VEYRNOX · Learn · Drainer Contract
Drainer Contract
A drainer contract is a malicious smart contract that, once approved by a victim, transfers assets out of the victim’s wallet to attacker-controlled addresses. Drainers are the payload behind most modern phishing and fake-airdrop scams.
How it works
The victim is directed to a fake dApp — a spoofed NFT mint, a fake airdrop, or a cloned DeFi frontend. Signing the "claim" or "connect" prompt actually approves a token allowance to the drainer, or signs an EIP-712 permit that lets the drainer move assets without a second confirmation. The drainer sweeps every approved token, NFT, and native asset in one transaction. Once approvals are signed, no wallet control can revoke them retroactively — the loss is on-chain.
Why it matters
Drainer-as-a-service kits (Inferno, Pink, Angel, others) power the majority of high-value wallet compromises. A single misclick on a spoofed site can drain a wallet in seconds. The defence is not stronger passwords — the attack does not touch them — but transaction preview, phishing-site detection, and refusal to sign opaque approvals.
Related concepts
- Phishing Site Detection — Phishing site detection is the wallet-level defence that blocks connections to fraudulent domains impersonating legitimate dApps, exchanges, or bridges.
- Transaction Simulation — Transaction simulation is a pre-signing check that runs a proposed transaction against a forked node state and reports the expected net asset change to the user before they sign.
- Address Poisoning — Address poisoning is a wallet-address confusion attack in which an attacker sends a zero-value or dust transaction from an address that visually resembles one of the victim’s frequent contacts.
- Threat Intelligence Platform (TIP) — A Threat Intelligence Platform (TIP) is a backend service that aggregates, curates, and distributes real-time threat signals — phishing domains, drainer contracts, sanctioned addresses, suspicious dApps — to consuming clients.
Frequently asked questions
Can I revoke a drainer approval after signing?
Only if the drainer has not already swept the assets. Once transferred on-chain, the loss is final.
Do hardware wallets stop drainers?
No — hardware wallets sign what they are shown. If the user approves the drainer contract, the hardware wallet signs it correctly.
How does transaction simulation help?
It computes the expected net balance change before signing, so a drainer that appears to be a mint but actually sweeps your wallet is exposed as a large negative delta.
In Veyrnox
Veyrnox blocks drainers at two points. Phishing-site detection refuses to connect to known malicious domains, and Transaction Simulation shows the net asset change of any approval before the user signs, so a hidden sweep is visible in plain English.