Where does "attacker" come into it? That's not mentioned at all by the OP. Of course, if you have an attacker on your webserver that's able to write files, you're likely to be in deep shit anyway.

But feel free to add to add as many random numbers as you want to your pid so you no longer have to bother about this attacker that has gained access to your system.

Now excuse me, I have to hide that box of chocolates under my car seat, lest someone breaking in my car gets easy access to my stash.