CVE-2017-16158 in dcserver
Summary
by MITRE
dcserver is a static file server. dcserver 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-2017-16158 affects dcserver, 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 "../" sequences. The vulnerability represents a fundamental failure in input validation and path resolution mechanisms within the server's file access routines.
This directory traversal vulnerability stems from inadequate sanitization of user-supplied input in the URL parsing logic. When dcserver processes requests containing "../" sequences in the URL path, it fails to properly validate or normalize these paths before attempting to serve files from the filesystem. The flaw enables attackers to navigate beyond the intended document root directory and access sensitive files that should remain protected. This issue directly maps to CWE-22, which describes improper limitation of a pathname to a restricted directory, commonly known as path traversal or directory traversal attacks.
The operational impact of this vulnerability is severe and multifaceted. An attacker exploiting this weakness can potentially access configuration files, source code, database files, user credentials, and other sensitive data stored on the server. The vulnerability allows for arbitrary file reading across the entire filesystem, which can lead to complete system compromise. Depending on the server configuration and file permissions, attackers might gain access to system binaries, application logs, and potentially escalate privileges through the exposure of sensitive information. This type of vulnerability aligns with ATT&CK technique T1083, which covers discovering file and directory permissions on compromised systems.
Mitigation strategies for this vulnerability should include immediate patching of the dcserver application to implement proper input validation and path normalization. The server should enforce strict path validation that rejects or removes any "../" sequences from user-supplied paths before file access operations are performed. Additionally, implementing proper access controls through the use of chroot jails, restricted file access permissions, and principle of least privilege configurations can significantly reduce the impact of such vulnerabilities. Organizations should also consider implementing web application firewalls and input validation rules that specifically target directory traversal patterns to provide additional defense in depth measures. Regular security assessments and code reviews focusing on input validation and path handling routines are essential to prevent similar vulnerabilities from emerging in other applications within the infrastructure.