These are the most feared hacker groups in the world

The most feared hacker groups are what cybersecurity professionals refer to as "advanced persistent threat" actors.

Unlike your average hacker breaching a server for curiosity or activism, or criminal gangs armed with ransomware and interested only in money, APTs backed by nation-states usually are among the very best.

And most of the time, they are interested in just one thing: Stealing secrets.

Well, that, and not getting caught.