A DeFi participant suffered a devastating $563K loss during fund withdrawal from major lending protocols Aave and Compound. The incident stemmed from a critical mistake: approving an unknown token that granted an attacker complete transfer authority over the user's aEthUSDT holdings. Once the malicious permission was granted, the attacker-controlled address moved swiftly to drain the assets before the victim could revoke the approval. This incident underscores a persistent vulnerability in DeFi workflows—permission management remains a major attack surface. Users interacting with liquidity protocols must exercise extreme caution when signing token approvals, especially for unfamiliar contracts. Always verify smart contract addresses before granting transfer permissions, and consider using allowance limits rather than unlimited approvals whenever possible. The speed at which attackers capitalize on these permissions makes prevention far more effective than attempting recovery.