> Sounds hard to believe. What kind of code would that be?
Device drivers, compilers, and some embedded systems come to mind immediately, there are plenty of others out there. I've worked on a lots of software where the only inputs were physical and sensor based, and the only outputs were to the screen. Device didn't even physically have network equipment.
I hope you're joking but I suspect you're not. Device drivers have the highest level of privileged access in many operating systems and code quality for drivers is so uniformly lousy (certain large vendors whose names begin with "N", "A", and particularly "Q", I'm looking at you) that attempting to break the drivers would be among the first things I'd consider if I were trying to root a device.
There are few things where security doesn't matter. But they are extremely rare. The situations where programmers think their code isn't security sensitive are probably vastly more common.