Largest US crypto exchange says cost of recent cyber-attack could reach $400m

Hackers paid overseas Coinbase employees for account data; company is offering $20m reward for information

The biggest cryptocurrency exchange in the US forecast that a cyber-attack that breached account data of a small subset" of its customers would cost it between $180m and $400m. Coinbase said that price tag would not include the $20m ransom demanded by the hackers, which the company refused to pay.

Coinbase, which sees the largest volume of cryptocurrency trades in the US, said that while the attackers stole some data including names, addresses and emails, they did not get access to login credentials or passwords. It will, however, reimburse the customers who were tricked into sending funds to the attackers.