CVE-2017-16200 in uv-tj-demo
Summary
by MITRE
uv-tj-demo is a static file server. uv-tj-demo 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-2017-16200 affects uv-tj-demo, a static file server implementation that suffers from a critical directory traversal flaw. This type of vulnerability represents a fundamental security weakness in web applications that process user-supplied input to determine file access paths. The flaw allows attackers to manipulate URL parameters by injecting ../ sequences, which enables them to navigate outside the intended directory structure and access arbitrary files on the underlying filesystem. The vulnerability stems from inadequate input validation and sanitization within the file serving mechanism, where user-provided paths are directly incorporated into file system operations without proper security checks.
This directory traversal vulnerability maps directly to CWE-22, which specifically addresses improper limitation of a pathname to a restricted directory, commonly known as path traversal or directory traversal attacks. The attack vector exploits the lack of proper path normalization and validation, allowing malicious users to bypass access controls and potentially gain access to sensitive system files, configuration data, or other confidential information stored on the server. The impact is particularly severe because static file servers typically have broad file system access to serve content, making them attractive targets for attackers seeking to extract sensitive data or gain deeper system access. The vulnerability exists at the application layer and can be exploited through simple HTTP requests, making it easily accessible to attackers with minimal technical expertise.
The operational impact of this vulnerability extends beyond simple unauthorized file access, as it can enable attackers to potentially execute arbitrary code, escalate privileges, or conduct further reconnaissance activities within the compromised system. Attackers can leverage this vulnerability to access system configuration files, application source code, database files, or other sensitive resources that may contain credentials, encryption keys, or other valuable information. The vulnerability also aligns with several ATT&CK techniques including T1083 (File and Directory Discovery) and T1566 (Phishing with Malicious Attachment) when attackers use the access to gather information for more sophisticated attacks. The ease of exploitation means that even automated scanning tools can identify and exploit this vulnerability, making it a significant risk for systems running affected versions of uv-tj-demo.
Mitigation strategies for CVE-2017-16200 should focus on implementing proper input validation and sanitization mechanisms within the application code. The most effective approach involves normalizing and validating all user-supplied input before using it in file system operations, ensuring that path traversal sequences are rejected or properly handled. Implementing a whitelist-based approach for file access, where only explicitly allowed paths are permitted, provides strong protection against such attacks. Additionally, organizations should consider implementing proper access controls and privilege separation, ensuring that the file server operates with minimal necessary permissions and does not have access to sensitive system directories. Regular security updates and patches should be applied to address known vulnerabilities, and application security testing should include thorough input validation testing to prevent similar issues from occurring in other components of the system.