CVE-2017-16154 in earlybird
Summary
by MITRE
earlybird is a web server module for early development. earlybird 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-2017-16154 vulnerability affects the earlybird web server module, which is designed for early development purposes but has found deployment in production environments despite its experimental nature. This module suffers from a critical directory traversal flaw that allows remote attackers to access arbitrary files on the underlying filesystem through crafted URL requests. The vulnerability stems from inadequate input validation and path sanitization within the module's request handling logic, where user-supplied URL parameters are directly processed without proper normalization or restriction mechanisms. This issue represents a fundamental security weakness in the module's architecture that could be exploited by malicious actors to gain unauthorized access to sensitive system resources.
The technical implementation of this vulnerability manifests through the improper handling of relative path references in HTTP requests. When an attacker submits a URL containing "../" sequences, the earlybird module fails to properly sanitize or validate these path traversal attempts, allowing the application to resolve these references relative to the web root directory. This creates an opportunity for attackers to navigate upward through the directory structure and access files that should remain protected, including configuration files, source code, log files, and potentially sensitive data stored on the server. The vulnerability operates at the application layer and can be exploited through simple HTTP GET requests without requiring authentication or special privileges.
The operational impact of this vulnerability extends beyond simple information disclosure, as it provides attackers with the ability to access the complete filesystem hierarchy of the affected server. Depending on the server configuration and file permissions, attackers may be able to retrieve sensitive configuration files containing database credentials, API keys, or other authentication tokens. The vulnerability also enables potential further exploitation through access to application source code, which could reveal additional attack vectors or provide insights into the system architecture. This type of vulnerability directly violates the principle of least privilege and can lead to complete system compromise if sensitive files are accessible through the traversal mechanism.
Mitigation strategies for CVE-2017-16154 should focus on immediate input validation and path normalization within the earlybird module. The most effective approach involves implementing strict path validation that rejects any URL components containing directory traversal sequences such as "../" or "..\". This aligns with CWE-22, which categorizes path traversal vulnerabilities as a critical security weakness requiring proper input sanitization. Organizations should also consider implementing a whitelist-based approach for file access, where only predefined directories and file types are permitted for access. Additionally, the module should be updated to properly normalize all file paths before processing, ensuring that any attempt to traverse directories is detected and blocked. The ATT&CK framework categorizes this type of vulnerability under T1083, File and Directory Discovery, as it enables adversaries to enumerate and access system files. Regular security audits and input validation testing should be implemented to prevent similar issues in other modules and applications within the system.