North Korean hackers have recently pulled off one of the biggest cryptocurrency hacks of all time. Axie Infinity, a popular NFT video game that allows users to earn money as they play, announced in a blog post that they were the victims of a cyberattack on March 29 that saw the loss of 173,600 Ethereum and 25.5 million USDC, a digital stable coin that is pegged to the US dollar. 

According to the FBI, around $620 million worth of crypto was swiped in the attack. 

“The FBI, in coordination with Treasury and other U.S. government partners, will continue to expose and combat the [Democratic People's Republic of Korea's] use of illicit activities – including cybercrime and cryptocurrency theft – to generate revenue for the regime,” the FBI said in a recent statement.

The US treasury also expanded their sanctions list, adding the cryptocurrency address linked to Pyongyang that was used in the hack of Axie Infinity.

The hackers managed to breach the so-called Ronin Network bridge, an Ethereum side chain that allows players to exchange the digital coins they earn in the online video game Axie Infinity.

The FBI is putting the blame on APT38 and the Lazarus Group, a group of unknown cybercriminals who operate on behalf of the North Korean state. 

You may remember the Lazarus Group from the notorious Sony Pictures hack in 2014, in which hackers acquired the personal information of thousands of Sony employees. The hack also requested Sony withdraw its then-upcoming film The Interview, a comedy film starring James Franco and Seth Rogen about a plot to assassinate North Korean leader Kim Jong-un.

Little is known about the group, but they have been linked to a number of high-profile cyber attacks. Another infamous attack saw the North Korean hackers attempting to steal up to $1 billion from the national bank of Bangladesh via the SWIFT international payment network. Although the hackers came close to succeeding, the plan was ultimately foiled when the number of unusual requests raised suspicions at other banks. 

North Korea is one of the few nations that use state-backed hackers purely for monetary gain as a means to bolster the country’s revenue. A 2020 US military report says North Korea's hacker army has around 6,000 personnel, with operatives also working out of other countries, including Belarus, China, India, Malaysia, and Russia. It's estimated that North Korean hackers took off with at least $400 million worth of digital assets in at least seven online heists on cryptocurrency platforms in 2021.