In recent months, experts and officials say North Korea has been "mining" bitcoin, demanding it as ransom payment and outright stealing the digital currency.
"It is a fact that North Korea has been attacking virtual currency exchanges," said Lee Dong-geun, a director with South Korea's state-run Korea Internet and Security Agency. "We don't know how much North Korea has stolen so far, but we do know that the police have confirmed the regime's hacking attempts."
North Korean hackers targeted four different exchanges that trade bitcoin and other digital currencies in South Korea in July and August, sending malicious emails to employees, according to police.
Bitcoin is a type of cryptocurrency that lives on computer servers. The virtual coins are "mined" by complex algorithms and recorded in a digital ledger.
Experts say it's unclear how much bitcoin and other cryptocurrencies North Korea has amassed.
"It's reasonable to assume some -- and the value is increasing significantly at the moment," said Bryce Boland, Singapore-based chief technology officer with cybersecurity firm FireEye.
Source: (http://money.cnn.com/2017/12/12/technology/north-korea-bitcoin-hoard/index.html)