CVE-2000-0593 in WinProxy
Summary
by MITRE
WinProxy 2.0 and 2.0.1 allows remote attackers to cause a denial of service by sending an HTTP GET request without listing an HTTP version number.
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Analysis
by VulDB Data Team • 05/26/2018
The vulnerability identified as CVE-2000-0593 represents a classic denial of service flaw in the WinProxy proxy server software version 2.0 and 2.0.1. This issue stems from the software's inadequate handling of malformed HTTP requests, specifically those lacking the required HTTP version specification in the GET request line. The flaw demonstrates a fundamental weakness in input validation and request parsing mechanisms that are critical for proxy server operation. When a remote attacker crafts an HTTP GET request that omits the HTTP version number, the WinProxy server fails to properly process this malformed request, leading to system instability and potential service disruption.
The technical root cause of this vulnerability lies in the proxy server's failure to validate the completeness of HTTP request syntax before attempting to process it. According to the HTTP specification defined in RFC 2616, all HTTP requests must include a valid request line that contains the method, request URI, and HTTP version. When WinProxy encounters a GET request missing the HTTP version component, the software's parsing logic becomes confused and cannot properly determine how to handle the request. This parsing failure creates a condition where the server either crashes or enters a state where it cannot process subsequent legitimate requests, effectively rendering the proxy service unavailable to authorized users.
From an operational impact perspective, this vulnerability presents a significant risk to organizations relying on WinProxy for network traffic management and security enforcement. The denial of service condition can be easily exploited by any remote attacker with basic network connectivity to the affected proxy server, requiring no special privileges or advanced technical skills. The attack vector is particularly dangerous because it can be executed silently without leaving obvious traces in system logs, making it difficult to detect and attribute. Organizations may experience complete disruption of their proxy services, leading to network outages that affect multiple users and applications depending on the proxy for internet access and security filtering.
The vulnerability maps directly to CWE-129, which addresses improper validation of input length or range, and also aligns with ATT&CK technique T1499.004 for network denial of service attacks. The flaw demonstrates poor error handling practices and inadequate robustness in network protocol implementation. Organizations should implement immediate mitigations including updating to patched versions of WinProxy software, implementing network segmentation to limit exposure, and deploying intrusion detection systems to monitor for malformed HTTP requests. Additionally, network administrators should consider implementing rate limiting and request validation rules at the network perimeter to prevent exploitation. The incident underscores the critical importance of robust input validation and proper error handling in network security appliances, as even simple protocol violations can result in complete service disruption.