✅ Master Smart Contract Security
Understand vulnerabilities, secure patterns, and audit readiness
Protect your dApp from common vulnerabilities
Your Progress
0 / 5 completed🎓 Module Summary
🛡️ What You Learned
1. Why Security is Existential
Smart contracts are immutable and hold billions in assets. One bug = permanent vulnerability. The DAO ($60M), Parity ($150M), Poly Network ($611M), Ronin ($625M) weren't theoretical—they were production disasters. Security isn't optional, it's existential.
2. Common Vulnerabilities
Reentrancy (recursive calls before state update), integer overflow/underflow (arithmetic wrapping), access control bugs (missing permission checks), front-running (MEV bots), timestamp dependence, unchecked returns, unbounded loops, delegatecall risks, oracle manipulation, DoS attacks.
3. Secure Patterns
Checks-effects-interactions (validate → update state → external calls), pull-over-push payments (users withdraw, don't push to them), Ownable/RBAC (access control), ReentrancyGuard (prevent nested calls), pausable (emergency stop), time locks (delay sensitive operations), storage gaps (safe upgrades).
4. Testing Pyramid
4 layers—Unit tests (70-80% coverage, fast feedback), Integration tests (multi-contract flows), Fuzz testing (random inputs find edge cases), Formal verification (mathematical proofs, 100% certainty). Each layer catches different bug types.
5. Professional Auditing
Top protocols hire 2-3 audit firms ($50k-200k each), run bug bounties ($10k-$1M+ rewards), and achieve 90%+ test coverage before mainnet. Trail of Bits, OpenZeppelin, Certora, Consensys are industry standards. Code4rena for competitive audits.
💡 Key Insights
- •Assume Adversarial: Every input is an attack vector. Every external contract is malicious. Code defensively.
- •Defense in Depth: Multiple security layers. If one fails, others prevent exploit. Checks + ReentrancyGuard + pull payments.
- •Simplicity > Cleverness: Simple code has fewer bugs. Avoid gas optimizations that sacrifice readability.
- •Test Everything: 90%+ coverage isn't optional for production. Unit + integration + fuzz + formal verification.
- •Never Skip Audits: Even experienced teams miss bugs. External eyes find vulnerabilities you can't see. 2-3 audits standard.
🚀 Production Checklist
🎯 Knowledge Check
Test your understanding of smart contract security with this 5-question quiz. Each question includes detailed explanations.