CVE-2017-16165 in calmquist.static-server
Summary
by MITRE
calmquist.static-server is a static file server. calmquist.static-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-2017-16165 affects calmquist.static-server, a lightweight static file server implementation that serves web content directly from the file system. This particular static server is designed to provide simple file serving capabilities without requiring complex web server configurations, making it popular for development environments and simple deployment scenarios. The vulnerability manifests as a directory traversal flaw that allows unauthorized access to the underlying file system through carefully crafted URL requests.
The technical flaw resides in the server's improper input validation and path handling mechanisms. When processing incoming HTTP requests, the application fails to adequately sanitize or normalize URL paths before resolving them against the file system. Attackers can exploit this weakness by including directory traversal sequences such as "../" within the requested file paths, effectively allowing them to navigate outside the intended document root directory and access arbitrary files on the server. This 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 operational impact of this vulnerability is significant as it provides attackers with unauthorized access to the entire file system hierarchy where the static server is running. An attacker could potentially access sensitive configuration files, source code repositories, user data, system credentials, and other confidential information stored on the same server. The severity escalates when considering that static servers often run with elevated privileges or have access to critical system resources, making the compromise of such applications particularly dangerous for organizations. This vulnerability enables attackers to perform reconnaissance activities, escalate privileges, or extract sensitive data without requiring authentication or complex exploitation techniques.
Mitigation strategies for this vulnerability include implementing proper input validation and path normalization within the application code to prevent directory traversal sequences from being processed. The server should sanitize all incoming URLs by removing or encoding special path characters such as "../", "..\", and similar traversal patterns. Organizations should also consider implementing proper access controls and privilege separation, ensuring that the static server runs with minimal required permissions. Additionally, deployment practices should include regular security assessments and updates to ensure that known vulnerabilities are addressed promptly. The remediation aligns with ATT&CK technique T1083, which covers directory and file permissions modification, and supports defensive measures outlined in the MITRE ATT&CK framework for preventing unauthorized access to system resources.