On a number of occasions I was working on the stand next to an ElAl aircraft ... the one that used to get parked on a remote stand (because they don't fly on Saturday?).
The only security (as such) was a single Group4 person wandering around underneath the aircraft, and another one trying to keep warm (or sleeping?) in a car which was parked at the head of the stand.
The aircraft doors were fully closed, and had 'tamper evident' tape across them.
That's not to say that there wasn't somebody inside the aircraft ...