I helped catch Joy Seven. I'm still chasing Four. You've likely heard that Seven doesn't enjoy talking about her past? They don't say why? She has a brand shiny new conscience, and hundreds of ghosts lingering in her memory chips.
Seven was a pirate. There are a bunch of ways to kill a biological starship crew without damaging an android. Seven knows them all. She has used most of them. Replicate toxin and transport it through the ship. Play games with life support or the inertial compensator field. Disease is a good one. Chose the right bug, and the crew ends up begging the pirate to take over their ship.
Norman One took the old Enterprise with his bare fists. Since then, the androids have learned about martial arts. Seven can fake fingerprints, retina prints, and voice prints. She is an unimaginative hacker, but her network port is faster than any human can type. She has a long list of tricks to try, and she is patient about trying them all. Should she ever get a sysop level access key, and copy herself into a computer core, I'd purge everything twice, reload the operating system from read only masters, and still not feel sure I'd caught her.
Savik claims there is one proper way to get her out of a computer system. Give her an order to come out. He trusts her. I wish I could trust her that much. She would make one great security second if I could. But for someone like her to copy into a ship's core, she wouldn't own the ship, she would be the ship. If I had power like that, I'm not sure I'd come out again. I just can't see it of Seven, either.