CVE-2017-16110 in weather.swlyons
Summary
by MITRE
weather.swlyons is a simple web server for weather updates. weather.swlyons 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 • 02/15/2020
The vulnerability identified as CVE-2017-16110 affects weather.swlyons, a lightweight web server designed for delivering weather update information. This application falls under the category of embedded web servers commonly used in IoT devices and simple network services where minimal resource consumption is prioritized over comprehensive security features. The flaw represents a critical security weakness that undermines the fundamental principle of access control within web applications.
The technical implementation of this vulnerability stems from inadequate input validation within the web server's URL parsing mechanism. When users submit requests containing directory traversal sequences such as "../", the application fails to properly sanitize or validate these inputs before processing file system operations. This allows attackers to manipulate the path resolution logic and navigate outside the intended web root directory. 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. The flaw operates at the application layer where user-supplied data is processed without adequate sanitization, creating an exploitable condition that can be leveraged by malicious actors.
The operational impact of this vulnerability extends beyond simple information disclosure, as it provides attackers with unrestricted access to the underlying file system of the server. An attacker can potentially access sensitive configuration files, authentication credentials, application source code, and other system resources that should remain protected. This access could enable further exploitation activities including privilege escalation, data exfiltration, or even system compromise. The vulnerability particularly affects environments where weather.swlyons operates in restricted network zones or where the server hosts sensitive data, making it a significant concern for organizations deploying such services. From an adversarial perspective, this vulnerability aligns with ATT&CK technique T1083, which involves discovering system information through directory listing and file access methods.
Mitigation strategies for this vulnerability must address the core issue of input validation and path normalization. Organizations should implement proper input sanitization routines that reject or filter out directory traversal sequences before processing user requests. The web server should enforce strict path validation that ensures all file operations occur within predetermined directories, effectively implementing a whitelist approach to file access. Additionally, deploying web application firewalls and implementing proper access controls can provide additional defense layers. Regular security audits and code reviews should be conducted to identify similar vulnerabilities in other components of the system. The remediation process should also include updating the application to a version that properly handles user input or implementing proper path resolution mechanisms that prevent arbitrary file system access through URL manipulation.