CVE-2017-16201 in zjjserver
Summary
by MITRE
zjjserver is a static file server. zjjserver is vulnerable to a directory traversal issue, giving an attacker access to the filesystem by placing "../" in the url.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 02/16/2020
The vulnerability identified as CVE-2017-16201 affects zjjserver, a static file server implementation that suffers from a critical directory traversal flaw. This security weakness allows remote attackers to access arbitrary files on the server's filesystem by manipulating URL parameters through the strategic insertion of directory traversal sequences such as "../". The vulnerability stems from inadequate input validation and sanitization within the server's path handling mechanisms, creating an exploitable condition that bypasses normal access controls. Such a flaw represents a fundamental breakdown in the server's security architecture, as it enables unauthorized information disclosure and potential system compromise through simple URL manipulation techniques.
The technical exploitation of this vulnerability occurs when the server fails to properly validate or sanitize user-supplied input that is used to construct file paths. When an attacker crafts a malicious URL containing sequences like "../", the server processes these traversal characters without proper validation, allowing access to files outside the intended document root directory. This type of 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. The flaw essentially allows attackers to navigate the filesystem hierarchy beyond the designated boundaries, potentially accessing sensitive configuration files, system binaries, or other confidential data that should remain protected from unauthorized access.
The operational impact of CVE-2017-16201 extends beyond simple information disclosure, as it provides attackers with the capability to potentially execute arbitrary code or gain deeper system access. An attacker could leverage this vulnerability to access system configuration files, database credentials, application source code, or other sensitive resources stored on the server. The implications are particularly severe for servers hosting sensitive data or serving as part of larger enterprise infrastructures, as this vulnerability could serve as an initial foothold for more extensive attacks. The vulnerability aligns with ATT&CK technique T1083, which covers discovering file and directory permissions, and T1005, which covers data from local system, as attackers can systematically explore the filesystem to identify valuable targets. Additionally, this vulnerability could enable further exploitation pathways such as privilege escalation or lateral movement within the network.
Mitigation strategies for CVE-2017-16201 should focus on implementing robust input validation and sanitization measures within the server's path handling logic. The most effective approach involves implementing strict path validation that rejects or removes directory traversal sequences from user input before processing file requests. Organizations should implement proper input filtering that strips or encodes potentially dangerous characters such as "../", "..\", and similar traversal patterns. Additionally, the server should be configured to operate within a restricted environment where file access is properly sandboxed, and access controls should be implemented to ensure that even if traversal occurs, the attacker cannot access critical system resources. System administrators should also consider implementing web application firewalls that can detect and block such traversal attempts, and regular security audits should be conducted to ensure that all file access mechanisms properly validate input. The vulnerability highlights the importance of following secure coding practices and implementing defense-in-depth strategies that prevent path traversal attacks through multiple layers of security controls.