Building on Sui is exciting — its object-centric model opens up new design patterns and faster parallelism. But ⚠️ new models = new mistakes. Ownership bugs, escrow leaks, or careless admin keys can cause costly losses.

This guide gives you a step-by-step security checklist 📝 plus a practical marketplace example to show how to avoid the most common pitfalls.

✅ 1) The Sui Security Checklist 1. 🔑 Least Privilege • Don’t rely on a single global “admin key.” • Use capability objects for authority. • Guard critical admin powers with multisig or on-chain governance. 2. ⚖️ Atomic Escrow Transfers • Always escrow assets inside dedicated Listing objects. • Use Programmable Transaction Blocks (PTBs) for atomic swaps → prevents front-running and double spends. 3. 🛡️ Validate All Inputs • In Move, check vector lengths, bounds, and constraints. • Validate deserialization and reject malformed objects. • Never assume input safety just because the object exists on-chain. 4. 🧪 Test & Fuzz Aggressively • Write negative tests: invalid inputs, concurrent updates, gas exhaustion. • Add fuzzing for unexpected transaction flows. • Automate in CI to catch regressions early. 5. 🔐 Key Management • Store admin keys in hardware wallets. • Use multisig for governance actions. • Rotate keys when team members leave. 6. 👀 Audits & Incentives • Get critical Move modules audited. • Launch a bug bounty program for community testing. • Remember: external eyes catch what you miss.

🏪 2) Example in Practice: A Safe Marketplace

Here’s how to apply the checklist in a marketplace dApp: • Escrow NFTs safely: Seller moves the NFT into a Listing object. The marketplace contract cannot take funds without seller’s approval. • Handle royalties correctly: Compute royalties inside the PTB, ensuring correct fee splitting (watch out for rounding!). • Reentrancy? Not here: Move’s resource model prevents copying/reentrancy by design. Still, test all flows to ensure no logical loopholes.

📚 Sources & Further Reading • Sui Docs: Concepts & Transactions • Sui Whitepaper (object-centric model) • Mysten Labs TypeScript SDK Docs • Move Book • Sui GitHub Repo

✨ Takeaway: On Sui, security is less about EVM-style reentrancy bugs and more about ownership, authority, and atomicity. If you follow the checklist, you’ll reduce your attack surface dramatically while keeping user assets safe.