CVE-2017-16163 in dylmomo
Summary
by MITRE
dylmomo is a simple file server. dylmomo 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 CVE-2017-16163 vulnerability affects dylmomo, a simple file server implementation that suffers from a critical directory traversal flaw. This vulnerability stems from inadequate input validation within the application's URL processing mechanism, allowing remote attackers to access arbitrary files on the server's filesystem through maliciously crafted requests. The flaw specifically manifests when the application fails to properly sanitize user-supplied URL parameters, enabling attackers to navigate beyond the intended directory structure using directory traversal sequences such as "../". This vulnerability represents a classic path traversal issue that has been documented in numerous security frameworks and standards.
The technical exploitation of this vulnerability occurs when an attacker crafts a URL containing directory traversal sequences that bypass the application's intended file access controls. The dylmomo server processes these malformed paths without proper validation, allowing the attacker to access files outside the designated web root directory. This can lead to unauthorized access to sensitive system files, configuration data, application source code, and potentially user credentials stored on the server. 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. This weakness enables attackers to manipulate file access requests and gain access to resources they should not be permitted to access.
The operational impact of this vulnerability extends beyond simple information disclosure, as it can potentially lead to complete system compromise. An attacker who successfully exploits this vulnerability can access critical system files including password hashes, database connection strings, and application configuration files that may contain sensitive credentials. The vulnerability also enables potential privilege escalation attacks if the application runs with elevated privileges, as attackers can potentially access system files that are normally restricted. This weakness creates a significant attack surface that aligns with ATT&CK technique T1083, which covers File and Directory Discovery, and T1078, which covers Valid Accounts, as the vulnerability can be leveraged to gather information about the system and potentially escalate privileges.
Mitigation strategies for CVE-2017-16163 should focus on implementing proper input validation and sanitization mechanisms within the dylmomo application. The most effective approach involves implementing strict path validation that rejects any URL parameters containing directory traversal sequences such as "../" or "..\". Additionally, developers should implement a whitelist-based approach to file access, ensuring that only explicitly allowed file paths can be accessed through the application. The application should also employ proper authentication and authorization mechanisms to limit access to sensitive files even if path traversal attacks are attempted. Security patches should be applied immediately to address this vulnerability, as the flaw allows for complete file system access and can be exploited without any special privileges. Organizations should also consider implementing web application firewalls that can detect and block suspicious path traversal patterns in real-time, providing an additional layer of protection against exploitation attempts.