These are the most feared hacker groups in the world

Jon Woo/Reuters

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.

"Advanced persistent threat" actors are frequently discussed as a hot topic among cybersecurity experts, political leaders, and white hat hackers.

Larry Downing/Reuters

It's the best way to define the hackers who burrow into networks and maintain "persistence" — a connection that can't be stopped simply by software updates or rebooting a computer.

Facebook

APTs vary in their methods of gaining access. Some use targeted email phishing campaigns that install malicious software onto a victim's machine, while other, more advanced groups will use "zero-day" exploits.

Paul Szoldra/Tech Insider

See the rest of the story at Business Insider