CVE-1999-0549 in Windows
Summary
by MITRE
Windows NT automatically logs in an administrator upon rebooting.
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Analysis
by VulDB Data Team • 04/18/2026
This vulnerability exists in windows nt operating systems where the system automatically logs in an administrator account without requiring authentication upon rebooting. The flaw stems from improper default configuration settings that bypass standard security protocols for user authentication during system startup. The vulnerability is categorized under cwe-287 which addresses improper authentication mechanisms and aligns with att&ck technique t1078 002 focusing on valid accounts exploitation through legitimate system access methods. The issue occurs because windows nt fails to properly enforce authentication requirements during the boot process, allowing unauthorized access to administrative privileges immediately upon system restart.
The technical implementation of this vulnerability involves the operating system's login service failing to properly validate user credentials when the system transitions from the boot phase to the login screen. During the reboot process, windows nt executes a default login sequence that automatically selects and logs in the highest privilege account available on the system without prompting for password verification. This behavior represents a fundamental breakdown in the principle of least privilege and creates a persistent security weakness that remains active until the system is properly configured by an administrator.
The operational impact of this vulnerability is significant as it provides immediate administrative access to any user who can physically access the system or has the ability to trigger a reboot. Attackers can exploit this weakness by simply rebooting the system to gain full administrative control without needing to know passwords or credentials. This vulnerability particularly affects systems where physical security is compromised or where unauthorized users have access to system reboot capabilities. The risk is amplified in enterprise environments where multiple users may have physical access to servers or workstations, creating potential for privilege escalation attacks.
Mitigation strategies for this vulnerability involve proper system configuration and security hardening practices. Administrators should disable automatic login features and ensure that all systems require explicit authentication before granting access to administrative accounts. The recommended approach includes configuring the system to prompt for credentials during boot-up, implementing proper account management policies, and ensuring that only authorized personnel have physical access to systems. Additional security measures should include regular auditing of system configurations, implementation of secure boot processes, and adherence to security baselines that prevent automatic privilege escalation during system startup. The vulnerability demonstrates the importance of proper default security configurations and the need for comprehensive system hardening procedures.