CVE-2000-0480 in Dragon Server
Summary
by MITRE
Dragon telnet server allows remote attackers to cause a denial of service via a long username.
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Analysis
by VulDB Data Team • 03/12/2025
The vulnerability identified as CVE-2000-0480 affects the Dragon telnet server implementation, presenting a classic denial of service weakness that has persisted in network services for decades. This vulnerability resides in the server's handling of user authentication inputs, specifically when processing username parameters during telnet session establishment. The flaw manifests when an attacker submits an excessively long username string to the telnet server, causing the service to crash or become unresponsive. The Dragon telnet server, like many legacy network services of its era, lacked proper input validation mechanisms to handle malformed or excessively large data payloads, creating a predictable attack vector that could be exploited without requiring authentication or specialized privileges.
The technical root cause of this vulnerability aligns with CWE-122, which describes buffer overflow conditions where insufficient bounds checking allows attackers to write beyond allocated memory buffers. In this case, the telnet server's username processing routine fails to validate input length before attempting to store or process the authentication data. When the server receives a username exceeding its internal buffer capacity, the overflow condition triggers system instability, typically resulting in the termination of the telnet service process or complete system hang. The vulnerability operates at the application layer of the network stack, specifically within the authentication handling component, making it particularly dangerous as it can be exploited remotely without requiring physical access or prior system compromise.
The operational impact of CVE-2000-0480 extends beyond simple service disruption, representing a fundamental security weakness that could be leveraged as part of broader attack campaigns. Network administrators face significant challenges when dealing with such vulnerabilities, as they often cannot distinguish between legitimate user errors and malicious exploitation attempts. The denial of service condition affects availability, violating the core principles of the CIA triad and potentially disrupting critical business operations that depend on remote access capabilities. Organizations utilizing Dragon telnet servers without proper patching or mitigation strategies risk complete service outages, especially in environments where telnet remains the primary remote administration protocol. The vulnerability also demonstrates poor software engineering practices that were common in legacy network service implementations, where security considerations were often secondary to functionality and ease of deployment.
Mitigation strategies for this vulnerability should encompass both immediate remediation and long-term architectural improvements. The most effective immediate solution involves applying vendor patches or upgrading to newer versions of the telnet server software that properly validate input lengths and implement robust buffer management techniques. Network administrators should also implement rate limiting and connection throttling mechanisms to prevent exploitation attempts from overwhelming the service. Additionally, the use of more secure remote access protocols such as ssh should be strongly considered as replacements for telnet, as ssh implementations generally provide better protection against such buffer overflow conditions. From an operational security perspective, implementing intrusion detection systems that monitor for unusual username length patterns can help identify exploitation attempts before they cause significant disruption. The vulnerability also highlights the importance of following security standards such as those defined by the Center for Internet Security and NIST guidelines for secure system configuration, emphasizing the need for regular security assessments and vulnerability management processes that can identify and remediate similar weaknesses in network infrastructure components.