CVE-2002-2429 in WebServer
Summary
by MITRE
webs.c in GoAhead WebServer before 2.1.4 allows remote attackers to cause a denial of service (daemon crash) via an HTTP POST request that contains a negative integer in the Content-Length header.
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Analysis
by VulDB Data Team • 10/27/2018
The vulnerability identified as CVE-2002-2429 represents a critical denial of service flaw in the GoAhead WebServer software family, specifically within the webs.c component that handles HTTP request processing. This vulnerability affects versions prior to 2.1.4 and demonstrates a classic buffer overflow condition that occurs when the web server processes malformed HTTP POST requests containing negative integer values in the Content-Length header field. The issue stems from the web server's failure to properly validate or sanitize input parameters before processing them, creating an exploitable condition that can be leveraged by remote attackers to crash the web daemon service.
The technical implementation of this vulnerability involves the web server's parsing logic for HTTP headers, where the Content-Length field is expected to contain a positive integer representing the size of the request body. When a negative integer is provided in this field, the GoAhead WebServer's webs.c module fails to properly handle the invalid value, leading to unpredictable behavior during memory allocation or buffer management operations. This improper input validation creates a condition where the server attempts to allocate memory or process data structures using negative values, which can result in memory corruption, stack overflows, or other critical execution errors that ultimately cause the web daemon to terminate unexpectedly.
From an operational impact perspective, this vulnerability presents a significant risk to web server availability and system reliability. Remote attackers can exploit this weakness to perform denial of service attacks against vulnerable systems without requiring any authentication or privileged access. The attack vector is particularly dangerous because it can be executed through simple HTTP POST requests that can be crafted using standard web client tools or automated attack scripts. The resulting daemon crash effectively removes the web service from operation, potentially disrupting business-critical applications, user access to web resources, and overall system availability. This vulnerability directly maps to CWE-129, which addresses improper validation of input boundaries, and aligns with ATT&CK technique T1499.004 for network denial of service attacks.
The mitigation strategy for this vulnerability requires immediate implementation of the vendor-provided patch or upgrade to GoAhead WebServer version 2.1.4 or later, which includes proper input validation for Content-Length header values. Organizations should also implement network-level protections such as intrusion detection systems that can monitor for suspicious HTTP header patterns, particularly negative integers in Content-Length fields. Additionally, defensive configuration practices should include implementing rate limiting mechanisms and monitoring for unusual traffic patterns that may indicate exploitation attempts. System administrators should conduct thorough vulnerability assessments to identify all instances of affected GoAhead WebServer versions within their infrastructure and ensure comprehensive patch management procedures are in place to prevent similar issues from occurring in the future. The vulnerability highlights the critical importance of input validation in web server implementations and demonstrates how seemingly minor parsing errors can result in significant availability impacts.