CVE-2017-16199 in susu-sum
Summary
by MITRE
susu-sum is a static file server. susu-sum 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-2017-16199 affects susu-sum, a static file server implementation that fails to properly validate user-supplied input when processing file paths. This directory traversal flaw represents a critical security weakness that allows remote attackers to access arbitrary files on the server's filesystem by manipulating URL parameters through the use of directory traversal sequences such as "../". The vulnerability stems from insufficient input sanitization and path validation mechanisms within the application's file serving logic, enabling attackers to bypass normal access controls and potentially gain unauthorized access to sensitive system files, configuration data, or other protected resources.
This security flaw maps directly to CWE-22, which describes improper limitation of a pathname to a restricted directory, commonly known as path traversal or directory traversal attacks. The vulnerability operates at the application layer and can be exploited through HTTP requests that manipulate the file path parameter in the URL. Attackers can leverage this weakness to navigate upward through the directory structure and access files outside the intended web root directory, potentially leading to information disclosure, system compromise, or further attack vector exploitation. The attack requires minimal privileges and can be executed remotely, making it particularly dangerous in production environments where sensitive data may be exposed.
The operational impact of this vulnerability extends beyond simple information disclosure, as it can enable attackers to access critical system files, application configuration, database credentials, or other sensitive materials that may be stored on the same filesystem. Depending on the server configuration and the files accessible through the traversal, this vulnerability could lead to complete system compromise, data exfiltration, or the ability to execute arbitrary code if the attacker can access system binaries or scripts. The vulnerability affects any system running susu-sum where the directory traversal is not properly mitigated, potentially exposing organizations to significant risk.
Mitigation strategies for this vulnerability should focus on implementing proper input validation and sanitization mechanisms within the application. Organizations should ensure that all user-supplied input is rigorously validated and that path traversal sequences are explicitly blocked or removed from file path requests. Implementing a whitelist-based approach for file access, where only predetermined directories and file types are allowed, provides strong protection against such attacks. Additionally, deploying web application firewalls and implementing proper access controls can help prevent exploitation attempts. Regular security testing, including penetration testing and vulnerability scanning, should be conducted to identify and remediate similar weaknesses in the application's architecture. The fix typically involves modifying the application code to properly canonicalize and validate file paths before processing user requests, ensuring that directory traversal sequences are rejected or neutralized before any file operations occur.