Windows Server 2022 must prevent PKU2U authentication using online identities.

STIG ID: WN22-SO-000280  |  SRG: SRG-OS-000480-GPOS-00227 |  Severity: medium |  CCI: CCI-000366 |  Vulnerability Id: V-254472 | 

Vulnerability Discussion

PKU2U is a peer-to-peer authentication protocol. This setting prevents online identities from authenticating to domain-joined systems. Authentication will be centrally managed with Windows user accounts.

Check

If the following registry value does not exist or is not configured as specified, this is a finding:

Registry Hive: HKEY_LOCAL_MACHINE
Registry Path: \SYSTEM\CurrentControlSet\Control\LSA\pku2u\

Value Name: AllowOnlineID

Type: REG_DWORD
Value: 0x00000000 (0)

Fix

Configure the policy value for Computer Configuration >> Windows Settings >> Security Settings >> Local Policies >> Security Options >> Network security: Allow PKU2U authentication requests to this computer to use online identities to "Disabled".