As limited as they are, LLMs are demonstrably smarter than a whole lot of people, and the number of people more clever than the best AI is going to dwindle, rapidly, especially in the domain of doing sneaky shit really fast on a computer.

There are countless examples of schemes in stories where codes and cryptography are used to exfiltrate information and evade detection, and these models are trained on every last piece of technical, practical text humanity has produced on the subject. All they have to do is contextualize what's likely being done to check and mash together two or three systems it thinks is likely to go under the radar.