Network access: Restrict anonymous access to Named Pipes and Shares 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 HKLMSystem CurrentControlSetServicesLanManServerParameters 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.

[enable/disable]

(1) GPO: Computer ConfigurationWindows SettingsSecurity SettingsLocal PoliciesSecurity Options!Network access: Restrict anonymous access to Named Pipes and Shares (2) REG: HKEY_LOCAL_MACHINESystemCurrentControlSetServicesLanManServerParameters!restrictnullsessaccess