Ethereum core developer Eric Connor revealed that a Maximal Extractable Value (MEV) bot received 584 ETH, worth over $1 million, from front running an incoming hack in the transaction mempool.

Several other significant MEV block rewards were recorded around the same time, with the recipients earning 345 ETH, 247 ETH and 51 ETH. The rewards stem from front running transactions sent by exploits that took place on Curve Finance’s liquidity pools on Sunday.

Notably, these MEV rewards are the largest recorded in the history of Ethereum, incidentally falling on the network’s eighth official year in existence.   

In order to earn these rewards, MEV bots reproduce and front run transactions by paying the block producers a significant amount of ETH to move their transactions up to the front of the line.

“They’re paying money that was stolen from victims as kickback bribes to Ethereum validators,” wrote one user on Twitter. 

While several market participants questioned the morality of block producers keeping these rewards that came from hacked funds, Connor opined that returning the funds is likely more complex than it appears on the surface, while noting it is “probably a legal grey area.”

Meanwhile, at least one MEV bot deployer has returned funds after front running a hacker’s transaction. Blockchain data shows that “c0ffeebabe.eth” returned 2,879 ETH worth $5.3 million to the Curve deployer contract.