CVE-2013-2031 in MediaWiki
Summary
by MITRE
MediaWiki before 1.19.6 and 1.20.x before 1.20.5 allows remote attackers to conduct cross-site scripting (XSS) attacks, as demonstrated by a CDATA section containing valid UTF-7 encoded sequences in a SVG file, which is then incorrectly interpreted as UTF-8 by Chrome and Firefox.
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Analysis
by VulDB Data Team • 01/10/2022
The vulnerability identified as CVE-2013-2031 represents a critical cross-site scripting weakness in MediaWiki versions prior to 1.19.6 and 1.20.x before 1.20.5. This flaw exploits the improper handling of character encoding during SVG file processing, creating a pathway for remote attackers to inject malicious scripts into web applications. The vulnerability specifically targets the interpretation of UTF-7 encoded sequences within CDATA sections of SVG files, demonstrating how encoding mismanagement can lead to security breaches in content management systems. The issue stems from the browser's incorrect interpretation of UTF-7 sequences as UTF-8, which allows attackers to bypass security mechanisms designed to prevent script execution.
The technical implementation of this vulnerability involves the manipulation of SVG file uploads where attackers can embed UTF-7 encoded sequences within CDATA sections that contain valid UTF-7 encoded content. When these SVG files are processed by MediaWiki and subsequently rendered in browsers like Chrome and Firefox, the browsers interpret the UTF-7 encoded sequences as UTF-8, effectively transforming the encoded malicious content into executable script code. This encoding confusion occurs because the MediaWiki application fails to properly sanitize or validate the character encoding of uploaded SVG files, allowing the UTF-7 sequences to be interpreted as regular text rather than encoded data. The vulnerability is particularly dangerous because SVG files are commonly used for graphical content and are often processed without strict security validation, making them ideal vectors for XSS attacks.
The operational impact of CVE-2013-2031 extends beyond simple script injection, potentially allowing attackers to execute malicious code in the context of affected users' browsers. This could enable session hijacking, credential theft, or redirection to malicious websites through the exploitation of the XSS vulnerability. The vulnerability affects not only the integrity of the MediaWiki application but also the security of all users interacting with the platform, as any user who views an affected SVG file could become compromised. The widespread use of MediaWiki in various organizations and websites means that this vulnerability could potentially impact a large number of users across different domains and applications. The attack vector is particularly insidious because SVG files are often considered safe content types and are frequently uploaded without additional security scrutiny, making the exploitation more likely to succeed.
Mitigation strategies for this vulnerability primarily involve upgrading to patched versions of MediaWiki, specifically versions 1.19.6 and 1.20.5 or later, which contain proper encoding validation and sanitization mechanisms. Organizations should implement comprehensive content validation for all uploaded SVG files, including strict character encoding checks and removal of potentially dangerous CDATA sections. The implementation of Content Security Policy headers can provide additional protection against script execution, while proper input sanitization should be enforced at multiple levels including file upload validation, parsing, and rendering stages. Security teams should also conduct regular vulnerability assessments of their MediaWiki installations and implement monitoring for suspicious file uploads, particularly focusing on SVG files that may contain unusual encoding sequences. This vulnerability aligns with CWE-79 which addresses cross-site scripting flaws, and relates to ATT&CK technique T1059.007 for script injection attacks, emphasizing the need for robust input validation and encoding handling in web applications.