This policy setting determines the number of failed logon attempts before a lock occurs. Authorized users can lock themselves out of an account by mistyping their password or by remembering it incorrectly, or by changing their password on one computer while logged on to another computer. The computer with the incorrect password will continuously try to authenticate the user, and because the password it uses to authenticate is incorrect, a lock occurs. To avoid accidental lockout of authorized users, set the account lockout threshold to a high number. The default value for this policy setting is 0 invalid logon attempts, which disables the account lockout feature. Because it is possible for an attacker to use this lockout state as a denial of service (DoS) by triggering a lockout on a large number of accounts, your organization should determine whether to use this policy setting based on identified threats and the risks you want to mitigate. There are two options to consider for this policy setting. - Configure the value for Account lockout threshold to 0 to ensure that accounts will not be locked out. This setting value will prevent a DoS attack that attempts to lock out accounts in your organization. It will also reduce help desk calls, because users will not be able to lock themselves out of their accounts accidentally. However, this setting value will not prevent a brute force attack. The following defenses should also be considered: - A password policy that forces all users to have complex passwords made up of 8 or more characters. - A robust auditing mechanism, which will alert administrators when a series of account lockouts occurs in the environment. For example, the auditing solution should monitor for security event 539, which is a logon failure. This event identifies that there was a lock on the account at the time of the logon attempt. The second option is: - Configure the value for Account lockout threshold to a value that provides users with the ability to mistype their password several times, but locks out the account if a brute force password attack occurs. This configuration will prevent accidental account lockouts and reduce help desk calls, but will not prevent a DoS attack. Fix: (1) GPO: Computer Configuration\Windows Settings\Security Settings\Account Policies\Account Lockout Policy!Account lockout threshold (2) WMI: ###