Runas

runas can be used to run a program as a different user, but it requires GUI access as it pops up a password prompt:

PS C:\Users\steve> runas /user:backupadmin cmd
Enter the password for backupadmin:
Attempting to start cmd as user "CLIENTWK220\backupadmin" ...

If we try to use runas as a newly-created user it won't work, because the user has to logged in at least once for the following reasons:

• User profile is not created yet: when we create a new user and add them to the Administrators group, Windows does not create a user profile for that user until the first login. Some privileges (especially file access and UAC-related permissions) rely on the presence of a user profile in C:\Users\<user>.

• Group membership changes require a re-login: even though the user was added to the Administrators group, it wasn’t immediately effective for existing sessions. Windows applies group membership changes only at login—so logging in once ensures the system recognizes the new user as an administrator.

• Access tokens are not updated: when a user logs in, Windows creates an access token containing their group memberships and privileges. If the new user was created mid-session, existing tokens wouldn’t reflect the new privileges until that user logs in.