CVE-2017-16210 in jn_jj_server
Summary
by MITRE
jn_jj_server is a static file server. jn_jj_server 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-2017-16210 affects jn_jj_server, a static file server implementation that suffers from a critical directory traversal flaw. This vulnerability stems from inadequate input validation and path handling within the server's file access mechanisms, allowing remote attackers to manipulate file paths through URL parameters. The specific flaw enables attackers to navigate beyond the intended document root directory by exploiting the use of "../" sequences in Uniform Resource Locators. This type of vulnerability falls under the category of improper input validation and is classified as CWE-22, which represents improper limitation of a pathname to a restricted directory, commonly known as path traversal or directory traversal. The issue represents a fundamental security weakness in how the server processes file requests, where user-supplied input directly influences the file system access paths without proper sanitization or validation.
The operational impact of this vulnerability is severe and far-reaching, as it provides attackers with unrestricted access to the underlying file system of the server. An attacker can leverage this flaw to read arbitrary files, potentially accessing sensitive configuration files, authentication credentials, application source code, or other confidential data stored on the system. The vulnerability extends beyond simple file reading capabilities, as it may also enable attackers to execute malicious code or perform destructive operations depending on the server's configuration and the permissions of the running process. This type of vulnerability directly violates the principle of least privilege and can lead to complete system compromise when combined with other attack vectors. The attack surface is particularly concerning because the vulnerability can be exploited through simple HTTP requests, making it accessible to attackers with minimal technical expertise and no authentication requirements.
Mitigation strategies for CVE-2017-16210 must address both the immediate vulnerability and establish robust defensive measures to prevent similar issues. The primary fix involves implementing proper input validation and sanitization of all user-supplied paths before they are processed by the file server. This includes rejecting or normalizing path sequences containing "../" or similar traversal patterns, as well as implementing strict path resolution mechanisms that ensure all file access operations remain within designated directories. Organizations should also implement proper access controls and privilege separation to limit the impact of any potential exploitation. The vulnerability aligns with several ATT&CK techniques including T1083 (File and Directory Discovery) and T1566 (Phishing with Malicious Attachments) as attackers can use directory traversal to discover and access sensitive files. Additionally, this vulnerability demonstrates the importance of following secure coding practices and adhering to the principle of least privilege in system design, as recommended by various cybersecurity frameworks and standards including ISO/IEC 27001 and NIST cybersecurity guidelines. Regular security testing including penetration testing and code reviews should be implemented to identify and remediate similar vulnerabilities before they can be exploited by malicious actors.