DeFi hacks might seem like a variety of attack methods on the surface: Reentrancy, private key leaks, oracle manipulation, flash loans, cross-chain bridge vulnerabilities, phishing for signatures, unlimited approvals, front-end hijacking... But it really boils down to 5 key areas: 1. Permission Design Who can move funds, upgrade contracts, or change parameters. 2. Contract Correctness Can the code maintain asset conservation under extreme conditions? 3. External Dependencies Oracles, bridges, front-ends, RPCs, third-party contracts—any link could become an entry point. 4. Private Keys & Operations Many so-called "contract hacks" are essentially failures in off-chain control. 5. Incentives & Governance Does the attack yield more profit than its cost? Can governance be manipulated through vote borrowing, buying, or other means? So the core of DeFi security isn’t just “doing one more audit.” It’s about reducing the probability that any single point of failure directly leads to a loss of funds. DeFi hack risk = Asset exposure scale × Permission centralization × Contract complexity × External dependency vulnerability × Operational error rate ÷ Defense redundancy True defense is making it so that even if an attacker finds one layer of vulnerability, it’s still extremely difficult to turn it into withdrawable profit.