One of the world’s biggest bitcoin exchanges has been hacked

One of the largest bitcoin exchanges in the world has been hacked and 30,000 customers’ data has been compromised, according to a report from Yonhap News.

Bithumb is based in South Korea, and the country’s internet watchdog Internet & Security Agency is investigating after some customers say they lost money in the attack.

Bithumb did not immediately respond to Business Insider’s request for comment, though it reportedly says that users’ passwords were not stolen.

It’s one of the busiest exchanges in the world. On Tuesday, Motherboard reported that it was the fourth largest globally in terms of volumes of all cryptocurrencies traded daily; by Wednesday it had jumped to first place.

In a statement, Bithumb said (via cryptocurrency news site BraveNewCoin) that it was an employee computer that was compromised, rather than its core servers:

"The employee PC, not the head office server, was hacked. Personal information such as mobile phone and email address of some users were leaked. However, some customers were found to have been stolen from because of the disposable password used in electronic financial transactions."

BraveNewCoin reports that "billions" of won has been stolen. For context, one billion won is equal to around $870,000, or £670,000. As such, it is markedly smaller than some previous hacks of bitcoin exchanges, such as the now-infamous Mt. Gox, where $460 million (at then-current prices) in bitcoin disappeared in 2014. Some Bithumb users were reportedly victims of "phishing," where someone phoned them up saying they worked for Bithumb and scammed them out of funds.

The incident underscores the fact that it is not just investors and digital currency enthusiasts who are excited by the current surge of interest in cryptocurrencies. Criminals are also eyeing up businesses that hold bitcoin and its sister currencies, and no-one can promise absolute security.

There has been a wild surge of interest in Bitcoin, Ethereum, and other digital currencies over the last month, with prices surging to all-time highs. Bitcoin is currently worth $2,578 per coin, with a total global market cap of $42 billion, while Ethereum trades for $263 with a market cap of $24 billion, according to data from CoinDesk.