CVE-2017-16219 in yttivy
Summary
by MITRE
yttivy is a static file server. yttivy 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-2017-16219 affects yttivy, a static file server implementation that suffers from a critical directory traversal flaw. This security weakness allows malicious actors 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 handling within the application's file serving mechanism.
The technical root cause of this issue stems from improper sanitization of user-supplied input in URL paths. When yttivy processes incoming requests, it fails to adequately validate or sanitize the requested file paths before attempting to serve files from the filesystem. This omission creates an opportunity for attackers to craft malicious URLs that traverse directory structures beyond the intended document root. The vulnerability 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. Such flaws typically arise when applications fail to properly canonicalize or validate file paths before accessing them.
The operational impact of this vulnerability is severe and potentially catastrophic for systems running affected versions of yttivy. An attacker could exploit this weakness to access sensitive files including configuration files, source code repositories, database files, system credentials, and other confidential data that should remain protected. The attack surface extends beyond simple file access to potentially enable further exploitation such as remote code execution through the retrieval of executable scripts or the discovery of additional system vulnerabilities. This type of attack aligns with ATT&CK technique T1083, which covers discovering file and directory permissions, and T1566, which involves credential access through various means including file system exploration.
Mitigation strategies for this vulnerability should focus on immediate implementation of proper input validation and path normalization. System administrators should ensure that all user-supplied paths are strictly validated against a whitelist of allowed directories and that any path traversal attempts are immediately rejected. The application should implement proper path canonicalization to prevent double dots and forward slashes from creating unintended directory traversal. Additionally, deploying web application firewalls and implementing proper access controls can provide additional layers of defense. Organizations should also consider upgrading to patched versions of yttivy if available, and conducting comprehensive audits of their file serving applications to identify similar vulnerabilities. Regular security testing including penetration testing and static code analysis should be implemented to prevent similar issues in future development cycles. The vulnerability highlights the critical importance of input validation and proper access control mechanisms in web applications, particularly those handling file system operations.