CVE-2017-16149 in zwserver
Summary
by MITRE
zwserver is a weather web server. zwserver is vulnerable to a directory traversal issue, giving an attacker access to the filesystem by placing "../" in the url.
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 02/16/2020
The vulnerability identified as CVE-2017-16149 affects zwserver, a weather web server application that serves meteorological data through a web interface. This particular weakness represents a classic directory traversal vulnerability that allows unauthorized users to access files and directories outside the intended web root directory. The flaw manifests when the application fails to properly validate user-supplied input in URL parameters, enabling attackers to manipulate file paths through the use of directory traversal sequences such as "../". This vulnerability falls under the Common Weakness Enumeration category CWE-22, which specifically addresses improper limitation of a pathname to a restricted directory, commonly known as path traversal or directory traversal attacks.
The technical exploitation of this vulnerability occurs when an attacker crafts malicious URLs containing the "../" sequence to navigate upward through the directory structure of the web server. This allows the attacker to access sensitive files that should normally be restricted, including configuration files, system files, log files, and potentially even source code or database files. The impact extends beyond simple information disclosure as it can provide attackers with the ability to read arbitrary files on the server, potentially leading to further compromise through the exposure of system credentials, application secrets, or other sensitive data. The vulnerability is particularly concerning because it affects a web server application that likely handles user requests and data, making it a prime target for reconnaissance and privilege escalation activities.
From an operational perspective, this directory traversal vulnerability creates significant risks for organizations deploying zwserver applications, as it can lead to complete system compromise if sensitive files containing authentication credentials, database connection strings, or system configurations are accessible through the traversal attack. The attack vector is straightforward and requires minimal technical expertise to execute, making it particularly dangerous in environments where the application may be exposed to untrusted users or external networks. Security teams should note that this vulnerability aligns with ATT&CK technique T1083, which covers the discovery of files and directories, and T1566, which covers credential access through various means including file system access. The vulnerability can also potentially facilitate subsequent attacks such as command execution if the attacker can access files containing database credentials or application configuration that might allow for further exploitation.
The recommended mitigations for this vulnerability include implementing proper input validation and sanitization for all user-supplied parameters, particularly those used in file path construction. Applications should employ whitelisting approaches for file access, validate file paths against a known set of allowed directories, and ensure that all user input is properly encoded or escaped before being used in file system operations. Additionally, implementing proper access controls and privilege separation can limit the damage that could occur if such vulnerabilities are exploited. Organizations should also consider deploying web application firewalls that can detect and block directory traversal attempts, and ensure that zwserver applications are not running with elevated privileges that could amplify the impact of such an attack. Regular security assessments and code reviews should be conducted to identify similar vulnerabilities in other applications and to ensure that proper security controls are in place to prevent unauthorized file access.