In February 2017, an attack on the South Korean cryptocurrency exchange Bithumb saw some $7 million in bitcoin and ethereum stolen, although the theft wasn’t actually detected until June. Now, there are signs that the criminals responsible are based in North Korea.

Bithumb is the largest cryptocurrency exchange in the country, and indeed one of the top five worldwide. It’s being theorized that North Korea may have carried out the attack in response to financial sanctions put in place as a result of its development of nuclear weaponry, according to a report from BBC News.

Bitcoin has had a record-breaking year, and is currently approaching the $20,000 mark – something that few would have expected would happen so quickly, given the fact that it hadn’t hit $1,000 as of the beginning of 2017. This is especially pertinent to this theft, as it’s thought that the funds that would have been worth around $7 million at the time would now be valued at around $82.7 million.

Digital currency wasn’t the only thing that was stolen in the attack. The hackers also made off with the personal information of over 30,000 users, and apparently demanded a ransom of $5.5 million from the proprietors of Bithumb to ensure that they would delete these records.

South Korean authorities have since determined that the company did not do enough to protect its users, given that their private data was unencrypted, according to a report from Chosun. The government imposed $55,000 in fines on the firm on December 13.

Up until now, digital currencies have not come under scrutiny from South Korea’s financial authorities, but that’s all set to change in the wake of this high-profile situation. This attack could serve as a warning of things to come elsewhere in the world, as criminal activity associated with cryptocurrency seems to be growing in prominence, and various governments seem eager to nip it in the bud.

Bitcoin mining marketplace Nicehash was recently hit by an attack that saw almost $64 million worth of cryptocurrency go missing. As values continue to rise, this kind of crime will only become more lucrative, so we can perhaps expect to see more situations of this nature.