How I Hacked McDonald's (Their Security Contact Was Harder to Find Than Their Secret Sauce Recipe)

I've posted this on HN too, but the author seems a bit... immature in their handling of things? Using a friend's login to pentest stuff (causing the friend to get fired, rightfully so), defacing internal applications, creating bogus orders...

They're cocky and they don't fully seem to grasp yet how their behavior works against them.