CVE-2017-16216 in tencent-server
Summary
by MITRE
tencent-server is a simple web server. tencent-server 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-2017-16216 affects tencent-server, a simple web server implementation that suffers from a critical directory traversal flaw. This vulnerability allows remote attackers to access arbitrary files on the server's filesystem by manipulating URL parameters through the strategic insertion of "../" sequences. The flaw represents a fundamental security weakness in how the server processes file paths and handles user input, creating an avenue for unauthorized data access that can potentially expose sensitive system information, configuration files, or user data.
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 technical implementation flaw occurs when the web server fails to properly sanitize or validate input parameters that contain file path references, allowing attackers to manipulate the intended file access path through relative path components. The vulnerability exists at the application layer where user-supplied data is directly incorporated into file system operations without adequate validation or sanitization mechanisms.
The operational impact of this vulnerability extends beyond simple data theft, as it can enable attackers to gain unauthorized access to critical system resources. An attacker exploiting this vulnerability could potentially read system configuration files, access database files, retrieve source code repositories, or even obtain sensitive credentials stored in configuration files. The attack vector is particularly concerning because it requires minimal effort to exploit, typically involving only URL manipulation, making it accessible to attackers with basic technical knowledge. This vulnerability can also serve as a stepping stone for more sophisticated attacks, potentially enabling privilege escalation or further system compromise through the acquisition of additional system information.
Mitigation strategies for CVE-2017-16216 should focus on implementing proper input validation and sanitization mechanisms to prevent directory traversal attacks. Organizations should ensure that all user-supplied input containing file path references undergoes rigorous validation to prevent the inclusion of directory traversal sequences such as "../" or "..\". The implementation of secure coding practices including the use of allowlists for acceptable file paths, proper path normalization, and the enforcement of strict file access controls can effectively prevent exploitation. Additionally, deploying web application firewalls and implementing proper access controls can provide additional layers of defense. From an ATT&CK framework perspective, this vulnerability aligns with techniques such as T1083 (File and Directory Discovery) and T1566 (Phishing with Malicious Attachment) where attackers may use directory traversal to gather intelligence about the target system. Regular security assessments and code reviews should be conducted to identify and remediate similar vulnerabilities in web server implementations, ensuring that all file access operations properly validate and sanitize input parameters to prevent unauthorized system resource access.