Attack surface

Your attack surface is every way in. Every door, window, letterbox and cat flap.

The surprise is usually how many there are. Not just the website, but every login, every app plugged into another app, every password shared with a supplier, every account belonging to somebody who left last year and still works. It grows a little each time you add something new, and it almost never shrinks by itself, because tidying up is nobody's actual job.