CVE-2017-16213 in mfrserver
Summary
by MITRE
mfrserver is a simple file server. mfrserver 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-2017-16213 affects mfrserver, a lightweight file server implementation that serves files over HTTP protocols. This directory traversal vulnerability represents a critical security flaw that allows remote attackers to access arbitrary files on the server's filesystem by manipulating URL parameters. The flaw specifically manifests when the application fails to properly sanitize user input containing directory traversal sequences, enabling unauthorized access to sensitive system resources.
The technical root cause of this vulnerability aligns with CWE-22, which describes improper limitation of a pathname to a restricted directory, commonly known as path traversal or directory traversal attacks. When mfrserver processes incoming requests, it does not adequately validate or sanitize the URL path components, allowing attackers to inject sequences like "../" that navigate up the directory hierarchy. This weakness enables attackers to traverse beyond the intended serving directory and access files that should remain protected, potentially exposing system configuration files, user data, or even system binaries.
From an operational perspective, this vulnerability poses significant risks to organizations using mfrserver as part of their infrastructure. Attackers can leverage this flaw to access sensitive information such as configuration files containing database credentials, user authentication details, or system-level files that could provide further attack vectors. The impact extends beyond simple data exposure since the attacker could potentially access files that contain system information, application source code, or other sensitive artifacts that could aid in more sophisticated attacks. The vulnerability is particularly dangerous because it requires no authentication and can be exploited through simple HTTP requests.
The attack surface for this vulnerability is broad as it affects any system running mfrserver that does not properly implement input validation. The flaw is classified under the MITRE ATT&CK framework as part of the T1083 technique for discovering system information, where attackers can use directory traversal to enumerate the file system structure and identify valuable targets. Organizations should implement immediate mitigations including input validation and sanitization of all URL parameters, implementing proper path normalization, and restricting file server access to trusted networks only. Additionally, deploying web application firewalls and implementing proper access controls can help prevent exploitation of this vulnerability. Regular security updates and patches should be applied to ensure the server software remains protected against known vulnerabilities.