I heard that before too. If its true then Its pretty worrying.
there is nothing "new" to worry about here!
people have always been trying to hack exchanges and everything that can give them "free money", saying it is North Korea now that is trying to do it, is just conspiracy theories by some random website that wants some traffic so they release some click-bait article.
the exchanges are either safe and won't get hacked that easily or they are idiots who don't know what a cold storage and security is and will get hacked easily. or they just simply scam you and run away but say they were hacked