CVE-2000-0056 in IMail
Summary
by MITRE
IMail IMONITOR status.cgi CGI script allows remote attackers to cause a denial of service with many calls to status.cgi.
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Analysis
by VulDB Data Team • 10/19/2025
The vulnerability identified as CVE-2000-0056 affects the IMail email server software, specifically targeting the IMONITOR component that handles web-based status reporting through the status.cgi CGI script. This flaw represents a classic denial of service vulnerability that exploits the lack of proper input validation and resource management within the web server interface. The IMail server, widely used in enterprise environments during the late 1990s and early 2000s, provided both email and web server functionality through its integrated IMONITOR service. The status.cgi script serves as a monitoring interface that allows administrators to check the server status and various operational parameters through web requests.
The technical flaw manifests when remote attackers repeatedly invoke the status.cgi CGI script with multiple concurrent requests or rapid successive calls. This behavior causes the IMail server to consume excessive system resources, particularly memory and processor cycles, as each request triggers internal processing routines that may not properly handle the volume of concurrent operations. The vulnerability operates at the application layer and can be classified under CWE-400 as an Uncontrolled Resource Consumption, specifically related to insufficient resource management. The flaw does not require authentication or special privileges to exploit, making it particularly dangerous as any remote attacker can initiate the attack without prior access to the system.
The operational impact of this vulnerability extends beyond simple service disruption, as it can effectively render the entire IMail server unusable for legitimate users. When exploited successfully, the denial of service condition can persist for extended periods until the server is manually restarted or the excessive resource consumption subsides. This vulnerability particularly affects organizations that rely on IMail for business-critical email services, as it can cause significant downtime and potentially impact business operations. The attack vector operates through standard HTTP requests to the web server port, typically port 80, making it easily executable from any internet-connected device without requiring specialized tools or techniques.
The security implications of CVE-2000-0056 align with ATT&CK technique T1499.004, which covers Network Denial of Service, and demonstrates how web-based interfaces can become attack vectors for resource exhaustion attacks. Organizations using IMail servers were particularly vulnerable because the software was designed without adequate rate limiting or resource throttling mechanisms to prevent such abuse. The vulnerability highlights the importance of implementing proper input validation and resource management in web applications, particularly those serving monitoring and administrative functions. Effective mitigations include implementing request rate limiting on the web server, configuring proper resource limits for CGI processes, and applying the vendor-provided security patches that address the excessive resource consumption issue. Additionally, network-level firewalls and intrusion detection systems can help detect and block excessive traffic patterns that indicate exploitation attempts, though the most effective solution remains the application of proper security updates and the implementation of robust resource management practices.