CVE-1999-0200 in Windows
Summary
by MITRE
Windows NT FTP server (WFTP) with the guest account enabled without a password allows an attacker to log into the FTP server using any username and password.
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Analysis
by VulDB Data Team • 06/23/2021
The vulnerability described in CVE-1999-0200 represents a critical authentication flaw in the Windows NT FTP server implementation that fundamentally undermines the security model of the system. This issue affects the Windows NT operating system's built-in File Transfer Protocol server component known as WFTP, which was designed to provide basic file sharing capabilities over network connections. The vulnerability stems from a misconfiguration that occurs when the guest account is enabled without proper password protection, creating an authentication bypass that allows any attacker to gain unauthorized access to the FTP server regardless of their credentials.
The technical nature of this flaw resides in the server's authentication mechanism where the guest account, intended as a limited access point for users, becomes completely accessible without any credential verification. When the guest account is enabled without a password, the WFTP server fails to properly enforce authentication requirements, allowing attackers to establish FTP sessions using arbitrary username and password combinations. This represents a classic case of improper access control where the system does not properly validate user credentials before granting access privileges. The vulnerability operates at the application layer and affects the authentication subsystem of the Windows NT operating system, making it particularly dangerous as it bypasses normal security controls that should prevent unauthorized access to file sharing resources.
The operational impact of this vulnerability extends far beyond simple unauthorized file access, as it provides attackers with complete control over the FTP server and potentially the underlying file system. An attacker who successfully exploits this vulnerability can upload, download, modify, or delete files on the server, execute commands, and potentially escalate privileges to gain broader system access. This vulnerability directly violates the principle of least privilege and creates an entry point that could be exploited as part of a larger attack chain. The impact is particularly severe in enterprise environments where Windows NT servers may host sensitive data or serve as part of critical infrastructure, as the vulnerability allows for persistent access that could go undetected for extended periods. Organizations using this service without proper security hardening could face data breaches, system compromise, and potential regulatory violations.
The mitigation strategies for this vulnerability focus primarily on proper configuration management and access control enforcement. System administrators must ensure that the guest account is either disabled entirely or properly secured with strong authentication credentials when enabled. The recommended approach involves disabling the guest account on FTP servers unless absolutely necessary for specific legitimate business requirements, and implementing proper access control lists that restrict FTP access to authorized users only. Security best practices dictate that all network services should be configured with the principle of least privilege, where access is granted based on specific need rather than default permissions. This vulnerability aligns with CWE-284, which describes improper access control issues, and could be leveraged by attackers following ATT&CK tactics such as T1133 for external remote access and T1078 for valid accounts. Regular security audits and configuration reviews should be implemented to ensure that FTP services are properly secured and that default configurations are not left in place, as this vulnerability demonstrates the critical importance of proper service hardening in preventing unauthorized access to network resources.