CVE-2007-3407 in Simple HTTPD
Summary
by MITRE
Sergey Lyubka Simple HTTPD (shttpd) 1.38 allows remote attackers to obtain sensitive information (script source code) via a URL with a trailing encoded space (%20).
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Analysis
by VulDB Data Team • 02/22/2025
The vulnerability described in CVE-2007-3407 affects Sergey Lyubka Simple HTTPD version 1.38, a lightweight web server implementation designed for embedded systems and simple web serving requirements. This particular flaw represents a critical information disclosure vulnerability that enables remote attackers to access sensitive script source code through carefully crafted URL requests. The vulnerability arises from insufficient input validation and path handling within the web server's URL processing logic, specifically when dealing with encoded characters in file paths.
The technical flaw manifests when a remote attacker crafts a URL containing a trailing encoded space character represented as %20 in the request. This seemingly innocuous character sequence triggers a path traversal behavior within the shttpd server implementation where it fails to properly sanitize or validate the URL components before attempting to serve files. The server processes the encoded space as part of the file path without adequate boundary checking, allowing it to access files that should normally be restricted or protected from direct web access. This vulnerability falls under the category of improper input validation as defined by CWE-20, specifically involving the failure to properly handle special characters in file paths.
The operational impact of this vulnerability is significant for systems running the affected shttpd version, particularly those hosting sensitive web applications or scripts. Attackers can exploit this weakness to retrieve script source code, configuration files, and potentially other sensitive data that should remain protected from unauthorized access. The vulnerability is particularly concerning in embedded systems environments where shttpd is commonly deployed, as these systems often handle critical operations and may contain proprietary code or sensitive business logic within their web-accessible directories. The ability to obtain script source code provides attackers with valuable intelligence for further exploitation attempts, including identifying potential additional vulnerabilities, understanding application logic, and developing more sophisticated attack vectors.
This vulnerability aligns with several ATT&CK framework techniques including T1566.001 for Phishing with Malicious Links and T1083 for File and Directory Discovery, as it enables attackers to discover and retrieve sensitive files from the target system. The attack chain typically begins with reconnaissance through crafted URLs, followed by information gathering and potentially leading to more severe compromise scenarios. Organizations should consider this vulnerability as part of a broader security assessment, particularly in environments where embedded systems or lightweight web servers are deployed. The vulnerability demonstrates the importance of proper input sanitization and the need for robust path validation mechanisms in web server implementations.
Mitigation strategies for this vulnerability include immediate upgrade to a patched version of shttpd where the input validation has been properly addressed. System administrators should also implement network-level restrictions to limit access to sensitive directories and ensure that web server configurations properly restrict access to script files and other sensitive resources. Additionally, organizations should conduct thorough security reviews of all web server implementations, paying particular attention to how encoded characters and special sequences are handled within URL processing logic. Regular security audits and vulnerability assessments should be performed to identify similar issues in other web server implementations and ensure comprehensive protection against information disclosure attacks.