Coinrail said in a statement on its website that it's reviewing its system due to hacking attempts. However, South Korean news outlet Yonhap News - via The Guardian - reported that some 40 billion won worth of digital coins were grabbed by the hackers; that's some £27.8m in real-world money. The Wall Street Journal reported Friday that United States investigators were demanding several bitcoin exchanges hand over trading data as part of a probe into potential manipulation of futures markets.
Coinrail did not specify the value of the currency that was taken in the attack at the weekend but said it was working with authorities and other coin developers to track down the culprits.
When the bitcoin price fell more than $1,000 and the cryptocurrency market cap shed more than $40 billion on "Bloody Sunday", many media commentators attributed the decline to a security breach at a small cryptocurrency exchange in South Korea.
Cryptocurrencies are still popular, especially with young investors.
South Korea has emerged as a hotbed for trading in virtual currencies over the a year ago.
"All assets of CoinRail, which have not been leaked, are moved to a cold wallet and are kept safe, and transactions and withdrawals will resume after stabilizing the service". Again that date might not seem very long ago, but in the wildly fluctuating world of cryptocurrency values, it's significant.
Korea Internet & Security Agency, now carrying out the investigation with police, said only four of the country's largest exchanges are subject to the Information Security Management System certification (ISMS) requirement.
"Coinrail, as of June this year, hasn't been certified with the ISMS, as it isn't mandatory (for the organisation to do so)", the local regulator said in a statement. Coinrail only said that it was cooperating with investigators and other exchanges to try and track down the perpetrators and recover the money.