CVE-2002-1663 in HTTP Daemon
Summary
by MITRE
The Post_Method function in method.c for Monkey HTTP Daemon before 0.5.1 allows remote attackers to cause a denial of service (crash) via a POST request with an invalid or missing Content-Length header value.
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Analysis
by VulDB Data Team • 09/02/2025
The vulnerability identified as CVE-2002-1663 resides within the Monkey HTTP Daemon software version 0.5.1 and earlier, specifically within the Post_Method function located in the method.c source file. This flaw represents a critical security weakness that can be exploited by remote attackers to execute a denial of service attack against the affected web server. The vulnerability manifests when the HTTP daemon processes POST requests that contain either malformed or absent Content-Length header values, creating a condition that leads to application instability and eventual system crash.
The technical implementation of this vulnerability stems from inadequate input validation within the HTTP request processing pipeline of the Monkey daemon. When a POST request is received without a proper Content-Length header or with an invalid value, the Post_Method function fails to properly handle this edge case, resulting in a crash of the entire HTTP daemon process. This represents a classic buffer over-read or improper state handling vulnerability, where the software does not adequately validate the presence and correctness of HTTP headers before proceeding with request processing. The absence of proper error handling mechanisms means that malformed headers cause the application to enter an undefined state, leading to the termination of the service.
The operational impact of this vulnerability extends beyond simple service disruption, as it can be leveraged by attackers to systematically degrade service availability for legitimate users. Remote attackers can craft malicious POST requests with crafted Content-Length values to trigger the daemon crash, potentially leading to sustained denial of service conditions. This vulnerability particularly affects web applications and services that rely on the Monkey HTTP Daemon for serving content, making it a significant concern for organizations running this specific software stack. The attack can be executed with minimal resources and technical expertise, making it a preferred method for attackers seeking to disrupt web services.
From a cybersecurity perspective, this vulnerability aligns with CWE-122, which describes buffer overflow conditions, and represents a form of resource exhaustion attack that can be classified under the ATT&CK technique T1499.1, specifically targeting network denial of service. The vulnerability demonstrates poor input validation practices and highlights the importance of implementing robust error handling mechanisms in web server software. Organizations should prioritize immediate patching of affected systems to address this vulnerability, as the Monkey HTTP Daemon version 0.5.1 and earlier are no longer supported and contain multiple other security weaknesses. Recommended mitigations include upgrading to version 0.5.1 or later, implementing network-level protections such as rate limiting and header validation, and configuring intrusion detection systems to monitor for suspicious POST request patterns that could indicate exploitation attempts.