A wallet drainer is malicious code that empties crypto wallets. It is hidden on a fake website that looks like a well-known service, such as an exchange, an NFT project or an AirdropAirdropWhen a project sends free tokens straight to people's wallets, often to promote itself, though fake airdrops are also a common scam.. When you connect your wallet and approve what appears, you are really giving the scammer permission to take your crypto. They don't need your seed phraseSeed phraseA list of 12 or 24 words that backs up every key in your wallet, so whoever has the words can restore the wallet and take the crypto.: your signature is enough.
How does it work?
In Self-custodySelf-custodyHolding the private keys to your crypto in your own wallet, so nobody else controls it but all the responsibility for the keys is yours., you confirm every action by signing it in your wallet. A drainer abuses that:
- Permission to move tokens. On Ethereum and similar networks, you can give a smart contractSmart contractA program that runs on a blockchain and automatically carries out what it was written to do once certain conditions are met. permission (an approval) to move tokens on your behalf. If that permission goes to a scammer, they can empty those tokens at any time, even much later.
- A signature that looks harmless. Some requests look like an ordinary login but actually grant permission to move tokens.
- A direct transaction. Sometimes a transaction that sends everything to the scammer's address is simply hidden behind a button such as "Claim reward".
Drainers are often sold as a service. Groups such as Inferno Drainer rented ready-made kits to scammers and took 20% of the loot. According to the security firm Scam Sniffer, wallet drainers stole about 494 million dollars from 332,000 wallets in 2024. In 2025 losses fell to about 84 million dollars, but the scams are still common.
How do you protect yourself?
- Only visit sites you know, and type the address yourself instead of clicking links in messages or ads.
- Read what you are approving. If your wallet asks for an approval, "approve" or "permit" you don't understand, cancel.
- Be wary of free tokens and rewards. Airdrops and "prizes" that require you to connect your wallet are the most common bait.
- Use a separate wallet with a small amount for new sites, and keep most of your crypto elsewhere, ideally in a hardware walletHardware walletA small device that keeps private keys offline and signs transactions inside the device, so the keys never reach your computer or phone..
- Revoke old approvals. Block explorers such as Etherscan show which approvals your wallet has given.
A hardware wallet doesn't protect against everything, though. If you confirm a malicious signature on the device, it goes through. What matters most is knowing what you are approving.
Everything in Myntkaup Learn is written and regularly reviewed by the Myntkaup editorial team. It is for education and is not investment advice. Editorial policy. Updated 2 November 2026.