CVE-2017-16157 in censorify.tanisjr
Summary
by MITRE
censorify.tanisjr is a simple web server and API RESTful service. censorify.tanisjr 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-2017-16157 affects censorify.tanisjr, a web server and RESTful API service designed for content filtering operations. This application exposes a critical directory traversal flaw that allows malicious actors to access arbitrary files on the underlying filesystem through crafted URL requests. The vulnerability stems from inadequate input validation and path sanitization within the application's request handling mechanism, creating an exploitable condition that bypasses normal access controls and file system boundaries.
The technical implementation of this vulnerability resides in the application's failure to properly sanitize user-supplied input before processing file system requests. When a user submits a URL containing directory traversal sequences such as "../", the application processes these sequences without adequate validation, allowing the attacker to navigate beyond the intended directory structure and access files that should remain restricted. This flaw directly maps to CWE-22, which defines improper limitation of a pathname to a restricted directory, commonly known as path traversal or directory traversal vulnerabilities. The vulnerability exists at the application layer where user input is directly incorporated into file system operations without proper sanitization or normalization.
The operational impact of this vulnerability is severe and far-reaching, as it provides attackers with unrestricted access to the entire file system of the host machine running the censorify.tanisjr service. An attacker could potentially access sensitive configuration files, database credentials, application source code, user data, and system files that should remain protected. This access could lead to complete system compromise, data exfiltration, and persistence mechanisms being established. The vulnerability affects the confidentiality and integrity of the system, as unauthorized access to file system resources can result in data leakage, modification of critical application components, and potential privilege escalation opportunities. The attack surface is particularly concerning given that this is a web-facing service that likely operates with elevated privileges necessary for its filtering functions.
Mitigation strategies for this vulnerability should prioritize immediate implementation of input validation and sanitization measures. The primary defense involves normalizing all user-supplied paths through proper canonicalization and ensuring that any directory traversal sequences are rejected or properly resolved. Organizations should implement strict path validation that prevents access to parent directories and enforces proper access controls through the principle of least privilege. Additional security measures include deploying web application firewalls to detect and block suspicious path traversal patterns, implementing proper logging and monitoring to detect exploitation attempts, and ensuring that the application runs with minimal required privileges. This vulnerability aligns with ATT&CK technique T1083, which describes discovery of file and directory permissions, and T1566, which covers credential access through exploitation of remote services. Regular security assessments and code reviews should be conducted to prevent similar path traversal issues in other components of the application infrastructure.