Ice Phishing: The 'Login' Button That Drains Your Wallet

Executive Summary: 'Ice Phishing' doesn't steal your password; it steals your permission. By tricking you into signing a malicious Token Approval, hackers can drain your assets at will. This article breaks down the approve function and how to use Revoke.cash.

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1. The Concept: Approve vs. Transfer

In Ethereum/EVM, a smart contract (like Uniswap) cannot touch your tokens unless you give it permission.

There are two ways to interact:

1. Transfer: "Send 10 USDT to Bob." (One-time action).
2. Approve: "Allow Uniswap to spend up to 1,000 USDT from my wallet." (Persistent permission).

The Exploit: Most dApps ask for "Unlimited Approval" (Infinity) for convenience, so you don't have to sign every time you trade. Scammers abuse this.

2. The Attack: The "Security Update"

You receive an email or see a Twitter link: "OpenSea Security Update: Verify your wallet to prevent asset loss."

You click the link. It looks exactly like OpenSea.

You click "Verify."

Your wallet pops up with a transaction request.

• It doesn't say "Send ETH."
• It says "SetApprovalForAll" or "Approve WETH".
• The Spender Address is the hacker's contract.

The Trap: You think you are "logging in" or "verifying." In reality, you just signed a legal document saying: "I authorize this hacker to move ALL my NFTs and WETH whenever they want."

They don't steal your funds immediately. They wait until you deposit more, then drain it all at once.

3. How to Read the Transaction

Before you click "Confirm," look at the Data tab or the transaction simulation.

Red Flags 🚩

1. Function: SetApprovalForAll (This gives 100% control of your NFT collection).
2. Function: Approve (with a massive number like 1.1579e+59).
3. Spender: An unknown contract address (Check it on Etherscan—is it verified? Does it have a name like "Uniswap Router"?).

4. Remediation: Revoke.cash

If you suspect you signed a bad approval:

1. Go to Revoke.cash.
2. Connect your wallet (read-only mode first).
3. Scan for "Unlimited Allowances" to unknown contracts.
4. Revoke them immediately. This costs a small gas fee but cuts the cord to the hacker.

Read More: For a deep dive on how to close these "backdoors", read our guide on The Hidden Backdoor. Also beware of Address Poisoning, which tricks you into sending funds voluntarily.

Conclusion

Your seed phrase is your bank vault key. Your "Approvals" are the authorized signatories. You wouldn't give a stranger power of attorney over your bank account—don't give random websites SetApprovalForAll.