CVE-2017-16122 in cuciuci
Summary
by MITRE
cuciuci is a simple fileserver. cuciuci 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 cuciuci fileserver vulnerability CVE-2017-16122 represents a critical directory traversal flaw that exposes systems to unauthorized file system access. This vulnerability specifically affects the cuciuci simple fileserver implementation, which is designed to serve files over HTTP protocols. The flaw stems from inadequate input validation and path sanitization within the application's URL handling mechanism, allowing malicious actors to manipulate file paths through crafted requests containing directory traversal sequences.
The technical exploitation of this vulnerability relies on the manipulation of URL parameters to navigate beyond the intended directory boundaries. Attackers can construct malicious URLs containing "../" sequences that bypass normal access controls and gain access to files and directories outside the designated serving path. This type of vulnerability falls under the Common Weakness Enumeration category CWE-22, which specifically addresses improper limitation of a pathname to a restricted directory, commonly known as path traversal or directory traversal attacks. The flaw demonstrates a fundamental lack of input validation and proper path resolution within the fileserver's processing pipeline.
The operational impact of CVE-2017-16122 extends beyond simple unauthorized file access, potentially enabling attackers to read sensitive system files, configuration data, or user information stored on the affected server. Depending on the server configuration and file permissions, successful exploitation could lead to complete system compromise, data exfiltration, or further lateral movement within network environments. The vulnerability aligns with ATT&CK technique T1083 (File and Directory Discovery) and T1566 (Phishing for Information) as attackers can systematically enumerate and access sensitive files without authentication. This weakness particularly affects systems where the fileserver operates with elevated privileges or where sensitive data is stored in accessible locations.
Mitigation strategies for this vulnerability require immediate implementation of proper input validation and path sanitization measures within the cuciuci fileserver application. Organizations should enforce strict path validation that rejects or removes directory traversal sequences from URL parameters before processing file requests. The implementation of a whitelist-based approach for acceptable file paths, combined with proper access controls and privilege separation, significantly reduces exploitation risk. Additionally, deploying web application firewalls and implementing security headers can provide additional layers of protection. Regular security auditing and input validation testing should be conducted to prevent similar vulnerabilities from emerging in future versions of the software, aligning with industry best practices for secure coding and application security hardening.