North Korea-linked hackers thought to have stolen $100 million in cryptocurrency heist

North Korean hackers have been thought to have stolen $100 million in cryptocurrencies from a US company last week, as the regime steps up its efforts to secure funding for its nuclear and ballistic missile programmes.

Three digital investigative firms concluded that assets were stolen from the Horizon Bridge, a service operated by the Harmony network that allows them to be transferred to other blockchains.

Since the heist suggests that they may be linked to North Korea, the hackers are believed to be among the most prolific cyber-attackers.

Chainalysis, a blockchain firm working with Harmony to investigate the attack, said on Tuesday that the style of attack and high velocity of structured payments to a mixer used to obscure the origin of funds is similar to previous attacks that were attributed to North Korea-linked actors.

Other investigators were echoed that conclusion.

Nick Carlsen is a former FBI analyst who is now investigating North Korea's heists for TRM Labs, a US-based firm that looks like a North Korean hack based on transaction behavior.

There are strong indications that North Korea's Lazarus Group may be responsible for the theft, based on the nature of the hack and the subsequent laundering of the stolen funds, another firm, Elliptic, said in a report on Thursday.

The report said that the thief is trying to break the transaction trail back to the original theft. It makes it easier to cash out the funds at an exchange. US officials say Lazarus is controlled by the Reconnaissance General Bureau, North Korea's primary intelligence organisation. It was accused of being involved in the WannaCry ransomware attacks, hacks of international banks and customer accounts, and 2014 cyber-attacks against Sony Pictures Entertainment.

Last week s attack would be the eighth this year involving $1 billion in stolen funds that could be confidently attributed to North Korea, Chainalysis said. The thefts account for 60% of all stolen funds this year, it added.

In recent years, the regime has poured resources into stealing cryptocurrencies, and was responsible for one of the largest heists on record in March, in which almost $615 million was stolen, according to the US Treasury.

North Korea s ability to cash in on its stolen assets could be hampered by a recent plummet in cryptocurrencies markets that are thought to have wiped out millions of dollars of the regime's funds.

According to the Korea Institute for Defence Analyses in Seoul, if the crash continues, experts believe that Pyongyang could use other ways to fund a missile programme that has cost $620 m so far this year.