Something to keep in mind is that a lot of hacked systems may have may not noticed as such immediately because of the large number problems that are quickly traced back to human error. Most of the problems with computer systems have always been human errors (either in the design or maintenance of hardware or software.) Indeed, there have been so many human error problems, compared to obvious hacks of systems, that it is very difficult to find a good hack among all the problems cause by people's ineptitude.