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

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-21950	3.150	SV-32441r1_rule	ECSC-1	Medium

Description
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.

STIG	Date
Windows Server 2008 R2 Domain Controller Security Technical Implementation Guide	2013-03-14

Details

Check Text ( C-32782r1_chk )
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

Check Text ( C-32782r1_chk )

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 (F-28855r1_fix)
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”.