Information
This policy setting controls the ability of anonymous users to enumerate the accounts in the Security Accounts Manager (SAM). If you enable this policy setting, users with anonymous connections cannot enumerate domain account user names on the workstations in your environment. This policy setting also allows additional restrictions on anonymous connections. An unauthorized user could anonymously list account names and use the information to perform social engineering attacks or attempt to guess passwords. (Social engineering attacks try to deceive users in some way to obtain passwords or some form of security information.)
Solution
To implement the recommended configuration state, set the following Group Policy setting to 1.
Computer Configuration\Windows Settings\Security Settings\Local Policies\Security Options\Network access- Do not allow anonymous enumeration of SAM accounts
Impact- It will be impossible to establish trusts with Windows NT 4.0 based domains. Also, client computers that run older versions of the Windows operating system such as Windows NT 3.51 and Windows 95 will experience problems when they try to use resources on the server.