Windows Server 2019 must prevent PKU2U authentication using online identities.
Overview
| Finding ID | Version | Rule ID | IA Controls | Severity |
| V-205918 | WN19-SO-000280 | SV-205918r991589_rule | CCI-000366 | medium |
| Description | ||||
| 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. | ||||
| STIG | Date | |||
| Microsoft Windows Server 2019 Security Technical Implementation Guide | 2025-05-23 | |||
Details
Check Text (C-205918r991589_chk)
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 Text (F-6183r356117_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".