My favorite feat of IT wizardry in a movie is in Independence Day where Jeff Goldblum's character hacks into the onboard computer of an alien spaceship using nothing but his MacBook. Of course, entire generations of scientists have failed to get into that computer but the wizz just does it overnight. Does it even use a binary system? Does it use quantum computing? What security features do alien computers have? No matter.
Better yet, he manages to coax the computer on the alien space station (which he has never had physical access to!) into letting them dock without raising the alarm.
But the icing on the cake is the virus he manages to inject into this previously unknown IT system which not only grants him full access but also plays back a laughing skull animation on an operator console he has never seen, not even while developing his virus.
Ludicrous.