Sandy Kronenberg has started two companies from nothing. The second time, on a credit card he wasn't sure his dad would let him keep using.

He's also spent the last three years watching AI turn old school fraud into something faster and harder to catch. A finance worker in Hong Kong wired close to $30 million after 17 video calls with someone who looked and sounded exactly like his CFO. He wasn't.

Sandy built a company called Netarx to catch that kind of thing before it happens, a tool that puts a traffic light on your screen during any call to tell you if the person on the other end is real. Along the way he's run into North Korean operatives applying for remote jobs, water utilities with China already inside their networks, and a theory he calls the biggest heist of the century. Not the kind anyone's going to jail for.

What we ...