Bitcoin's insane value makes it an attractive hacking target for cash-strapped North Korea

When you're a nation mostly barred from exporting your most valuable assets — gold, copper, silver, coal, and even seafood — getting hold of hard currency is a tricky problem.

North Korea, facing a wide range of UN sanctions on exports and trade, has turned to another asset class to try to keep the money flowing: cryptocurrencies.

According to a report by the security researcher FireEye, North Korean hackers have shown increasing interest in carrying out bitcoin attacks.

Cryptocurrency attacks linked to North Korea started in 2016, and they "marked a departure from previously observed activity of North Korean actors employing cyber espionage for traditional nation state activities," FireEye said. In other words, North Korea's hackers had swapped their usual cyberspying for theft.

Specifically, the hackers began targeting South Korean cryptocurrency exchanges. Since May this year, FireEye wrote, there have been three attacks alone, one of which has been successful. FireEye didn't name the exchange.

The hackers also compromised an English-language bitcoin news website in 2016, though again FireEye didn't say which.

And in April, hackers compromised four cryptocurrency wallets on Yapizon, a South Korean exchange, though FireEye said there wasn't a clear link to North Korea.

For the most part, hackers targeted victims with spear-phishing, a technique in which a hacker uses targeted emails to obtain someone's confidential information or data. The techniques and malware they used, including "Peachpit", had been linked to North Korea in earlier attacks.

Theres one good reason North Korea wants bitcoin

Bitcoin has increased 600% in value in the past year.

While bitcoin has suffered a drop in value over the past few days because of a cryptocurrency crackdown in China, overall it has massively increased in value.

And North Korea is already involved with other types of illicit currency smuggling, like counterfeiting foreign currency and gold smuggling.

If hackers manage to compromise an exchange — as opposed to a single wallet — they can move cryptocurrencies around and swap them for hard currencies like South Korean won or US dollars, the FireEye researchers wrote.

Another huge appeal for cryptocurrencies is that there's still very little regulation, though that's changing fast.

It "should be no surprise," the researchers wrote, "that cryptocurrencies, as an emerging asset class, are becoming a target of interest by a regime that operates in many ways like a criminal enterprise."

Tracking down the culprit of a cyberattack is generally difficult, and North Korea has generally denied any part in global cyberattacks, despite being linked to the devastating WannaCry ransomware attack in May.