Title

Windows Server 2019 Impersonate a client after authentication user right must only be assigned to Administrators, Service, Local Service, and Network Service. (Cat II impact)

Discussion

Inappropriate granting of user rights can provide system, administrative, and other high-level capabilities. The "Impersonate a client after authentication" user right allows a program to impersonate another user or account to run on their behalf. An attacker could use this to elevate privileges.

Check Content

Verify the effective setting in Local Group Policy Editor. Run "gpedit.msc". Navigate to Local Computer Policy >> Computer Configuration >> Windows Settings >> Security Settings >> Local Policies >> User Rights Assignment. If any accounts or groups other than the following are granted the "Impersonate a client after authentication" user right, this is a finding: - Administrators - Service - Local Service - Network Service For server core installations, run the following command: Secedit /Export /Areas User_Rights /cfg c:\path\filename.txt Review the text file. If any SIDs other than the following are granted the "SeImpersonatePrivilege" user right, this is a finding: S-1-5-32-544 (Administrators) S-1-5-6 (Service) S-1-5-19 (Local Service) S-1-5-20 (Network Service) If an application requires this user right, this would not be a finding. Vendor documentation must support the requirement for having the user right. The requirement must be documented with the ISSO. The application account must meet requirements for application account passwords, such as length (WN19-00-000050) and required frequency of changes (WN19-00-000060).

Fix Text

Configure the policy value for Computer Configuration >> Windows Settings >> Security Settings >> Local Policies >> User Rights Assignment >> "Impersonate a client after authentication" to include only the following accounts or groups: - Administrators - Service - Local Service - Network Service

Additional Identifiers

Rule ID: SV-205760r877392_rule

Vulnerability ID: V-205760

Group Title: SRG-OS-000324-GPOS-00125

Expert Comments

CCIs tied to check.

Controls tied to check. These are derived from the CCIs shown above.