Zero-value signatures cause you to lose authorization because you are signing an "approval," not a transfer. These signature requests may show an amount of zero, but the real operation is hidden in the signature data—once confirmed, you hand over the "spending rights" of a specific token or NFT in your wallet to the counterparty, who can then drain your assets at any time without your knowledge.
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1. Understand What You're Actually Signing in a Zero-Dollar Signature
Every on-chain transaction, whether it involves asset transfers or not, is essentially a function call to a smart contract. The amount is just one parameter.
The typical zero-dollar signature scam works like this: the attacker crafts a transaction request with malicious Hex Data, and the wallet shows an amount of 0, but the real call instructions are encoded in the transaction data. Common examples include:
approve(): Authorizes a contract to spend a specified token you own.
setApprovalForAll(): Grants a contract the ability to manage all your NFTs.
increaseAllowance(): Increases the spending allowance of a specific address.
transferFrom(): Transfers assets from your address.
permit(): Off-chain authorization via EIP-2612, can be completed without gas.
The core of this scam is "Blind Signing"—you see an unreadable string of hexadecimal data, but what you're signing is an authorization that gives away control of your assets.
Prerequisite: The wallet is connected to a page (fake airdrop, fake DApp, fake NFT minting), and the page prompts a signature request.
2. Why It's Called "Zero-Dollar" Yet You Lose Something
"Zero amount" is a psychological trick that makes you think "there's no risk if no money is transferred." But the attacker doesn't care about this specific transaction; they're after the assets you already hold in your wallet.
Step 1: Identify the Typical Signs of a Zero-Dollar Signature
Feature 1: Request amount is 0 or very small (e.g., 0.0001 of some token).
Feature 2: Recipient is a smart contract address, not a regular wallet address.
Feature 3: Wallet interface shows a "Hex Data" field with a long string of hex characters.
Feature 4: You didn't initiate the transaction; you just clicked a "Login", "Verify", or "Claim" button.
Step 2: Distinguishing Between a Regular Transfer Signature and an Approval Signature
Regular Transfer: After signing, assets are immediately sent from your account, completed in one step.
Approval Signature: After signing, assets don't move right away, but the attacker gains the ability to withdraw your funds at any time in the future.
At this stage, most users cannot tell the difference—the signature content in the wallet often only displays an incomprehensible hash value, which is exactly what attackers exploit.
3. How to Check if You've Fallen Victim
Step 3: Use an Approval Checker Tool to Scan Your Address
What to do: Visit Revoke.cash or Etherscan's "Token Approvals" section, enter your wallet address.
How to do it: Look for any contract addresses you don't recognize or haven't actively approved. Pay special attention to entries where the allowance is "Unlimited" (2^256-1).
What constitutes completion: Once scanned, revoke any suspicious or unnecessary approvals.
Common Reasons for Failure
"The popup showed 0 USDT, so I thought since I wasn't sending anything, I confirmed." This is the common mindset of all victims. In reality, in Web3, "signing" and "transferring" are two completely different concepts. Confirming a signature does not equal sending assets, but it can authorize someone else to send your assets.
Risk reminder: Most wallets (especially hardware wallets without screens) can only perform blind signing and cannot parse and display the true content of the operation before signing. Attackers have highly automated the batch deployment of bait contracts, spreading them via fake airdrops, NFT minting, DApp logins, etc. One signature can cause you to lose all transferable assets in your account within seconds.
4. Aftermath: What to Do If You've Signed Something You Shouldn't Have
Step 4: Immediately Revoke Authorization
What to do: Use Revoke.cash or a similar tool to revoke authorization for the suspicious contract. The sooner the better.
How to do it: Connect your wallet, find the approval list on the tool page, and click "Revoke" for each suspicious one.
What constitutes completion: That contract address no longer appears in your approval list.
Step 5: If Assets Have Already Been Taken, Use On-Chain Tools to Track Funds
What to do: Enter your address on a block explorer, check recent transfer records to see when and to which address assets were sent.
How to do it: Copy the destination address from the outgoing transfer record, search it on a blockchain explorer to see subsequent flows.
What constitutes completion: You have identified the fund flow with a TxID as evidence, which can be used to file a report with the police or contact security teams.
Step 6: Switch Wallets (Prevent Re-exploitation by the Same Approval)
What to do: If you are not sure the revocation is 100% effective, the most thorough method is to transfer remaining assets to a brand-new wallet address.
How to do it: Create a new wallet, back up the seed phrase, and transfer the remaining assets out. Do not use that address for any further interactions.
What constitutes completion: Assets have been moved out of the original address, leaving a zero balance.
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How to Confirm the Issue Is Resolved
After completing the above steps, rescore your address on Revoke.cash—if the suspicious approval entries are gone, control has been restored. If assets have been stolen, what you can do is preserve all transaction records (TxID, attacker address, timestamp) as evidence for future recovery. On-chain transactions are irreversible, but promptly revoking approvals can prevent further losses.
