NY time on Friday and was trading at $6,781.19 as of 11:43 a.m.in Hong Kong on Monday, bringing its year-to-date loss to 53 percent. It did not quantify the value, but local news outlet Yonhap News estimated that about 40 billion won (£27.8m) worth of virtual coins was stolen.
The hacking attack on Coinrail comes after Japan's cyrptocurrency exchange Coincheck was hacked earlier this year in a high-profile theft of its digital currency.
Without disclosing the exact amounts stolen, Coinrail revealed some of the stolen ERC-20 tokens, namely NPXS tokens from Pundi X, a payment project; ATC from Aston X, a decentralized document project and; NPER tokens from the namesake decentralized IP project.
Coinrail was mostly trading ERC20 tokens, according to CoinMarketCap. Popular cryptocurrency exchange, Bitfinex - infamous for its $68 million hack in 2016 - suffered a domain denial of service (DDoS) attack last week. "It is a minor player in the market and I can see how such small exchanges with lower standards on security level can be exposed to more risks", Kim Jin-Hwa, a representative at Korea Blockchain Industry Association.
South Korea is one of the biggest markets for trading in digital currencies but the boom in their popularity has forced the government to tighten regulations, following similar moves in other countries.
Coins other than Pundi X seem to have been transferred to a wallet at another decentralized cryptocurrency exchange, Etherdelta. "For the rest, we are investigating into it with an investigative agency, related exchanges and coin developers", it added.
Coinrail later said in a statement on its website that its system was hit by "cyber intrusion" on Sunday, causing a loss for about 30% of the coins traded on the exchange. The company wasn't immediately available for further comments.