Configure the SPN target name validation level.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-21950	3.150	SV-25273r1_rule	ECSC-1	Medium

Description
This setting helps prevent spoofing; ensuring that if a service principle name (SPN) is provided by the client, it is validated against the server’s list of SPNs.

STIG	Date
Windows 7 Security Technical Implementation Guide	2015-03-09

Details

Check Text ( C-26832r1_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 “Accept if provided by client”, 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: 1

Check Text ( C-26832r1_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 “Accept if provided by client”, 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: 1

Fix Text (F-22939r1_fix)
Configure the policy value for “Microsoft network server: Server SPN target name validation level” to “Accept if provided by client”.