North Korea is one of the world's poorest and most isolated countries, and yet it still has one of the most formidable – and dangerous – hacking networks on the planet. The Lazarus Group has targeted major international companies, stolen millions from banks and even shut down hospital departments. Investigative journalist Geoff White's forthcoming book "The Lazarus Heist" recounts how these networks emerged and the growing threat they pose today. He joined us for Perspective.