CVE-2016-9466 in ownCloud Server
Summary
by MITRE
Nextcloud Server before 10.0.1 & ownCloud Server before 9.0.6 and 9.1.2 suffer from Reflected XSS in the Gallery application. The gallery app was not properly sanitizing exception messages from the Nextcloud/ownCloud server. Due to an endpoint where an attacker could influence the error message, this led to a reflected Cross-Site-Scripting vulnerability.
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Analysis
by VulDB Data Team • 11/22/2022
The vulnerability identified as CVE-2016-9466 represents a critical reflected cross-site scripting flaw within the Gallery application of Nextcloud Server versions prior to 10.0.1 and ownCloud Server versions prior to 9.0.6 and 9.1.2. This security weakness stems from inadequate input validation and output sanitization mechanisms within the web application's error handling system. The vulnerability specifically affects the gallery component which processes user-supplied data and displays it within the web interface, creating an attack surface where malicious payloads can be injected and executed in the context of other users' browsers.
The technical implementation of this vulnerability occurs through an endpoint that processes exception messages generated by the Nextcloud/ownCloud server. When the gallery application encounters an error condition during image processing or display operations, it retrieves exception data from the server and renders it directly within the user interface without proper sanitization. This flaw allows attackers to inject malicious script code into the error message parameters, which then gets reflected back to users who view the affected gallery page. The reflected nature of this XSS vulnerability means that the malicious payload must be delivered via a crafted URL or user interaction, making it particularly dangerous in social engineering scenarios.
The operational impact of this vulnerability extends beyond simple script execution, as it enables attackers to perform various malicious activities including session hijacking, credential theft, and data exfiltration. An attacker could craft a malicious URL containing script code that would be executed when a victim accesses the gallery application, potentially stealing session cookies or redirecting users to phishing sites. The vulnerability affects all users of the affected versions, making it a significant risk for organizations relying on these file sharing platforms for collaborative work environments. Given that the gallery application is commonly used for sharing media files, the attack surface is broad and the potential for user exposure is high.
Security mitigations for CVE-2016-9466 primarily involve upgrading to the patched versions of Nextcloud Server 10.0.1 and ownCloud Server 9.0.6 and 9.1.2, which include proper input sanitization and output encoding for error messages. Additionally, organizations should implement Content Security Policy headers to limit script execution within the application context, and consider implementing web application firewalls to detect and block suspicious payloads. The vulnerability aligns with CWE-79 which specifically addresses cross-site scripting flaws, and maps to ATT&CK technique T1203 for "Exploitation for Client Execution" within the context of web-based attack vectors. Regular security assessments and input validation reviews should be conducted to prevent similar vulnerabilities in other application components that handle user-supplied data and error reporting mechanisms.