Network access: Do not allow anonymous enumeration of SAM accounts and shares
Computer Configuration\Windows Settings\Security Settings\Local Policies\Security Options
Determines whether anonymous enumeration of SAM accounts and shares is allowed.
Windows allows anonymous users to perform certain activities, such as enumerating the names of domain accounts and network shares. This is convenient, for example, when an administrator wants to grant access to users in a trusted domain that does not maintain a reciprocal trust. If you do not want to allow anonymous enumeration of SAM accounts and shares, then enable this policy.
For more information, see: