The service principal name (SPN) target name validation level will be turned off.

From Windows Server 2008 R2 Domain Controller Security Technical Implementation Guide

Part of SPN Target Name Validation Level

Associated with: CCI-000366

SV-32441r1_rule The service principal name (SPN) target name validation level will be turned off.

Vulnerability discussion

If a service principle name (SPN) is provided by the client, it is validated against the server’s list of SPNs. This setting can cause disruptions in file and printer services.

Check content

Analyze the system using the Security Configuration and Analysis snap-in. Expand the Security Configuration and Analysis tree view. Navigate to Local Policies -> Security Options. If the value for “Microsoft network server: Server SPN target name validation level” is not set to “Off”, then this is a finding. The policy referenced configures the following registry value: Registry Hive: HKEY_LOCAL_MACHINE Subkey: \System\CurrentControlSet\Services\LanmanServer\Parameters\ Value Name: SmbServerNameHardeningLevel Type: REG_DWORD Value: 0

Fix text

Configure the policy value for Computer Configuration -> Windows Settings -> Security Settings -> Local Policies -> Security Options -> “Microsoft Network Server: Server SPN target name validation level” to “Off”.

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