CVE-2017-16217 in fbr-client
Summary
by MITRE
fbr-client sends files through sockets via socket.io and webRTC. fbr-client is vulnerable to a directory traversal issue, giving an attacker access to the filesystem by placing "../" in the url.
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Analysis
by VulDB Data Team • 02/16/2020
The vulnerability identified as CVE-2017-16217 affects the fbr-client application which utilizes socket.io and webRTC protocols for file transmission over network connections. This client-side application processes file operations through socket communications, creating a potential attack surface where improper input validation can lead to severe security consequences. The flaw resides in the application's handling of file paths within URL parameters, specifically failing to properly sanitize or validate directory traversal sequences that could allow unauthorized access to system resources.
The technical implementation of this vulnerability stems from inadequate input validation mechanisms within the fbr-client's file handling routines. When the application processes file requests through URLs containing directory traversal sequences such as "../", it fails to properly validate or sanitize these path components before attempting file operations. This allows attackers to manipulate the file system access paths and potentially navigate to arbitrary directories on the server or client system. The vulnerability directly maps to CWE-22 which describes improper limitation of a pathname to a restricted directory, commonly known as directory traversal or path traversal attacks.
The operational impact of this vulnerability extends beyond simple unauthorized file access, as it can potentially lead to complete system compromise depending on the application's execution context and file system permissions. An attacker could leverage this vulnerability to access sensitive configuration files, system binaries, user data, or other critical resources that should remain protected from unauthorized access. The attack vector is particularly concerning because it operates through the legitimate file transmission channels that the application uses for its intended functionality, making detection more difficult and potentially allowing persistent access to compromised systems.
This vulnerability aligns with several ATT&CK techniques including T1059 Command and Scripting Interpreter and T1083 File and Directory Discovery, as attackers could use the directory traversal capability to enumerate system resources and potentially escalate privileges. The attack surface is further expanded when considering that socket.io and webRTC communications typically operate over network connections that may not be properly secured, potentially allowing remote attackers to exploit this vulnerability from external networks. Organizations using fbr-client applications should immediately implement input validation controls, implement proper path sanitization, and consider implementing additional network segmentation controls to limit the potential impact of such vulnerabilities.
Mitigation strategies should focus on implementing comprehensive input validation at multiple layers of the application architecture, including URL parameter sanitization, path validation, and proper access controls. The application should employ strict whitelist validation for file paths, implement proper authentication and authorization mechanisms, and utilize secure coding practices that prevent directory traversal attacks. Additionally, network-level protections such as firewalls, intrusion detection systems, and proper network segmentation can help reduce the attack surface and limit the potential impact of exploitation attempts. Regular security assessments and code reviews should be conducted to identify similar vulnerabilities in other components of the application ecosystem.