CVE-2000-0301 in IMail
Summary
by MITRE
Ipswitch IMAIL server 6.02 and earlier allows remote attackers to cause a denial of service via the AUTH CRAM-MD5 command.
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Analysis
by VulDB Data Team • 04/21/2026
The vulnerability identified as CVE-2000-0301 affects Ipswitch IMAIL server versions 6.02 and earlier, presenting a significant security weakness that enables remote attackers to execute denial of service attacks through specifically crafted AUTH CRAM-MD5 commands. This vulnerability resides within the email server's authentication mechanism, specifically targeting the cryptographic authentication protocol implementation that was commonly used in email systems during the late 1990s and early 2000s. The flaw represents a classic example of insufficient input validation and error handling within network services, where the server fails to properly process malformed or unexpected authentication requests, leading to system instability and potential service disruption.
The technical nature of this vulnerability stems from the server's inadequate handling of the CRAM-MD5 authentication mechanism, which is a challenge-response authentication protocol that uses MD5 hashing for security. When an attacker sends a specially crafted AUTH CRAM-MD5 command to the IMAIL server, the server's authentication handler does not properly validate the input parameters or handle malformed responses, causing the server to crash or become unresponsive. This behavior aligns with CWE-20, which describes improper input validation, and CWE-122, which addresses buffer overflow conditions. The vulnerability operates at the application layer of the network stack, making it particularly dangerous as it requires no authentication to exploit and can be executed from any remote location with network access to the affected server's SMTP port.
The operational impact of this vulnerability extends beyond simple service interruption, as it can potentially disrupt email communications for organizations relying on the affected IMAIL server. When exploited successfully, the denial of service condition can prevent legitimate users from sending or receiving emails, effectively shutting down email services until the server is manually restarted or the vulnerability is patched. The attack vector is particularly concerning because it leverages standard email authentication protocols that are widely implemented and expected to function correctly, making the vulnerability difficult to detect through normal network monitoring. Organizations with multiple email servers running vulnerable versions of IMAIL would face cascading failures if the vulnerability were exploited across their infrastructure, as the compromised server could potentially affect broader email delivery systems.
Mitigation strategies for this vulnerability should prioritize immediate patching of affected systems, as Ipswitch released updates specifically addressing this issue in later versions of their IMAIL server software. Network administrators should implement firewall rules to restrict access to the SMTP service where possible, though this approach provides only partial protection since the vulnerability can be exploited from any network location with access to the service. The implementation of intrusion detection systems that monitor for suspicious authentication patterns may help identify exploitation attempts, while regular security audits should verify that all email servers in the organization are running patched versions. This vulnerability also highlights the importance of proper error handling in network services and demonstrates how seemingly benign protocol implementations can become attack vectors when proper input validation is not implemented, aligning with ATT&CK technique T1499 which covers network denial of service attacks. Organizations should also consider implementing redundant email services and backup communication channels to maintain business continuity in case of successful exploitation.
The vulnerability serves as an important historical example of how authentication mechanisms, when not properly secured, can become attack vectors rather than security controls. It demonstrates the critical need for comprehensive security testing of protocol implementations and the importance of validating all inputs received from untrusted sources. Modern security practices have evolved to address these types of issues through better input sanitization, robust error handling, and more rigorous security testing procedures, though similar vulnerabilities continue to be discovered in legacy systems that have not been properly updated or maintained over time.