CVE-2002-1866 in Simple Web Server
Summary
by MITRE
Simple Web Server (SWS) 0.0.4 through 0.1.0 does not close file descriptors for 404 error messages, which could allow remote attackers to cause a denial of service (file descriptor exhaustion) via multiple requests for pages that do not exist.
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Analysis
by VulDB Data Team • 07/05/2024
The vulnerability identified as CVE-2002-1866 affects Simple Web Server version 0.0.4 through 0.1.0, representing a critical resource management flaw that can lead to denial of service conditions. This issue stems from improper handling of file descriptors within the web server's error response mechanism, specifically when processing requests for non-existent resources. The flaw demonstrates a fundamental lack of proper resource cleanup in the server's error handling code path, creating a persistent resource leak that can be exploited by remote attackers.
The technical implementation of this vulnerability resides in the server's failure to properly close file descriptors associated with 404 error responses. When a client makes a request for a non-existent page, the server generates a 404 error message but fails to release the file descriptor resources that were allocated during the error processing. This creates a scenario where each failed request consumes additional file descriptor resources without proper cleanup, leading to progressive resource exhaustion over time. The vulnerability operates at the operating system level where file descriptors are limited system resources, typically constrained by the maximum file descriptor limit per process.
From an operational perspective, this vulnerability presents a significant risk to web server availability and system stability. Attackers can systematically exploit this weakness by sending multiple requests for non-existent pages, causing the server to consume all available file descriptors and eventually become unable to handle legitimate requests. The impact extends beyond simple service disruption to potentially affecting other system processes that depend on file descriptor availability, creating cascading failures within the hosting environment. This type of resource exhaustion attack aligns with the common attack pattern of consuming system resources to prevent legitimate service delivery, which is documented in the attack tactics framework.
The vulnerability demonstrates characteristics consistent with CWE-404, which describes improper resource cleanup or release, and relates to the broader category of resource management flaws that affect system stability and availability. From a defensive standpoint, the primary mitigation strategy involves implementing proper resource management practices within the server code, specifically ensuring that all file descriptors are closed regardless of the error condition encountered. This requires modifying the server's error handling routines to explicitly close file descriptors before terminating error response processing. Additionally, implementing connection limits, request rate limiting, and proper resource monitoring can help detect and prevent exploitation attempts. The remediation approach should follow established security practices for preventing resource exhaustion attacks as outlined in various cybersecurity frameworks, ensuring that all system resources are properly managed throughout the application lifecycle.