They spent nearly a year mapping the bank's network, studying how the systems work together, hunting for the bank's connection to something called SWIFT.

SWIFT is the mechanism in which banks all over the world transfer money, but SWIFT itself doesn't transfer the money.

SWIFT is really a communications protocol, like a chat messaging system that allows banks to send messages to each other to say, "Hey, I wanna transfer 2 million from this account to this account." The banks then do that debiting and crediting.

SWIFT doesn't do that.

And so that SWIFT system is really based on trust.

So if I'm logged into my SWIFT account and I send you a message and say, "Please debit 2 million," you trust that what I'm doing is accurate and the truth, and I have vetted, for example, the company who's deciding to debit those amounts.

Most banks would have a separate room that would have their SWIFT terminal, so it's just a computer that had the SWIFT software on it, that messaging software.

It exposed glaring vulnerabilities in the global financial system, and it proved once again that we underestimate North Korea's digital ingenuity at our own cost.