CVE-2011-1765 in MediaWiki
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in MediaWiki before 1.16.5, when Internet Explorer 6 or earlier is used, allows remote attackers to inject arbitrary web script or HTML via an uploaded file accessed with a dangerous extension such as .shtml at the end of the query string, in conjunction with a modified URI path that has a %2E sequence in place of the . (dot) character. NOTE: this vulnerability exists because of an incomplete fix for CVE-2011-1578 and CVE-2011-1587.
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Analysis
by VulDB Data Team • 11/07/2021
The vulnerability described in CVE-2011-1765 represents a cross-site scripting flaw in MediaWiki versions prior to 1.16.5 that specifically targets users operating Internet Explorer 6 or earlier browsers. This security weakness stems from an inadequate patch for previously identified vulnerabilities, creating a persistent threat vector that attackers can exploit through carefully crafted file uploads and URI manipulation techniques. The vulnerability demonstrates the complexity of web application security where seemingly minor fixes can leave residual attack surfaces that malicious actors can leverage.
The technical mechanism of this vulnerability involves a sophisticated combination of file extension handling and URI parsing that exploits browser-specific behaviors in older Internet Explorer versions. Attackers can manipulate file uploads by appending dangerous extensions such as .shtml to query strings while simultaneously using URL encoding techniques where the dot character is replaced with %2E sequences in the URI path. This dual approach allows malicious scripts to bypass security checks that would normally prevent execution of potentially harmful content, particularly when the application processes these modified file paths through its content handling mechanisms.
The operational impact of this vulnerability extends beyond simple script injection, as it specifically targets the interaction between MediaWiki's file handling capabilities and Internet Explorer's security model. When exploited, this vulnerability allows remote attackers to execute arbitrary web scripts or HTML content within the context of affected users' browsers, potentially leading to session hijacking, data theft, or further exploitation of the compromised systems. The attack requires specific conditions including the use of Internet Explorer 6 or earlier, making it somewhat limited in scope but still significant given the prevalence of older browser versions in certain enterprise environments.
This vulnerability directly relates to CWE-79 which defines cross-site scripting as a critical weakness in web applications, and aligns with ATT&CK technique T1566 which covers spearphishing with a link, demonstrating how such flaws can be leveraged in social engineering campaigns. The incomplete fix for CVE-2011-1578 and CVE-2011-1587 highlights the importance of thorough vulnerability remediation processes and the potential for regression issues in security patches. Organizations should implement comprehensive browser compatibility testing and ensure that security updates are properly validated across all supported environments.
Mitigation strategies for this vulnerability require immediate implementation of the MediaWiki 1.16.5 security update which addresses the root cause of the issue through improved file extension validation and URI parsing mechanisms. Additionally, administrators should enforce strict content validation policies for file uploads, implement proper input sanitization for all user-supplied data, and consider deploying web application firewalls to detect and prevent exploitation attempts. The remediation process should also include comprehensive testing to ensure that the fix properly handles all combinations of file extensions and URI encoding techniques that could potentially bypass security controls, particularly in legacy browser environments where such vulnerabilities remain more prevalent.