ZwOpenThreadTokenEx

NTSTATUS __stdcall ZwOpenThreadTokenEx(
        PVOID ThreadHandle,
        UINT64 DesiredAccess,
        UINT8 OpenAsSelf,
        UINT64 HandleAttributes,
        PVOID *TokenHandle){
  NTSTATUS result; 
  _disable();
  __readeflags();
  KiServiceInternal();
  return result;
}

Referenced by:

BiAdjustPrivilege
RtlpIsAppContainer
RtlpOpenThreadToken
SysCtxRegOpenCurrentUserKey