CVE-2011-0047 in MediaWiki
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in MediaWiki before 1.16.2 allows remote attackers to inject arbitrary web script or HTML via crafted Cascading Style Sheets (CSS) comments, aka "CSS injection vulnerability."
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Analysis
by VulDB Data Team • 10/13/2021
The CVE-2011-0047 vulnerability represents a critical cross-site scripting flaw discovered in MediaWiki versions prior to 1.16.2, specifically targeting the application's handling of Cascading Style Sheets comments. This vulnerability falls under the CWE-79 category of Cross-Site Scripting, where the flaw allows remote attackers to inject malicious code through CSS comment fields. The vulnerability exploits the insecure processing of user-supplied input within CSS comment structures, creating a pathway for attackers to execute arbitrary web scripts or HTML code in the context of affected users' browsers. The issue stems from the MediaWiki application's insufficient sanitization of CSS comments, which are typically used for documentation purposes within CSS files but can be manipulated to contain malicious payloads when processed by the application's rendering engine.
The technical exploitation of this vulnerability occurs when attackers craft malicious CSS comments containing embedded JavaScript or HTML code within the CSS comment syntax. These comments are then processed by MediaWiki's CSS parser and rendered within the web application's output, causing the malicious code to execute in the victim's browser context. The attack vector specifically targets the CSS comment parsing mechanism, where the application fails to properly escape or validate comment content before rendering it to end users. This creates a persistent XSS scenario where the malicious code can be stored within the MediaWiki system and executed whenever affected pages are loaded, making the vulnerability particularly dangerous as it can affect multiple users simultaneously. The vulnerability is classified as a persistent XSS attack under the ATT&CK framework's T1566.001 technique, which focuses on the exploitation of web application vulnerabilities to inject malicious content.
The operational impact of CVE-2011-0047 extends beyond simple script execution, as it enables attackers to perform various malicious activities including session hijacking, data theft, and redirection to malicious sites. When successful, the vulnerability allows threat actors to steal user credentials, access sensitive information, or manipulate the application's functionality by executing code within the user's browser session. The vulnerability affects the integrity and confidentiality of the MediaWiki platform, potentially compromising the security of entire wiki installations where users may have elevated privileges or access to sensitive content. Organizations using vulnerable MediaWiki versions face significant risk of unauthorized access and data breaches, as the attack requires no special privileges from the attacker beyond the ability to submit CSS comments through the application's interface. This makes the vulnerability particularly concerning for collaborative environments where multiple users contribute content, as a single malicious comment can compromise all users of the affected system.
Mitigation strategies for CVE-2011-0047 focus primarily on upgrading to MediaWiki version 1.16.2 or later, which contains the necessary patches to address the CSS comment handling vulnerability. System administrators should implement comprehensive input validation and sanitization measures, ensuring that all user-supplied CSS content undergoes strict filtering before processing. The implementation of Content Security Policy headers can provide additional protection layers against XSS attacks by restricting the sources from which scripts can be executed. Organizations should also consider implementing web application firewalls to detect and block suspicious CSS comment patterns. Regular security audits and vulnerability assessments of MediaWiki installations are essential to identify and remediate similar issues before they can be exploited. The vulnerability serves as a reminder of the importance of proper input validation and the potential security implications of seemingly benign features like CSS comments, which should never be treated as trusted input in web applications. Organizations should also establish secure coding practices that emphasize the principle of least privilege and proper sanitization of all user-supplied content, particularly in environments where users can contribute styling elements to web applications.