CVE-2019-10047 in Pydio
Summary
by MITRE
A stored XSS vulnerability exists in the web application of Pydio through 8.2.2 that can be exploited by levering the file upload and file preview features of the application. An authenticated attacker can upload an HTML file containing JavaScript code and afterwards a file preview URL can be used to access the uploaded file. If a malicious user shares an uploaded HTML file containing JavaScript code with another user of the application, and tricks an authenticated victim into accessing a URL that results in the HTML code being interpreted by the web browser, then the included JavaScript code is executed under the context of the victim user session.
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Analysis
by VulDB Data Team • 09/25/2023
The vulnerability CVE-2019-10047 represents a critical stored cross-site scripting flaw within Pydio web applications version 8.2.2 and earlier. This vulnerability resides in the application's file upload and preview functionality, creating a persistent security weakness that allows attackers to execute malicious code within the context of authenticated user sessions. The flaw operates through a combination of file upload capabilities and subsequent preview mechanisms that fail to properly sanitize user-provided content, particularly HTML files containing embedded JavaScript code.
The technical implementation of this vulnerability stems from insufficient input validation and output encoding within Pydio's file handling system. When authenticated users upload HTML files containing malicious JavaScript payloads, the application stores these files without adequate sanitization processes. Subsequently, when other users access the file preview functionality, the stored HTML content is rendered directly in the browser without proper context-aware escaping or content security measures. This creates a persistent XSS vector where the malicious JavaScript executes in the victim's browser session with the privileges and permissions of the authenticated user.
The operational impact of this vulnerability extends beyond simple code execution, as it enables attackers to perform session hijacking, credential theft, and privilege escalation attacks. The vulnerability operates under the CWE-79 classification for cross-site scripting, specifically targeting stored XSS scenarios where malicious input is permanently stored on the target server. Attackers can craft sophisticated phishing campaigns by sharing malicious files with other users, who are then tricked into accessing preview URLs that trigger the execution of embedded JavaScript. This attack vector aligns with ATT&CK technique T1059.007 for command and scripting interpreter and T1566 for phishing, as it leverages both social engineering and technical exploitation.
The security implications of this vulnerability are particularly severe given that it requires only authentication to exploit, meaning that attackers need not compromise user credentials through traditional means. The attack chain begins with uploading a malicious HTML file, followed by social engineering to convince victims to access the preview URL, and concludes with the execution of arbitrary JavaScript code under the victim's authenticated session. This enables attackers to perform actions such as reading sensitive files, modifying user permissions, accessing other users' data, or even escalating privileges to administrative levels depending on the victim's access rights within the Pydio environment.
Mitigation strategies for CVE-2019-10047 should focus on implementing comprehensive input validation and output encoding mechanisms within the file upload and preview components of Pydio. Organizations should enforce strict content type validation for uploaded files, implement proper HTML sanitization before rendering user content, and utilize content security policies to prevent execution of unauthorized scripts. The most effective immediate solution involves upgrading to Pydio version 8.2.3 or later, which includes patches addressing the stored XSS vulnerability. Additionally, network-level security controls such as web application firewalls and intrusion detection systems should be configured to monitor for suspicious file upload patterns and potential XSS payloads, while user education regarding suspicious file sharing and preview access should be emphasized to reduce successful social engineering attacks.