CVE-2017-16085 in tinyserver2
Summary
by MITRE
tinyserver2 is a webserver for static files. tinyserver2 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 • 02/15/2020
The vulnerability identified as CVE-2017-16085 affects tinyserver2, a lightweight web server designed for serving static files. This particular issue represents a classic directory traversal flaw that fundamentally compromises the server's file system security boundaries. The vulnerability arises from insufficient input validation within the URL parsing mechanism, allowing malicious actors to exploit the server's file handling capabilities through crafted requests containing directory traversal sequences.
The technical flaw manifests when the web server processes URL requests containing "../" sequences that are intended to navigate up directory levels. This weakness stems from the server's failure to properly sanitize or validate path components before resolving file requests, creating an opportunity for attackers to access files outside the designated web root directory. The vulnerability directly maps to CWE-22, which describes improper limitation of a pathname to a restricted directory, commonly known as directory traversal or path traversal attacks. This type of vulnerability is particularly dangerous because it can potentially expose sensitive system files, configuration data, or user information stored on the server.
The operational impact of this vulnerability extends beyond simple information disclosure, as it can enable attackers to gain unauthorized access to the underlying file system. An attacker could potentially access system configuration files, user data, application source code, or other sensitive resources that should remain isolated from web access. The consequences become more severe when considering that tinyserver2 is designed for static file serving, meaning it likely has access to a wide range of files that could contain confidential information or serve as entry points for further attacks. This vulnerability essentially removes the server's built-in security boundaries, allowing arbitrary file access that could lead to complete system compromise or data breaches.
Mitigation strategies for CVE-2017-16085 should focus on implementing proper input validation and sanitization mechanisms within the web server's URL handling code. The most effective approach involves normalizing all file paths and ensuring that directory traversal sequences are properly rejected or neutralized before any file system operations occur. Security measures should include implementing strict path validation that prevents access to parent directories and ensuring that all file requests are confined to the designated web root. Additionally, organizations should consider implementing web application firewalls or security controls that can detect and block suspicious URL patterns containing traversal sequences. From an ATT&CK framework perspective, this vulnerability aligns with techniques such as T1083 (File and Directory Discovery) and T1566 (Phishing with Malicious Attachments) where attackers might use directory traversal to access sensitive files that could then be used for further exploitation or data exfiltration.