CVE-2017-8896 in ownCloud Server
Summary
by MITRE
ownCloud Server before 8.2.12, 9.0.x before 9.0.10, 9.1.x before 9.1.6, and 10.0.x before 10.0.2 are vulnerable to XSS on error pages by injecting code in url parameters.
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Analysis
by VulDB Data Team • 10/27/2019
The vulnerability identified as CVE-2017-8896 represents a cross-site scripting flaw that affects multiple versions of the ownCloud server platform, specifically targeting error page handling mechanisms. This vulnerability allows attackers to inject malicious scripts into URL parameters that are subsequently displayed on error pages, creating a persistent XSS vector that can compromise user sessions and execute unauthorized actions. The affected versions span across the 8.2.x, 9.0.x, 9.1.x, and 10.0.x release lines, indicating a widespread issue that impacted the core functionality of the file sharing and synchronization platform. The vulnerability manifests when the server fails to properly sanitize user-supplied input that appears in error messages, creating an attack surface where malicious code can be executed in the context of a victim's browser session.
The technical implementation of this vulnerability stems from insufficient input validation and output encoding within the ownCloud server's error handling routines. When the server encounters an error condition, it typically displays error pages that may contain user-provided data from URL parameters without adequate sanitization. This flaw aligns with CWE-79, which specifically addresses cross-site scripting vulnerabilities arising from improper handling of untrusted data in web applications. The vulnerability can be exploited through crafted URLs containing malicious script payloads that are rendered on error pages, potentially enabling attackers to steal session cookies, redirect users to malicious sites, or perform actions on behalf of authenticated users. The attack vector is particularly concerning as it leverages legitimate server error conditions, making it difficult for users to distinguish between genuine system errors and maliciously crafted error pages.
The operational impact of this vulnerability extends beyond simple script execution, as it can lead to complete session hijacking and unauthorized access to sensitive data within the ownCloud environment. Attackers can craft malicious URLs that, when visited by authenticated users, cause the server to display attacker-controlled content on error pages, potentially leading to credential theft, data exfiltration, or privilege escalation. The vulnerability affects all users of the affected ownCloud versions, including administrators and regular users, making it a critical security concern for organizations relying on the platform for file sharing and collaboration. This XSS vulnerability can be exploited in conjunction with other attack techniques, potentially allowing attackers to establish persistent access to the system through session manipulation or by redirecting users to phishing pages that appear legitimate due to the error page context. The impact is particularly severe given that ownCloud serves as a platform for storing and sharing sensitive business and personal data, making the potential for data compromise significant.
Mitigation strategies for CVE-2017-8896 involve immediate patching of affected ownCloud installations to versions that properly sanitize user input in error handling scenarios. Organizations should implement comprehensive input validation and output encoding mechanisms across all server components, particularly focusing on error page generation and URL parameter handling. The recommended approach includes applying the security patches released by ownCloud for versions 8.2.12, 9.0.10, 9.1.6, and 10.0.2, which address the root cause of the vulnerability through proper input sanitization and output encoding. Additionally, implementing web application firewalls with XSS detection capabilities can provide an additional layer of protection, while regular security monitoring and code reviews should be conducted to identify similar vulnerabilities in other application components. The remediation process should also include user education regarding the risks of visiting suspicious URLs and the importance of maintaining updated software versions to prevent exploitation of known vulnerabilities. This vulnerability demonstrates the critical importance of proper input validation in web applications and aligns with ATT&CK technique T1211, which covers the exploitation of vulnerabilities in web applications through injection attacks.