According to the summary, the attacker took out a flash loan on lending platform Aave which enabled them to amass a large amount of Beanstalk’s native governance token, Stalk. With the voting power granted by these Stalk tokens, the attacker was able to quickly pass a malicious governance proposal that drained protocol funds into a private Ethereum wallet.
Source: https://www.coindesk.com/tech/2022/04/17/attacker-drains-182m-from-beanstalk-stablecoin-protocol/?utm_medium=referral&utm_source=rss&utm_campaign=headlines