CVE-2004-1887 in Imgsvr
Summary
by MITRE
Ada Image Server (ImgSvr) 0.4 allows remote attackers to view directories or download files via an HTTP request with a trailing %00 (null).
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Analysis
by VulDB Data Team • 08/20/2025
The vulnerability identified as CVE-2004-1887 affects the Ada Image Server version 0.4, a web server application designed to serve image files through HTTP protocols. This particular flaw represents a classic input validation issue that exploits how the server processes HTTP requests containing special characters. The vulnerability specifically manifests when a remote attacker crafts an HTTP request with a trailing null byte character represented as %00 in URL encoding. This seemingly innocuous character sequence can be appended to file paths or directory requests, allowing unauthorized access to resources that should remain protected. The vulnerability stems from inadequate sanitization of input parameters within the server's request handling mechanism, creating a path traversal condition that bypasses normal access controls.
The technical exploitation of this vulnerability relies on the server's failure to properly validate and sanitize URL parameters before processing file system requests. When the Ada Image Server receives an HTTP request containing a null byte character at the end of a file path or directory specification, the server's internal processing logic fails to properly terminate the string or validate the input. This allows the null byte to be interpreted as a legitimate end-of-string marker, potentially causing the server to interpret subsequent characters in the URL as part of the file path rather than as separate parameters or control sequences. The null byte essentially acts as a delimiter that the server does not properly handle, leading to unexpected behavior in file system operations. This type of vulnerability falls under the category of improper input validation as defined by CWE-20, which addresses weaknesses in input sanitization that can lead to various security issues including path traversal attacks.
The operational impact of this vulnerability extends beyond simple information disclosure, as it enables remote attackers to potentially access sensitive files or directories that should be protected from unauthorized access. Attackers can leverage this weakness to bypass authentication mechanisms and directly access files on the server's file system, potentially including configuration files, database files, or other sensitive data that could be used for further exploitation. The vulnerability allows for arbitrary file access and download capabilities, which could result in data breaches, system compromise, or the exposure of proprietary information. Additionally, since the attack can be executed remotely without requiring authentication, it represents a significant security risk that could be exploited by any internet-connected attacker. The severity is amplified by the fact that this vulnerability affects a web server application that may be running with elevated privileges, potentially allowing attackers to access system files or other resources that are normally protected.
Mitigation strategies for this vulnerability should focus on implementing proper input validation and sanitization within the Ada Image Server application. The most effective approach involves modifying the server's request handling code to properly validate and sanitize all URL parameters, specifically ensuring that null byte characters are either rejected or properly escaped before any file system operations are performed. This aligns with the principle of least privilege and input validation as recommended in the OWASP Top Ten security practices. Organizations should also consider implementing web application firewalls or security filters that can detect and block requests containing null byte sequences in file paths. The vulnerability demonstrates the critical importance of proper input validation in web applications and highlights the need for comprehensive security testing including penetration testing and code review processes. Additionally, system administrators should ensure that the Ada Image Server is kept up to date with the latest security patches and that unnecessary services are disabled to minimize the attack surface. This vulnerability serves as a reminder of the importance of proper string handling and input validation in preventing path traversal attacks, which are commonly classified under the ATT&CK framework's technique T1059.007 for command and scripting interpreter and T1566 for credential access through unauthorized access to system resources.