When enabled, this security setting restricts anonymous access to shares and pipes to the settings for: Network access: Named pipes that can be accessed anonymously Network access: Shares that can be accessed anonymously Default: Enabled. When enabled, this policy setting restricts anonymous access to only those shares and pipes that are named in the Network access: Named pipes that can be accessed anonymously and Network access: Shares that can be accessed anonymously settings. This policy setting controls null session access to shares on your computers by adding RestrictNullSessAccess with the value 1 in the HKLM\System\CurrentControlSet\Services\LanManServer\Parameters registry key. This registry value toggles null session shares on or off to control whether the server service restricts unauthenticated clients' access to named resources. Null sessions are a weakness that can be exploited through shares (including the default shares) on computers in your environment. Fix: (1) GPO: Computer Configuration\Windows Settings\Security Settings\Local Policies\Security Options!Network access: Restrict anonymous access to Named Pipes and Shares (2) REG: HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\LanManServer\Parameters!restrictnullsessaccess