CVE-2002-0448 in Web Server
Summary
by MITRE
Xerver Free Web Server 2.10 and earlier allows remote attackers to cause a denial of service (crash) via an HTTP request that contains many "C:/" sequences.
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Analysis
by VulDB Data Team • 09/17/2025
The vulnerability identified as CVE-2002-0448 represents a classic denial of service flaw in the Xerver Free Web Server version 2.10 and earlier. This issue stems from the server's inadequate handling of malformed HTTP requests that contain an excessive number of "C:/" sequences within the request path. The vulnerability demonstrates a fundamental weakness in input validation and request parsing mechanisms that are critical for web server security. When a remote attacker crafts an HTTP request containing numerous consecutive "C:/" sequences, the server fails to properly process this malformed input and subsequently crashes or becomes unresponsive. This behavior constitutes a significant security concern as it allows unauthorized users to disrupt the availability of web services without requiring any authentication or privileged access. The flaw specifically targets the server's response handling logic, where it attempts to process these malformed sequences in a manner that leads to resource exhaustion or stack corruption. From a cybersecurity perspective, this vulnerability aligns with CWE-129, which addresses improper validation of input length or count, and more specifically with CWE-400, which covers unspecified denial of service conditions. The attack vector is particularly concerning as it requires no specialized tools or knowledge beyond basic HTTP request construction, making it accessible to a broad range of potential attackers. The operational impact extends beyond simple service disruption, as it can lead to complete server unavailability and may affect other services running on the same infrastructure. The vulnerability's exploitation directly violates the principle of robustness in network protocols, where servers should gracefully handle malformed input rather than crashing or becoming unresponsive. This type of vulnerability is particularly dangerous in production environments where web servers are critical components of business operations, as it can be used to perform coordinated attacks against web applications or to disrupt legitimate service delivery.
The technical implementation of this vulnerability reveals a lack of proper bounds checking and input sanitization within the Xerver Free Web Server's HTTP request parser. When the server receives an HTTP request containing multiple "C:/" sequences, the parsing algorithm likely attempts to resolve or normalize these paths in a way that consumes excessive system resources or triggers a buffer overflow condition. The specific sequence "C:/" suggests that the server may be interpreting these as drive letter specifications, which could lead to path traversal logic being executed inappropriately. This type of processing error falls under ATT&CK technique T1499.004, which describes network denial of service attacks that target web services. The server's failure to implement proper request length limits or to sanitize input sequences before processing creates an exploitable condition where an attacker can craft a request that causes the server to consume all available resources or execute invalid operations. The vulnerability's severity is amplified by the fact that it can be triggered through simple HTTP GET or POST requests, making it particularly dangerous for publicly accessible web servers. Modern security frameworks would recommend implementing strict input validation, request size limitations, and proper error handling to prevent such conditions from occurring. The lack of these protections in the affected Xerver versions demonstrates a critical gap in the software's security architecture, particularly in handling malformed input that could be used to exploit memory management issues or resource exhaustion conditions. This vulnerability serves as a historical example of why input validation and robust error handling are fundamental requirements in web server implementations.
Mitigation strategies for CVE-2002-0448 should focus on immediate patching of the affected Xerver Free Web Server versions to address the underlying parsing logic flaw. Organizations should implement network-level protections such as rate limiting and request filtering to prevent exploitation attempts from reaching vulnerable servers. The implementation of web application firewalls or intrusion prevention systems can help detect and block malformed HTTP requests containing excessive "C:/" sequences. Security teams should also consider implementing monitoring and alerting mechanisms to detect unusual server behavior that might indicate exploitation attempts. From a defensive standpoint, this vulnerability highlights the importance of validating all input at multiple layers of the network stack and implementing proper resource limits to prevent exploitation. The fix should include implementing proper bounds checking on request parameters, limiting the maximum length of path sequences, and ensuring that path resolution logic properly handles malformed inputs without crashing. Organizations should also review their web server configurations to ensure that default settings do not leave unnecessary services exposed and implement proper logging to track potential exploitation attempts. The vulnerability's characteristics align with the need for implementing the principle of least privilege and defense in depth strategies, where multiple layers of protection work together to prevent successful exploitation. Additionally, regular security assessments and vulnerability scanning should be conducted to identify similar issues in other web server implementations that may exhibit similar patterns of input handling flaws. This vulnerability demonstrates the critical importance of maintaining up-to-date security patches and implementing proper security testing procedures during software development and deployment phases. The long-term solution involves establishing robust security development lifecycle practices that incorporate threat modeling, secure coding standards, and comprehensive testing of input validation mechanisms to prevent similar issues from occurring in future software releases.