Arcadia Finance exploited

Arcadia Finance is a defi margin trading protocol that launched on Ethereum and the Optimism Ethereum layer 2 protocol in March 2023. On July 9, an attacker used a flash loan to drain liquidity pools in the lending portion of the project, resulting in a total loss to the project of around 160 ETH and $163,000 in stablecoins for a total loss of almost $460,000.

The Arcadia Finance team paused related smart contracts to prevent further attacks, and began working with various crypto security projects to investigate the attack. They also sent on-chain messages to the attacker, threatening law enforcement action and suggesting they "return 90% of the funds... and walk away".