CVE-2017-16162 in 22lixian
Summary
by MITRE
22lixian is a simple file server. 22lixian 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-2017-16162 affects 22lixian, a simple file server implementation that suffers from a critical directory traversal flaw. This vulnerability allows malicious actors to access arbitrary files on the underlying filesystem by manipulating URL parameters through the strategic insertion of "../" sequences. The flaw represents a fundamental security weakness in how the application processes file paths and handles user input, creating an unauthorized access vector that can potentially expose sensitive system data.
This directory traversal vulnerability falls under the Common Weakness Enumeration category CWE-22, which specifically addresses "Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')". The weakness occurs when an application fails to properly validate or sanitize user-supplied input that is used to construct file paths, allowing attackers to navigate outside the intended directory structure. The attack vector is particularly dangerous because it requires minimal effort from the attacker, who only needs to manipulate URL parameters to gain access to files that should remain protected.
The operational impact of this vulnerability extends beyond simple information disclosure, as it can enable attackers to access system configuration files, application source code, user data, and potentially sensitive credentials stored on the server. An attacker exploiting this vulnerability could retrieve database connection strings, application secrets, user authentication tokens, and other confidential information that could lead to further system compromise. The simplicity of the attack means that even basic automated scanning tools could identify and exploit this weakness, making it particularly dangerous in environments where such servers are publicly accessible.
Mitigation strategies for this vulnerability should focus on implementing proper input validation and sanitization mechanisms. The most effective approach involves implementing strict path validation that prevents any occurrence of "../" sequences or similar traversal patterns in file path construction. Additionally, applications should utilize secure coding practices such as maintaining a whitelist of allowed directories and files, implementing proper access controls, and using sandboxed execution environments. Organizations should also consider implementing web application firewalls to detect and block suspicious path traversal attempts. The remediation process requires thorough code review to identify all instances where user input is used to construct file paths, ensuring that proper sanitization occurs before any file system operations are performed. This vulnerability highlights the critical importance of input validation and proper access control mechanisms in preventing unauthorized system access.