Detections
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18.8.37.2 Ensure 'Restrict Unauthenticated RPC clients' is set to 'Enabled: Authenticated' (MS only)

Information

This policy setting controls how the RPC server runtime handles unauthenticated RPC clients connecting to RPC servers.

This policy setting impacts all RPC applications. In a domain environment this policy setting should be used with caution as it can impact a wide range of functionality including group policy processing itself. Reverting a change to this policy setting can require manual intervention on each affected machine. This policy setting should never be applied to a Domain Controller.

A client will be considered an authenticated client if it uses a named pipe to communicate with the server or if it uses RPC Security. RPC Interfaces that have specifically requested to be accessible by unauthenticated clients may be exempt from this restriction, depending on the selected value for this policy setting.

-- 'None' allows all RPC clients to connect to RPC Servers running on the machine on which the policy setting is applied.

-- 'Authenticated' allows only authenticated RPC Clients (per the definition above) to connect to RPC Servers running on the machine on which the policy setting is applied. Exemptions are granted to interfaces that have requested them.

-- 'Authenticated without exceptions' allows only authenticated RPC Clients (per the definition above) to connect to RPC Servers running on the machine on which the policy setting is applied. No exceptions are allowed. This value has the potential to cause serious problems and is not recommended.

Note: This policy setting will not be applied until the system is rebooted.

The recommended state for this setting is: Enabled: Authenticated.

Rationale:

Unauthenticated RPC communication can create a security vulnerability.




Impact:

Only authenticated RPC Clients will be allowed to connect to RPC servers running on the machine on which the policy setting is applied. Exemptions are granted to interfaces that have requested them.

Solution

To establish the recommended configuration via GP, set the following UI path to Enabled: Authenticated:

Computer Configuration\Policies\Administrative Templates\System\Remote Procedure Call\Restrict Unauthenticated RPC clients

Note: This Group Policy path may not exist by default. It is provided by the Group Policy template RPC.admx/adml that is included with the Microsoft Windows 8.0 & Server 2012 (non-R2) Administrative Templates (or newer).

Default Value:

Enabled: None. (All RPC clients are allowed to connect to RPC servers running on the machine.)

See Also

https://workbench.cisecurity.org/files/3458

Item Details

References: CSCv6|9.1, CSCv7|9.2

Plugin: Windows

Control ID: dcf0de9dfc37aa4ce3c5ff159a4f5be876a845f5702b79158a3a3b06e479c82d