The National Intelligence Service (NIS) told a parliamentary intelligence committee on February 5 that North Korean hackers have attacked cryptocurrency exchanges, according to Kim Byung-ki, a ruling Democratic Party legislator who participated in the committee's closed session.
This apparently led to tens of billions of won in digital cash being stolen from domestic platforms.
As a result of the breach, the Japanese exchange temporarily halted its operations.
Assuming the Coincheck hack was indeed carried out by North Korea, it would just be the latest example of the reclusive country attempting to generate revenue from cryptocurrency. It later announced a compensation policy created to return more than 260,000 users who were affected by the breach.
North Korea is no stranger to cryptocurrencies: The rogue regime has been accused of launching a global ransom attack to raise bitcoin, hacking South Korean exchanges, and mining crypto both within its borders and secretly on your computers.
Last month, Coincheck, one of Japan's biggest cryptocurrency exchanges, said it had about 58 billion yen ($530 million) worth of NEM virtual coins stolen and that it would return 46.3 billion yen to investors who had lost funds.
"It's a possibility that North Korea could be behind the theft", said the source, who had knowledge of Intelligence Committee proceedings.
North Korea also ran a near-record trade deficit of $1.96 billion with China in 2017, the NIS reportedly informed the National Assembly on Monday, owing to United Nations Security Council sanctions banning exports of goods including coal, marine products and garments.
North Korea has shown increasing interest in cryptocurrency over the a year ago, likely as a result of a number of factors including the sudden rise of value of numerous cryptocurrencies as well as stifling economic sanctions that have made it hard for the isolated nation to generate revenue.
South Korea's national spy agency told a parliamentary committee it was possible North Korean hackers broke into a cryptocurrency exchange in Japan to steal $520 million worth of digital coins, a person familiar with the matter said on Tuesday.