CVE-2011-1133 in Serendipity
Summary
by MITRE
Cross-Site Scripting (XSS) in Xinha, as included in the Serendipity package before 1.5.5, allows remote attackers to execute arbitrary code via plugins/ExtendedFileManager/backend.php.
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Analysis
by VulDB Data Team • 11/06/2019
The vulnerability CVE-2011-1133 represents a critical cross-site scripting flaw discovered in the Xinha WYSIWYG editor component that was integrated into the Serendipity publishing platform. This vulnerability specifically affects versions of Serendipity prior to 1.5.5, where the Xinha editor was bundled as part of the core functionality. The flaw manifests within the plugin architecture of the system, particularly in the ExtendedFileManager backend component which handles file management operations through the backend.php script. This represents a significant security risk as it allows malicious actors to inject and execute arbitrary code within the context of a user's browser session.
The technical implementation of this XSS vulnerability stems from inadequate input validation and output sanitization within the ExtendedFileManager's backend.php file. When users interact with the file management features of the editor, the application fails to properly sanitize user-supplied data that gets processed and rendered back to the browser. This creates an environment where attacker-controlled input can be executed as JavaScript code, effectively bypassing normal security boundaries. The vulnerability is classified under CWE-79 as a failure to sanitize user input before using it in a web page, and it aligns with ATT&CK technique T1566.001 for initial access through malicious web content.
The operational impact of this vulnerability extends beyond simple script execution, as it can enable attackers to perform a wide range of malicious activities including session hijacking, data theft, and privilege escalation. An attacker could leverage this vulnerability to inject malicious scripts that steal user credentials, redirect victims to phishing sites, or even install additional malware. The attack vector specifically targets the backend.php script which handles file operations, making it particularly dangerous as it could be exploited by users with limited privileges to gain elevated access. The vulnerability affects not only individual users but also the entire web application ecosystem, potentially compromising the integrity of the entire Serendipity installation.
Mitigation strategies for CVE-2011-1133 should focus on immediate patching of the affected Serendipity versions, with the recommended solution being an upgrade to version 1.5.5 or later where the vulnerability has been addressed. Organizations should implement comprehensive input validation measures across all user-facing interfaces, particularly those handling file uploads and management operations. The implementation of Content Security Policy headers can provide additional protection against XSS attacks by restricting script execution from unauthorized sources. Security teams should also consider implementing web application firewalls to detect and block suspicious requests targeting the vulnerable backend.php endpoint. Regular security assessments and penetration testing should be conducted to identify similar vulnerabilities in other components of the web application stack, as this type of flaw often indicates broader security gaps in input handling and output encoding practices.