CVE-2017-16196 in quickserver
Summary
by MITRE
quickserver is a simple static file server. quickserver 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 CVE-2017-16196 vulnerability affects quickserver, a lightweight static file server implementation that serves files directly from the filesystem without proper input validation. This directory traversal flaw represents a critical security weakness that allows remote attackers to access arbitrary files on the server's filesystem by manipulating URL parameters. The vulnerability stems from the server's failure to sanitize user-supplied input, specifically the path components that are processed to determine which files to serve. When an attacker includes "../" sequences in the URL, the server processes these traversal patterns without adequate validation, effectively allowing access to files outside the intended document root directory.
This vulnerability maps directly to CWE-22, which describes improper limitation of a pathname to a restricted directory, commonly known as path traversal or directory traversal attacks. The flaw operates at the application layer where the server fails to implement proper input sanitization and path resolution mechanisms. The attack vector is particularly dangerous because it requires no authentication and can be executed through simple URL manipulation, making it highly exploitable in automated scanning scenarios. The vulnerability exists in the core file serving logic where the server accepts user-provided paths and directly uses them to locate filesystem resources without proper validation or normalization.
The operational impact of this vulnerability is severe as it can lead to complete compromise of the server's filesystem. An attacker can access sensitive files including configuration files, database files, application source code, and potentially system files that contain credentials or other confidential information. The vulnerability enables unauthorized data exfiltration, which can result in data breaches and intellectual property theft. Additionally, the ability to traverse directories may allow attackers to access system files, potentially leading to privilege escalation or further compromise of the underlying operating system. The impact extends beyond simple information disclosure, as the vulnerability can facilitate more sophisticated attacks including remote code execution if combined with other weaknesses in the server environment.
Mitigation strategies for CVE-2017-16196 should focus on implementing proper input validation and path sanitization mechanisms. Organizations should ensure that all user-provided paths are normalized and validated against a whitelist of allowed directories before file access is granted. The server implementation should enforce strict path resolution that prevents traversal beyond the intended document root. Security measures should include implementing proper directory traversal protection through the use of secure file access APIs that prevent path manipulation attacks. Additionally, network segmentation and access controls should be implemented to limit the potential impact of such vulnerabilities. The mitigation approach aligns with ATT&CK technique T1083, which focuses on discovering system information through directory listing and file access techniques that attackers would employ to exploit this type of vulnerability. Regular security updates and code reviews should be conducted to prevent similar issues in other applications and to ensure that the server configuration properly restricts filesystem access to authorized directories only.