Within a few short years, North Korea’s hackers have gone from being a niche phenomenon to a prime cyber force that’s often first in line when researchers try to identify who may be responsible for major digital sabotage. 

But figuring out which of the many groups really launched an attack is a tricky business: The best hackers don’t just know how to break into vulnerable computers, they also often try to imitate each other in style and process, planting “false flags” that aim to mislead security researchers and foil their efforts to identify who