Re: A decade of poor configuration
Not just the late '80s, when xhost + was still a default. Right into the '90s you could - and inevitably sometimes did - make someone else's computer burst into song, tell a joke, admonish the user, or just fart. You could also trivially run your prank from another computer again to leave a false trail in case someone investigated: a local area version of the CIA routing an attack to come from China or Russia.
But we did it for laughs, and drew the line at actually damaging anyone's work.
Oh, and this wasn't even a university. Though it was a research institute funded by (many) governments, so not quite the corporate world.