CVE-2015-6730 in MediaWiki
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in thumb.php in MediaWiki before 1.23.10, 1.24.x before 1.24.3, and 1.25.x before 1.25.2 allows remote attackers to inject arbitrary web script or HTML via the f parameter, which is not properly handled in an error page, related to "ForeignAPI images."
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Analysis
by VulDB Data Team • 06/14/2022
The CVE-2015-6730 vulnerability represents a critical cross-site scripting flaw in MediaWiki's thumb.php script that affected multiple versions of the popular wiki platform. This vulnerability specifically targets the handling of the 'f' parameter within error pages, creating a pathway for remote attackers to inject malicious web scripts or HTML content. The issue stems from inadequate input validation and sanitization mechanisms that fail to properly process user-supplied data when generating error responses for ForeignAPI images, which are external image sources that MediaWiki can fetch and display. The vulnerability exists in versions prior to 1.23.10, 1.24.3, and 1.25.2, indicating a prolonged window of exposure across multiple release branches.
The technical exploitation of this vulnerability occurs when MediaWiki processes a request containing a malicious 'f' parameter value that is not properly escaped or validated before being rendered in an error page context. This allows attackers to inject arbitrary JavaScript code or HTML content that executes in the context of other users' browsers who view the affected error page. The flaw specifically relates to how the system handles error conditions when processing ForeignAPI images, where the error page generation does not adequately sanitize the parameter values before output rendering. The vulnerability is classified as a classic XSS flaw under CWE-79, which represents the common weakness in web applications where untrusted data is directly incorporated into web pages without proper validation or encoding.
The operational impact of this vulnerability extends beyond simple script injection, as it enables attackers to perform various malicious activities including session hijacking, credential theft, and redirection to malicious sites. When users encounter error pages related to ForeignAPI image processing, their browsers execute the injected malicious code, potentially compromising their sessions and allowing attackers to perform actions on their behalf. The vulnerability affects the integrity of the MediaWiki platform by enabling unauthorized code execution in user contexts, which can lead to data breaches, service disruption, and potential escalation to more serious attacks. This issue particularly impacts collaborative environments where multiple users interact with the wiki platform, as the attack surface expands with each user who might encounter the vulnerable error page.
Mitigation strategies for CVE-2015-6730 primarily involve upgrading to the patched versions of MediaWiki, specifically versions 1.23.10, 1.24.3, and 1.25.2 which contain proper input sanitization and validation for the 'f' parameter. Organizations should implement comprehensive input validation measures that properly escape or encode all user-supplied parameters before they are processed or rendered in web pages. The implementation of Content Security Policy headers can provide additional defense-in-depth measures by restricting script execution and limiting the impact of successful XSS attacks. Regular security audits and input validation testing should be conducted to identify similar vulnerabilities in other components of the MediaWiki platform or custom extensions. This vulnerability aligns with ATT&CK technique T1059.001 for command and scripting interpreter and T1566.001 for credential harvesting, highlighting the potential for privilege escalation and data compromise through successful exploitation. Organizations should also consider implementing web application firewalls to detect and block suspicious parameter values that could indicate XSS attack attempts, while maintaining proper logging and monitoring of error conditions to quickly identify exploitation attempts.