You send a small test transfer, the recipient confirms receipt, but when you send a larger amount, it ends up in a hacker's wallet. This problem isn't because the test failed—the test itself becomes a "signal" that allows the hacker to poison your wallet during the short window between your test and real transfer.
Step 1: Understand the Full Timeline of Poisoning After a Test Transfer
【What to do】 Reconstruct the real order of the attack and find where the poisoning is inserted.
【How to do it】 Compare your actions to a $50 million poisoning case from December 2025. Check if your sequence matches the attack window:
- You initiate the test transfer: You send a small amount (e.g., 50 USDT) to the target address. The transaction enters the mempool, waiting to be confirmed.
- The hacker monitors the mempool and creates a fake address: The attacker spots your pending transaction. They instantly generate a fake address that has the same first and last characters as your target address. Then they send a dust transfer (e.g., 0.005 USDT) from this fake address to your wallet.
- The fake transaction appears in your history in the "right" spot: Due to gas fees or block ordering, this poisoning transaction may be confirmed before your real test transfer, appearing in your transaction history.
- You copy the address from your history: After confirming the test was received, you go to your transaction history and copy the address—but you've copied the fake address the hacker just planted, not the one you used for the test.
The whole process, from finishing the test to sending the big transfer, can happen in as little as 10–15 minutes.
【Completion standard】 You can explain: poisoning after a test transfer happens during "mempool monitoring" and "copying the address from history"—not because the test itself was wrong.
Step 2: Identify Where the Poisoning Occurs – It's Not the Test, It's the Copy
【What to do】 Confirm which step actually caused the funds to be sent to the wrong address.
【How to do it】 Check your own habits step by step against the following:
- The test transfer itself is not the mistake—you sent the test to the correct address and the recipient received it. This step was safe.
- The problem is the "look back at your history" step—after the test, you go to your wallet's transaction history and try to "copy the last address you used." But that history has already been contaminated by the hacker's poisoning transaction, and you end up copying a fake address that looks the same at the start and end.
- You only check the first and last characters when verifying—wallet interfaces usually show shortened addresses like "0xAbcd...F8b5". The hacker's fake address has exactly the same first 5 and last 4 characters, only differing in the middle.
【Completion standard】 You can confirm: your test transfer succeeded, but the large transfer was made using an address taken from "history" instead of an address book or manual paste.
High risk: Even if your test transfer succeeds and you see it confirmed, a poisoning transaction can still be inserted into your history without your knowledge. In December 2025, a user sent a test of 10 USDT and then transferred 1.59 million USDT. The hacker's poisoning transaction appeared on-chain earlier than the real test. Even by picking the "most recent" entry, the user would copy the fake address.
Step 3: Stop Poisoning After a Test Transfer – A Safe Workflow
【What to do】 After the test but before sending the large amount, verify the address using a method that doesn't rely on your transaction history.
【How to do it】
- After the test, do not copy the address from your history. This is the most critical block. The history may already be poisoned.
- Save the target address in your "address book" or "contacts" in advance. When you make the transfer, select it from there instead of searching your history.
- Verify the full address string, not just the start and end. Compare at least "first 4 characters + middle 4 + last 4" to confirm the whole address matches.
- Before a large transfer, confirm the address with the recipient using a different device or secure channel. Ask them to send the full address again—via a signed message or image—and check it character by character against the address you're about to send to.
【Completion standard】 You can do this: after a test, complete a large transfer without using your history, relying on the address book or manual full verification instead.
How to verify after the transfer: Once the large transfer is done, search for the transaction hash on a block explorer (e.g., Etherscan). On the details page, double-check that the receiving address matches the target address exactly. If you see a wrong address, stop any further actions immediately—on-chain transactions cannot be reversed, but you can prevent additional losses.
