How is rear bumper supposed to be attached?

[spdrun]

I went to move my car this morning, and I found out that some numbskull had hit my car and the rear bumper was hanging off halfway. As in it had detached from the strut that normally supports it. There seems to be a rubber pad at the end of the strut, but it's not clear how the bumper was supposed to attach to it.

Was it originally glued?

If I find out who did this (I won't), I'd like to rearrange their face in a similar manner with a large breaker bar.