Can it teach me how to break into computers and steal stuff or write a virus?
No you won’t learn how to break into computers and steal stuff or how to write a virus. In fact, some of the people who attend MacHack are the ones who write the anti-viral software. The hacks that come out of MacHack are those that do clever, amusing or useful things to the system software. Hacks which can do damage to data, networks etc. are not welcome at the conference. Of course, the nefarious programmer can always use information to further the cause of evil, but this is strongly discouraged.