CVE-2007-6405 in HTTPD
Summary
by MITRE
Sergey Lyubka Simple HTTPD (shttpd) 1.38 and earlier on Windows allows remote attackers to download arbitrary CGI programs or scripts via a URI with an appended (1) + character, (2) . character, (3) %2e sequence (hex-encoded dot), or (4) hex-encoded character greater than 0x7f. NOTE: the %20 vector is already covered by CVE-2007-3407.
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Analysis
by VulDB Data Team • 10/12/2024
The vulnerability identified as CVE-2007-6405 affects Sergey Lyubka's Simple HTTPD (shttpd) version 1.38 and earlier implementations running on Windows systems. This represents a directory traversal attack vector that enables remote attackers to bypass normal file access restrictions and retrieve arbitrary CGI programs or scripts from the server filesystem. The flaw stems from inadequate input validation within the URI parsing mechanism, specifically how the software handles special character sequences that should be interpreted as path separators or directory navigation indicators.
The technical implementation of this vulnerability exploits multiple encoding methods that allow attackers to manipulate URI parsing behavior. The attack vectors include appending a plus character, a dot character, a hex-encoded dot sequence %2e, or hex-encoded characters exceeding 0x7f. These methods work because the shttpd software fails to properly normalize or validate URI components before processing file requests, creating opportunities for attackers to traverse directory structures and access files outside of intended directories. The vulnerability specifically targets the Windows implementation where path resolution differs from Unix-like systems, making the exploitation more straightforward.
Operationally, this vulnerability poses significant risks to web server security as it allows attackers to download potentially sensitive CGI scripts or programs that may contain executable code, configuration information, or other system-related data. The impact extends beyond simple information disclosure to potential code execution if the downloaded CGI scripts contain malicious payloads or if they are executed by the web server. This vulnerability is particularly dangerous in environments where CGI scripts are used for dynamic content generation or administrative functions, as attackers could potentially gain access to privileged scripts or configuration files that control server operations.
Security mitigations for this vulnerability include immediate upgrading to shttpd version 1.39 or later, which contains proper input validation and URI normalization mechanisms. System administrators should also implement proper access controls and file permissions to limit what files can be accessed through CGI interfaces. Network-level protections such as web application firewalls and intrusion detection systems can help detect and block exploitation attempts. Organizations should conduct thorough security assessments of their web server configurations and implement proper input validation at all levels of their applications. This vulnerability aligns with CWE-22 Directory Traversal and follows patterns commonly associated with ATT&CK technique T1213.002 Accessing Data via File Transfer Protocol, where adversaries exploit improper input handling to access restricted files and potentially gain unauthorized access to system resources.