How to Launder $500 Million in Digital Currency

Early Friday morning in Tokyo, hackers broke into a cryptocurrency exchange called Coincheck Inc. and made off with nearly $500 million in digital tokens. It’s one of the biggest heists in history, with the exchange losing more than 500 million of the somewhat obscure NEM coins. The hack has raised questions about security of cryptocurrencies around the world.

Coincheck hasn’t disclosed how their system was breached beyond saying that it wasn’t an inside job. The company did own up to a security lapse that allowed the thief to seize such a large sum: It kept customer assets in what’s known as a hot wallet, which is connected to external networks. Exchanges generally try to keep a majority of customer deposits in cold wallets, which aren’t connected to the outside world and thus are less vulnerable to hacks. Coincheck also lacked multi-signature security, a measure requiring multiple sign-offs before funds can be moved.