Advanced DeFi Security Workshop: ENS Verification, Transaction Simulation, and Approval Auditing

The November 22, 2025 compromise of Aerodrome Finance’s DNS infrastructure demonstrated that sophisticated DeFi users face threats that basic security checklists cannot address. While beginners worry about obvious phishing emails and seed phrase exposure, experienced practitioners must defend against attacks that exploit the precise intersection of web2 infrastructure and web3 interaction patterns. This advanced walkthrough covers three critical defensive techniques that go beyond standard security advice: ENS domain verification, transaction simulation pipelines, and systematic approval auditing.

The Objective

After completing this tutorial, you will be able to independently verify ENS-based access points for any DeFi protocol, construct a local transaction simulation environment that catches malicious payloads before they reach your wallet, and implement an automated approval auditing workflow that continuously monitors your wallet’s exposure surface. These techniques directly address the attack vectors used in the Aerodrome incident, where DNS hijacking redirected users to a malicious frontend that generated deceptive approval requests.

Prerequisites

This tutorial assumes you are comfortable with command-line interfaces, have a basic understanding of Ethereum transaction structure, and already use a hardware wallet for DeFi interactions. You will need access to an Ethereum RPC endpoint — services like Alchemy or Infura provide free tiers sufficient for personal use. Familiarity with ENS resolution mechanics and ERC-20 approval patterns will help, though the walkthrough explains each concept as it becomes relevant.

Software requirements include a terminal environment, curl or a similar HTTP client, and optionally a local instance of Foundry for advanced simulation. A wallet with existing DeFi positions provides the most relevant testing ground for the approval auditing section.

Step-by-Step Walkthrough

Step 1: ENS Domain Verification. ENS names resolve through smart contracts on Ethereum, making them immune to the DNS hijacking that compromised Aerodrome’s .finance and .box domains. However, not all ENS names are equally trustworthy. Start by verifying the ENS name is controlled by the legitimate project.

Use the ENS manager app or query the registry contract directly. The critical check is the controller and registrant of the ENS name. For Aerodrome, the legitimate ENS name resolves to content hashes that point to decentralized storage like IPFS. When the team directed users to aero.drome.eth.limo during the attack, this ENS-based path was safe precisely because its resolution could not be manipulated through DNS-level attacks.

For any protocol you use, locate the canonical ENS name from the project’s GitHub repository — specifically from the frontend source code or deployment documentation, not from social media posts. Once verified, bookmark the .eth.limo or .eth.link gateway URL. These gateways translate ENS content hashes into loadable web pages without relying on centralized DNS infrastructure.

Step 2: Transaction Simulation Pipeline. Transaction simulation allows you to preview the exact state changes a transaction will produce before you sign it. This catches malicious approval requests regardless of how the frontend presents them.

Set up a simulation endpoint using Tenderly or Ethereum multimillion-forked mainnet environments. Configure your wallet to route all transaction requests through simulation first. Most modern wallets support this through RPC middleware or browser extensions. When you initiate any DeFi transaction, the simulation executes it against a fork of the current blockchain state and reports all resulting balance changes, approval modifications, and contract interactions.

During the Aerodrome attack, simulation would have immediately revealed the malicious nature of the transactions. The fake frontend generated approval requests for unlimited ETH, USDC, WETH, and NFT transfers. A simulation would show these as unexpected token approval changes to an unknown contract address — a clear red flag that would prompt any experienced user to reject the transaction.

For command-line users, Foundry provides the `cast call` and `eth_call` simulation tools. Create a script that takes any transaction parameters and simulates them against a forked mainnet, reporting all ERC-20 approval changes and ETH transfers. Integrate this into your workflow so no transaction reaches your hardware wallet without passing simulation first.

Step 3: Systematic Approval Auditing. Every ERC-20 approval you have ever granted creates a persistent permission. Over months of DeFi activity, these accumulate into a significant attack surface. The Aerodrome attackers exploited this by generating new approvals — but existing approvals on other compromised protocols present equal risk.

Build an approval audit using the `allowance` method on each ERC-20 contract where you hold tokens. For each token, query the remaining allowance for every spender address you have approved. Tools like Revoke.cash aggregate this data, but for advanced users, a custom script provides more control and can be automated.

Create a scheduled task — daily or weekly depending on your activity level — that scans your wallet for active approvals and compares the spender addresses against a whitelist of known, trusted protocols. Any approval to an address not on your whitelist triggers an alert and automatic revocation if configured. This ensures that even if a protocol you once interacted with is later compromised, your exposure is limited to the specific approval amount rather than your entire balance.

Troubleshooting

If ENS gateway URLs fail to load, try alternative gateways. The .eth.limo and .eth.link gateways occasionally experience downtime. IPFS gateways like ipfs.io or cloudflare-ipfs.com can serve the same content if you have the IPFS hash. Maintain a list of multiple gateways for each protocol’s ENS name.

Transaction simulation sometimes produces false positives, particularly for complex DeFi interactions involving multiple contract calls. Learn to distinguish between expected state changes — like the token transfers in a legitimate swap — and suspicious patterns like approvals to unknown addresses or transfers to contracts you did not intend to interact with.

Approval revocation transactions themselves require gas fees. Prioritize revoking approvals for high-value tokens and approvals with unlimited amounts. Small approvals on low-value tokens present minimal risk and can be addressed during regular maintenance windows rather than immediately.

Mastering the Skill

The techniques in this tutorial represent a foundation that you should extend and automate. Build a personal security dashboard that aggregates ENS verification status for all protocols you use, displays real-time approval exposure, and logs simulation results for every transaction you execute. With Bitcoin near $84,648 and Ethereum around $2,767 on November 22, the financial motivation for attackers has never been higher — and neither has the motivation for robust personal security infrastructure.

The Aerodrome DNS hijacking was not an anomaly. It is a preview of the attack surface that emerges when decentralized protocols rely on centralized access infrastructure. By implementing ENS verification, transaction simulation, and systematic approval auditing, you create a defensive perimeter that operates independently of any single protocol’s frontend security. This is the standard that experienced DeFi practitioners must hold themselves to in the current threat landscape.

This article is for educational purposes only and does not constitute financial or security advice. Always verify all security configurations independently before relying on them for asset protection.