CVE-2002-2256 in Webserver
Summary
by MITRE
Directory traversal vulnerability in pWins Webserver 0.2.5 and earlier allows remote attackers to read arbitrary files via Unicode characters.
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Analysis
by VulDB Data Team • 05/23/2019
The vulnerability described in CVE-2002-2256 represents a critical directory traversal flaw within the pWins Webserver version 0.2.5 and earlier releases. This security weakness stems from inadequate input validation mechanisms that fail to properly sanitize Unicode characters in file path requests. The vulnerability allows remote attackers to bypass normal access controls and retrieve arbitrary files from the web server's file system, potentially exposing sensitive information including configuration files, user data, and system resources. The issue manifests when the web server processes requests containing Unicode sequences that are not properly normalized or filtered during path resolution operations, creating an opportunity for attackers to manipulate file access patterns through carefully crafted requests.
The technical implementation of this vulnerability operates through the manipulation of Unicode character encoding sequences that can be interpreted differently by the web server's file system access routines. When a request containing Unicode characters is processed, the server's path resolution logic fails to properly normalize these sequences, allowing attackers to construct malicious paths that traverse directory structures beyond the intended web root. This weakness specifically exploits the server's failure to implement proper path canonicalization and validation, enabling attackers to access files that should remain protected. The vulnerability falls under CWE-22, which categorizes directory traversal or path traversal flaws, and represents a classic example of insufficient input sanitization in web applications. Attackers can leverage this weakness to access sensitive files such as password databases, configuration files, and system logs that may contain credentials or other valuable information.
The operational impact of CVE-2002-2256 extends beyond simple information disclosure to potentially enable more severe attacks including system compromise and data exfiltration. Remote attackers can systematically explore the file system structure to identify and access critical system resources, user accounts, and application data. The vulnerability's remote exploitability means that attackers do not require physical access to the system or local network presence to exploit the weakness, making it particularly dangerous in publicly accessible web environments. This type of vulnerability can be classified under the MITRE ATT&CK framework's technique T1083 for discovering system information, and potentially T1566 for initial access through web applications. The attack vector allows for systematic reconnaissance of the target system's file structure, enabling attackers to identify valuable targets for further exploitation.
Mitigation strategies for this vulnerability require immediate implementation of proper input validation and normalization procedures for all Unicode character sequences in file path requests. System administrators should upgrade to pWins Webserver versions that address this vulnerability through proper path canonicalization and Unicode normalization. The recommended approach involves implementing strict input filtering that rejects or normalizes Unicode sequences that could be used to manipulate file paths, ensuring that all path resolution operations occur within properly constrained directories. Additionally, implementing proper access controls and limiting file system permissions for the web server process can reduce the potential impact of successful exploitation attempts. Security monitoring should include detection of unusual file access patterns and path traversal attempts, while regular security audits should verify that all web applications properly validate and sanitize input parameters to prevent similar vulnerabilities from emerging in other components of the system architecture.