CVE-2001-0971 in 4D Webserver
Summary
by MITRE
Directory traversal vulnerability in ACI 4d webserver allows remote attackers to read arbitrary files via a .. (dot dot) or drive letter (e.g., C:) in an HTTP request.
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Analysis
by VulDB Data Team • 05/25/2019
The vulnerability identified as CVE-2001-0971 represents a critical directory traversal flaw within the ACI 4d webserver implementation that fundamentally compromises the security boundaries of web applications. This weakness stems from inadequate input validation mechanisms that fail to properly sanitize user-supplied data in HTTP requests, allowing malicious actors to manipulate file path references through the use of directory traversal sequences such as .. or drive letter specifications like C:. The vulnerability operates at the core of web server file access controls, where legitimate application functionality becomes exploitable due to insufficient validation of user inputs that should be strictly controlled and sanitized before processing.
The technical exploitation of this vulnerability occurs when an attacker crafts HTTP requests containing directory traversal sequences that bypass normal file access restrictions. When the ACI 4d webserver processes these malformed requests, it fails to properly validate or sanitize the input paths, allowing the server to interpret and resolve the traversal sequences as legitimate file access commands. This enables attackers to navigate beyond the intended web root directory and access arbitrary files on the underlying file system. The vulnerability specifically affects the webserver's handling of file paths in HTTP requests, where the absence of proper path normalization and validation creates an opening for unauthorized file access. According to CWE standards, this corresponds 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 extends far beyond simple unauthorized file access, as it provides attackers with the capability to read sensitive system files, configuration data, application source code, and potentially credentials stored in files accessible through the web server. Attackers can leverage this vulnerability to extract database connection strings, application passwords, system configuration files, and other sensitive information that could facilitate further exploitation or lateral movement within the compromised environment. The vulnerability also creates opportunities for attackers to upload malicious files, modify existing web content, or even execute arbitrary code depending on the server configuration and file permissions. From an attacker's perspective, this vulnerability maps to several ATT&CK techniques including T1083 (File and Directory Discovery) and T1566 (Phishing), as it enables initial reconnaissance and privilege escalation activities.
Mitigation strategies for CVE-2001-0971 require immediate implementation of robust input validation and sanitization measures within the webserver configuration. Organizations should implement strict path validation that rejects any requests containing directory traversal sequences or drive letter specifications in file path parameters. The recommended approach involves normalizing all file paths through canonicalization processes that resolve relative paths to absolute paths while maintaining strict boundaries around the web root directory. Security measures should include configuring the webserver to reject requests containing .. sequences or drive letter references, implementing proper access controls that limit file system access to only necessary directories, and deploying web application firewalls that can detect and block such traversal attempts. Additionally, regular security audits should verify that all web applications and services properly validate user inputs and implement secure coding practices that prevent similar vulnerabilities from being introduced in future development cycles. The vulnerability highlights the critical importance of input validation and proper access controls as fundamental security measures that should be implemented at multiple layers of the system architecture.