Windows Server 2019 must be configured to audit Logon/Logoff - Group Membership successes.

Maintaining an audit trail of system activity logs can help identify configuration errors, troubleshoot service disruptions, and analyze compromises that have occurred, as well as detect attacks. Audit logs are necessary to provide a trail of evidence in case the system or network is compromised. Collecting this data is essential for analyzing the security of information assets and detecting signs of suspicious and unexpected behavior.

Audit Group Membership records information related to the group membership of a user's logon token.

Security Option "Audit: Force audit policy subcategory settings (Windows Vista or later) to override audit policy category settings" must be set to "Enabled" (WN19-SO-000050) for the detailed auditing subcategories to be effective.

Use the "AuditPol" tool to review the current Audit Policy configuration:

Open "PowerShell" or a "Command Prompt" with elevated privileges ("Run as administrator").

Enter "AuditPol /get /category:*"

Compare the "AuditPol" settings with the following:

If the system does not audit the following, this is a finding.

Logon/Logoff >> Group Membership - Success

Configure the policy value for Computer Configuration >> Windows Settings >> Advanced Audit Policy Configuration >> System Audit Policies >> Logon/Logoff >> "Audit Group Membership" with "Success" selected.