If it's a computer, then it's vulnerable. Period.
A Cracker or Playful Hacker can cause unlimited harm/mischief in the TV world because any computer, or any device with a CPU as a component—or even with a few strands of copper wire in it—is connected to the Internet and thus becomes easily accessible and subvertible to the character's hacking skill. Everything from NORAD to the engine computer on [...] [tvtropes.org]