FullPowers is a Proof-of-Concept tool I made for automatically recovering the default privilege set of a service account including SeAssignPrimaryToken and SeImpersonate.
On Windows, some services executed as LOCAL SERVICE or NETWORK SERVICE are configured to run with a restricted set of privileges. Therefore, even if the service is compromised, you won’t get the golden impersonation privileges and privilege escalation to LOCAL SYSTEM should be more complicated. However, I found that, when you create a scheduled task, the new process created by the Task Scheduler Service has all the default privileges of the associated user account (except SeImpersonate). Therefore, with some token manipulations, you can spawn a new process with all the missing privileges.