CVE-2000-0647 in WFTPD
Summary
by MITRE
WFTPD and WFTPD Pro 2.41 allows remote attackers to cause a denial of service by executing an MLST command before logging into the server.
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Analysis
by VulDB Data Team • 03/19/2025
The vulnerability identified as CVE-2000-0647 affects WFTPD and WFTPD Pro version 2.41, representing a significant security flaw in file transfer protocols that can be exploited to disrupt service availability. This issue manifests through a specific command execution sequence that bypasses normal authentication procedures, allowing malicious actors to trigger a denial of service condition without proper credentials. The vulnerability resides in the protocol implementation where the MLST command processing occurs before the authentication phase, creating an exploitable entry point that undermines the server's normal operational flow.
The technical flaw stems from improper input validation and command processing within the FTP server implementation where the MLST command is accepted and processed prior to user authentication. This design flaw creates a condition where remote attackers can send the MLST command to the server and observe the system behavior without providing valid login credentials. The command execution bypasses normal access controls and authentication mechanisms, effectively allowing unauthorized users to probe the server's response patterns and potentially cause resource exhaustion or system instability. This type of vulnerability aligns with CWE-20, which addresses improper input validation, and represents a classic case of insecure command processing in network services.
The operational impact of this vulnerability extends beyond simple service disruption, as it provides attackers with a method to probe server configurations and potentially gather information about the system before attempting more sophisticated attacks. Remote attackers can leverage this vulnerability to perform reconnaissance activities that might reveal system details, file structures, or other sensitive information that could be used in subsequent exploitation attempts. The denial of service condition can be particularly damaging in environments where continuous availability is critical, as it allows attackers to disrupt legitimate user access and potentially mask other malicious activities. This vulnerability also demonstrates poor separation of concerns in the protocol implementation, where administrative commands should not be executable without proper authentication.
Mitigation strategies for CVE-2000-0647 should focus on implementing proper command validation and authentication sequence enforcement within the FTP server implementation. System administrators should ensure that all FTP servers are updated to versions that properly validate command execution before authentication, preventing commands like MLST from being processed without proper user credentials. Network segmentation and firewall rules should be implemented to restrict access to FTP services, limiting exposure to unauthorized users. Additionally, implementing intrusion detection systems that monitor for unusual command sequences or unauthorized access attempts can provide early warning of potential exploitation attempts. The vulnerability highlights the importance of following secure coding practices and adhering to the principle of least privilege in network service implementations, where commands should only be executable after proper authentication and authorization checks have been completed. Organizations should also consider implementing additional logging and monitoring capabilities to detect and respond to potential exploitation attempts effectively.