_Follow along with the video lesson:_ --- ### Exercises The life of a security researcher is one of constant growth and learning. If you've completed this section and you're looking for the next steps, here's where you can start: Exercises: 1. [Damn Vulnerable DeFi Challenges](https://www.damnvulnerabledefi.xyz/) 1, 2, 4 2. Write a tweet thread about an interesting [finding from Solodit](https://solodit.xyz/) 3. Tweet about how you finished the hardest audit yet! 4. Read about more historic attacks: - [Signature Replay](https://solodit.xyz/issues/router-signatures-can-be-replayed-when-executing-messages-on-the-destination-domain-spearbit-connext-pdf) - [Merkle tree signature issues](https://solodit.xyz/issues/m-14-merkle-tree-related-contracts-vulnerable-to-cross-chain-replay-attacks-code4rena-factorydao-factorydao-contest-git) - [Polygon Double Spend](https://medium.com/immunefi/polygon-double-spend-bug-fix-postmortem-2m-bounty-5a1db09db7f1) - [Nomad Bridge Hack](https://medium.com/immunefi/hack-analysis-nomad-bridge-august-2022-5aa63d53814a) ## Wrap Up In the section ahead, we'll dive into what MEV is, why it matters, and how we can fortify our contracts against potential issues stemming from it. Now, go ahead and take that well-deserved break, grab that cup of coffee or make that gym run. Come back refreshed, because we've got a lot more in store for you! 💰💰💰💰💰💰💰💰💰💰💰💰💰💰💰💰💰💰💰💰💰💰💰💰💰💰 ### Section 7 NFT Challenge: [**Tell Vitalik Hi (Arb)**](https://arbiscan.io/address/0xB855afC44095225105329a7416D55d0A780fc39d#code) [**Tell Vitalik Hi (Sepolia)**](https://sepolia.etherscan.io/address/0x33ee14fb8816c92fe401165330bbe29706942183) 💰💰💰💰💰💰💰💰💰💰💰💰💰💰💰💰💰💰💰💰💰💰💰💰💰💰