You checked the delegation contract address, confirmed it is on the official whitelist, and then confidently approved the authorization. But don't forget—if the delegation contract is upgradeable, the code it points to today may be safe, but tomorrow it might not be.
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First, understand: Why can upgradeable contracts "swap their core"?
The key to EIP-7702 delegation is two things: which contract address you authorized (the delegation contract), and what code logic this delegation contract currently points to (the implementation contract).
Many wallets recommend users delegate to a proxy contract instead of directly to a specific implementation contract. The official Ethereum EIP-7702 guide explicitly mentions the advantage of the proxy pattern—upgradeability: updating contract logic by pointing the proxy to a new implementation contract.
The proxy pattern allows developers to upgrade the underlying business logic without changing the delegation address. Your delegation looks unchanged, but the code actually being executed has already been swapped.
Attack path breakdown: How a malicious upgrade bypasses your authorization
I have broken down a real attack scenario. Compare it against your own experience:
Step 1: Trick you into signing You see a pop-up in a DApp or wallet saying "Upgrade Wallet" or "Enable Smart Account," and you sign to authorize an upgradeable proxy contract (not direct code).
Step 2: Maintain a false sense of security After authorization, the code the delegation contract points to may be safe and may even execute batch transactions normally. You think "there is no problem."
Step 3: Remote "core swap"
The attacker (or contract owner) uses the proxy contract's upgradeTo function to replace the code it points to with malicious logic, without changing the delegation address.
Step 4: Persistent takeover
Your delegation address still looks like that "safe" proxy contract. But once called, the code executed is already malicious logic. You do not need to sign again, because the code has already been changed while the delegation address itself remains the same. For example, a malicious upgrade could introduce a call to selfdestruct or steal private key signatures.
Correct approach comparison: Check "upgradeability," not just the address
| Approach | Explanation |
|---|---|
| Wrong approach | Confirm the delegation contract address is on the whitelist and then stop caring. |
| Correct approach | 1. Check whether the delegation contract is a proxy contract (look for getImplementation or whether an upgrade function exists). 2. If the proxy pattern is used, check who owns the proxy contract (Owner). 3. Confirm that ownership belongs to a trusted third party (such as a security committee or a well-known protocol), not a single EOA. |
How to check "upgradeability"
[What to do]: Confirm whether the delegation contract you authorized can "swap its core."
[How to do it], in order:
Step 1: Check the proxy status on a block explorer Search for the delegation contract address you authorized on Etherscan.
- View the contract code and search for keywords such as
upgrade,setImplementation, andchangeImplementation. - If these functions exist in the contract code, it is an upgradeable contract.
Step 2: Check the owner address
If it is upgradeable, go to the "Contract" or "Read Contract" tab on Etherscan and look for the owner, proxyAdmin, or admin field. If it shows 0x000...000 (zero address) or a well-known multisig wallet, the risk is relatively manageable. If it shows a personal EOA address or an undisclosed address, the risk is extremely high.
Completion standard: You can determine that your delegation contract is "immutable," or that its upgrade authority is firmly controlled by a trusted entity.
Risk reminder: Wallets can force users to revoke and re-authorize first, in order to remove any upgradeable delegation contracts from the whitelist. Before that happens, DApps should not directly request EIP-7702 authorization signatures and must rely on specific wallet interfaces.
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A reusable checklist for further investigation
Before authorizing any contract next time, go through this checklist:
| Checklist item | Safe state | Danger signal |
|---|---|---|
| Is the delegation contract upgradeable? | Immutable contract | Contains an upgrade function |
| Who controls the upgrade authority? | Multisig wallet/DAO/zero address | A single personal wallet address |
| Is a locking mechanism provided? | Exists and is enabled | Does not exist or is not enabled |
