CVE-2000-0479 in Dragon Server
Summary
by MITRE
Dragon FTP server allows remote attackers to cause a denial of service via a long USER command.
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Analysis
by VulDB Data Team • 05/11/2019
The vulnerability identified as CVE-2000-0479 affects the Dragon FTP server implementation, presenting a classic denial of service weakness through improper input validation. This flaw specifically manifests when the server receives an excessively long USER command from remote attackers, demonstrating a fundamental lack of bounds checking in the authentication handling process. The vulnerability resides in the server's failure to properly sanitize or limit the length of user credentials provided during the login sequence, creating an exploitable condition that can be leveraged to disrupt service availability.
From a technical perspective, this vulnerability represents a buffer overflow condition or excessive string handling issue that occurs during the USER command processing phase of the ftp protocol implementation. The Dragon FTP server does not enforce reasonable limits on the length of the username parameter, allowing attackers to craft malicious commands containing oversized data payloads. When the server attempts to process these malformed inputs, it typically results in memory corruption, stack overflow conditions, or resource exhaustion that ultimately leads to service termination or system instability. This behavior aligns with CWE-122 buffer overflow vulnerabilities and represents a common weakness in legacy ftp server implementations that predate modern security hardening practices.
The operational impact of this vulnerability extends beyond simple service disruption, as it provides attackers with a straightforward method to compromise system availability without requiring authentication or advanced exploitation techniques. Remote attackers can exploit this weakness from any network location to initiate denial of service attacks against targeted ftp servers, potentially affecting legitimate users who rely on these services for file transfers and data access. The attack vector is particularly concerning because it requires minimal technical expertise to execute, making it a preferred method for attackers seeking to disrupt operations. This vulnerability directly maps to attack techniques described in the MITRE ATT&CK framework under the denial of service category, specifically targeting network service availability through protocol-level exploitation.
Mitigation strategies for CVE-2000-0479 should focus on implementing input validation controls and establishing reasonable parameter limits for user authentication commands. System administrators should configure the Dragon FTP server to enforce maximum length restrictions on USER command parameters, typically limiting username inputs to reasonable lengths such as 255 characters or fewer. Additionally, implementing proper error handling and graceful degradation mechanisms can help prevent complete service failures when malformed inputs are detected. Network-level protections such as firewall rules that limit connection rates and implement rate limiting can provide additional defense in depth. Organizations should also consider upgrading to modern ftp server implementations that have been hardened against such vulnerabilities, as the Dragon FTP server is a legacy implementation that lacks contemporary security features. The vulnerability demonstrates the importance of input sanitization practices and proper bounds checking that align with security best practices outlined in industry standards and frameworks.