remediation requires updating to patched versions of MediaWiki, with specific attention to version numbers 1.27.4, 1.28.3, and 1.29.2, which contain the necessary fixes for parameter sanitization. System administrators should prioritize immediate patching of affected installations, as the vulnerability's exploitation can occur without requiring special privileges or complex attack chains. Additionally, organizations should consider implementing additional security measures such as Content Security Policy headers and input validation at multiple layers to provide defense-in-depth against similar vulnerabilities. The vulnerability highlights the importance of proper parameter handling and output escaping in web applications, particularly in content management systems where user-generated content processing is essential. This issue serves as a reminder of how seemingly benign functionality can become a security risk when proper sanitization controls are missing from the implementation. The attack scenario typically involves a user submitting a message containing crafted parameters that, when expanded, result in malicious HTML or JavaScript being embedded in the rendered page. This creates a persistent threat that can affect all users who view the compromised content, making it particularly dangerous in collaborative environments where multiple users contribute to shared knowledge bases. The vulnerability's impact on user trust and platform integrity cannot be understated, as it enables attackers to compromise the perceived reliability of wiki content and potentially gain access to sensitive information through session hijacking or other related attacks.