FutureSwap protocol on the Arbitrum chain was subjected to a flash loan attack, resulting in an asset loss of approximately 394,000 USDC.e. The attacker manipulated the internal account balances of the protocol to bypass checks and execute unsecured withdrawals. Fortunately, the Forta Firewall risk alert system detected the anomaly in time, which could have prevented this incident. This case serves as a reminder to DeFi users to pay attention to protocol security measures.