Years back, I remember watching the Wargames scene where the computer was trying to "guess a passcode". Which it was doing remotely. Determining one digit at a time.

https://www.youtube.com/watch?v=tGNBdjVO04Y

https://www.youtube.com/watch?v=F7qOV8xonfY

I said, "This is completely ridiculous. That's not how any kind of real world authentication system works." Dramatic, yes. Realistic? No, never happen.

Some years later, there was a severe remote exploit for the filesharing feature for Windows 95 and 98 systems. Not only had the Microsoft person who designed the thing stored the password to a share in plaintext instead of hashing it, which would have precluded this from working, but there was also a bug where the server's authentication system could be sent a malformed message and only validated as many bytes of the password as had been specified in the authentication message. Someone promptly went out and wrote an exploit to brute-force access to a share by just asking it to only validate the first byte, try each, get in in at most 256 tries. I look at that and say "yeah, but it also exposes the next byte of the password itself, and those probably persist even after the thing is patched, not to mention the potential for credentials reuse for other things". I go modify Samba's smbclient to iterate through the thing, extract the password one byte at a time. I message a buddy who has a Windows 98 machine on the network, "hey, can I break into your machine for a sec?" He comes up "Uh, okay. What are you up to, tal?"

I fire it up and we're sitting there watching his password be printed on my Linux box's screen, one letter at a time. I said, "This is exactly like that scene in Wargames that I said could never, ever happen in real life, was just Hollywood. Guess that showed me." He says, "fucking Microsoft".

Honourable mention is NCIS Dual keyboard
https://www.youtube.com/watch?v=u8qgehH3kEQ

Top hacking scene of all time!

That's the gold standard for hacking, by far. But this also deserves a mention for pushing the bounds of technology, way ahead of it's time: https://youtu.be/fQGbXmkSArs

Cute Asian girl with green hair and a side ponytail: "I'm in!"

Six keystrokes later: "Ok I pulled up the floor plans to the building, disabled the cameras and unlocked all the doors."

that's a lot of cuts

One man's Linux is another man's OS/2.