CVE-2017-16161 in shenliru
Summary
by MITRE
shenliru is a simple file server. shenliru is vulnerable to a directory traversal issue, giving an attacker access to the filesystem by placing "../" in the url.
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 02/16/2020
The shenliru file server vulnerability represents a critical directory traversal flaw that exposes systems to unauthorized file system access. This vulnerability stems from inadequate input validation within the web application's URL processing mechanism, allowing malicious actors to manipulate file paths through crafted requests containing ../ sequences. The flaw exists in the application's handling of user-supplied path parameters without proper sanitization or validation, creating an exploitable condition that bypasses normal file access controls.
This directory traversal vulnerability directly maps to CWE-22, which defines improper limitation of a pathname to a restricted directory, commonly known as path traversal or directory traversal. The attack vector leverages the fundamental weakness in how the application processes relative path references, enabling attackers to navigate outside the intended document root directory. When ../ sequences are injected into URLs, they instruct the server to move up one directory level in the file system hierarchy, potentially allowing access to sensitive system files, configuration data, or other restricted resources that should remain protected from external access.
The operational impact of this vulnerability extends beyond simple information disclosure, as it can lead to complete system compromise when combined with other attack vectors. An attacker exploiting this flaw can potentially access system configuration files, user credentials, application source code, or even execute arbitrary code if the server has appropriate permissions. The vulnerability affects any system running shenliru file server software and can be exploited remotely without requiring authentication, making it particularly dangerous in production environments where sensitive data may be exposed.
Mitigation strategies for this vulnerability should focus on implementing robust input validation and sanitization mechanisms. The primary defense involves rejecting or properly encoding any path traversal sequences in user-supplied input before processing. Organizations should implement strict path validation that ensures all requested paths remain within the designated document root directory. Additionally, deploying web application firewalls and implementing proper access controls can provide additional layers of protection. The solution aligns with ATT&CK technique T1083, which covers the discovery of file and directory permissions, and T1566, which covers credential harvesting through various attack vectors. Regular security updates and code reviews should be implemented to prevent similar vulnerabilities from emerging in future releases of the software.