Under certain circumstances, it is possible to bypass a domain account lockout policy on a local machine which would render this protective measure against brute force password attempts ineffective. The purpose of a domain account lockout policy is to disable an account after a certain number of unsuccessful login attempts. If this policy was not implemented, the password of a domain account could be guessed an unlimited number of times. Windows 2000 hosts in a non-2000 domain using NTLM authentication will fail to recognize a domain account lockout policy for users whose credentials are locally cached. Cached credentials contain the username and password in hashed form and are used in the event that the domain controller is not available to perform authentication. Windows 2000 systems that are not using NTLM to perform authentication are not susceptible to this vulnerability, therefore clients that are members of Windows 2000 domains would not be vulnerable because Kerberos...
Under certain circumstances, it is possible to bypass a domain account lockout policy on a local machine which would render this protective measure against brute force password attempts ineffective. The purpose of a domain account lockout policy is to disable an account after a certain number of unsuccessful login attempts. If this policy was not implemented, the password of a domain account could be guessed an unlimited number of times. Windows 2000 hosts in a non-2000 domain using NTLM authentication will fail to recognize a domain account lockout policy for users whose credentials are locally cached. Cached credentials contain the username and password in hashed form and are used in the event that the domain controller is not available to perform authentication. Windows 2000 systems that are not using NTLM to perform authentication are not susceptible to this vulnerability, therefore clients that are members of Windows 2000 domains would not be vulnerable because Kerberos authentication is being implemented. This vulnerability would allow for the possibility of successful retrieval of a valid password through the use of brute force techniques. If a malicious user was able to login with a password acquired from a brute force attack, they would gain privileges of the same level as the domain account but would be confined to the local machine because domain authentication would not be able to take place and the lockout policy would be exercised at the domain level.
