Axie Infinity was the prime example of crypto gaming last year, when its play-to-earn formula helped it reach up to 2.7 million daily active users last November. But that all came crashing down in March, when hackers stole $ 625 million from the Ethereum-linked Ronin sidechain powering the game. Now, it turns out, the source of that hack came from an unlikely source: A fake job offer from LinkedIn. 

As The Block reports (via The Verge) based on two sources, the hackers infiltrated Axie Infinity owner Sky Mavin's network by sending a spyware-filled PDF to one employee. That person thought they were accepting a high-paying job from another firm, but it turns out that company never existed. According to the US government, North Korean hacker group Lazarus was behind the attack. 

“Employees are under constant advanced spear-phishing attacks on various social channels and one employee was compromised," Sky Mavis noted in a post-mortem blog post following the hack. "This employee no longer works at Sky Mavis. The attacker managed to leverage that access to penetrate Sky Mavis IT infrastructure and gain access to the validator nodes.”

Axie Infinityspun back up last week, and it's still relying on the Ronin sidechain, albeit with stricter security measures. The company raised its validator nodes to 11 in April, up from 9 previously, which makes it more difficult for attackers to gain control of the network. (Lazarus gained access to 5 nodes to achieve its hack, including one from the Axie DAO [Decentralized Autonomous Organization].) And it's also implementing a "circuit-breaker" system to flag large withdrawals. 

While this hack was clearly meticulously planned and required a significant amount of technical skill, it ultimately hung on a classic vulnerability: social engineering. 

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