Drainer Signatures on Perp DEXs: How They Work and How to Spot Them

Drainer attacks have become one of the largest sources of losses in DeFi. Chainalysis research has shown that the Drainer-as-a-Service ecosystem is now highly industrialized: attackers can subscribe to ready-made toolkits and launch sophisticated signature phishing campaigns against perp DEX users. Source: WalletConnect.

If you actively trade on platforms such as Hyperliquid, dYdX, GMX, or other decentralized perpetuals venues, understanding how drainer signatures work is a basic security requirement.

Key comparison table

What Is a Drainer Signature Attack?

A drainer signature attack tricks a user into signing a request that looks harmless but actually authorizes asset movement.

Unlike private key theft, drainer attacks abuse legitimate authorization mechanisms in the Ethereum ecosystem, including:

• ERC-20 approve: lets a third-party address spend a specified amount of tokens.
• EIP-2612 permit: enables token approval through an off-chain signature, without an on-chain approval transaction from the user.
• EIP-712 structured data signing: used to authorize many types of structured operations.
• EIP-4337 account abstraction flows: can involve bundled or batched authorization logic.

These mechanisms are useful and necessary in normal DeFi activity. The problem is that drainers exploit their complexity, disguising malicious authorizations as routine DApp interactions.

Why Perp DEX Users Face Extra Risk

High-frequency signing creates risk windows

Perpetual futures traders interact with DEX contracts frequently: opening positions, adding margin, adjusting collateral, claiming funding, and managing orders may all involve signatures.

The more often you sign, the easier it is to develop confirmation fatigue. That is exactly what attackers rely on: a user who clicks through a familiar-looking signature prompt without checking the details.

Large USDC approvals are a prime target

On many perp DEX workflows, users approve or deposit significant amounts of USDC. A phishing site can imitate this flow and present a fake “USDC approval” request where the spender address is controlled by the attacker instead of the real protocol.

If you only look at the token name and not the target contract address, you may accidentally authorize a drainer to move a large balance.

Permit signatures are especially dangerous

EIP-2612 permit allows token approval through an off-chain signature rather than an on-chain approve transaction. That has several security implications:

• The signing process does not create an immediate on-chain transaction from your wallet.
• It does not consume gas, which can make it feel less serious.
• Your wallet activity may not show an outgoing approval transaction at the time of signing.
• Once the attacker has the signature, they can submit it on-chain and use it to move tokens.

From the user’s perspective, the asset transfer may be the first visible sign that something went wrong.

Permit signatures can also look similar to ordinary login signatures such as Sign-In with Ethereum, making them one of the hardest drainer methods for regular users to identify.

Technical Anatomy of a Drainer Signature

A typical EIP-712 drainer signature may include fields like this:

Type: EIP-712 structured data signature

Domain:
  name: [Impersonated protocol name]
  version: 1
  chainId: 1 or 42161, depending on the target chain
  verifyingContract: [Drainer contract address pretending to be a DEX contract]

Message:
  owner: [Victim address]
  spender: [Drainer-controlled contract address]
  value: [All or most of the user’s token balance]
  deadline: [A future timestamp]
  nonce: [Current nonce]

If your wallet displays this data in a readable way, you can often spot the problem: the verifyingContract or spender does not match the official protocol address.

If your wallet only shows raw hex data, most users have no realistic way to verify what they are signing.

How to Spot a Drainer Signature: Practical Checklist

Before signing any request, check the following:

• verifyingContract address: Does it exactly match the official contract address of the DEX you are using? Check every character.
• spender address: For permit signatures, the spender should be a contract you clearly recognize and trust.
• value field: Is the requested amount larger than the current action requires? Be especially cautious if it is close to your full balance.
• deadline field: Is the expiry reasonable? A normal action usually does not need a deadline years in the future.
• Source of the request: Did you initiate the action on the official website, or did the signature prompt appear unexpectedly?

If anything looks unfamiliar, reject the signature and verify the site, contract addresses, and wallet prompt before trying again.

How OneKey Helps Defend Against Drainers

OneKey Wallet includes protections designed to make drainer attempts easier to identify:

• Readable EIP-712 parsing: OneKey parses structured signing data and shows key fields such as owner, spender, and value in a human-readable format instead of raw hex.
• Contract risk labeling: Known malicious contract addresses can be flagged with warnings.
• Transaction simulation preview: For on-chain approvals, OneKey can simulate the result before signing, making it clearer that you are authorizing a specific amount of USDC to a specific address.
• Large approval warnings: Extra warnings can appear when an approval request is unusually large relative to your holdings.
• Open-source verification: OneKey’s OneKey GitHub repositories allow security researchers to review how protection logic is implemented.

A hardware wallet also plays an important role. Attackers cannot automatically sign on your behalf without physical confirmation on the device. The information shown on the hardware wallet screen cannot be silently altered by malware running on your computer.

That said, a hardware wallet is not magic. If you blindly approve a malicious signature on the device, the attack can still succeed. The device gives you a trusted confirmation surface; you still need to read it.

For active perp traders, a practical workflow is to use OneKey Wallet for signing visibility and transaction simulation, then trade through OneKey Perps with the habit of reviewing every approval and signature before confirmation.

You should also periodically review historical token approvals with tools such as Revoke.cash and revoke permissions you no longer need. Reducing old approvals reduces the surface area available to drainers.

Known High-risk Drainer Attack Vectors

Common drainer entry points include:

• Fake perp DEX frontends promoted through search ads or social media.
• Impersonated airdrop, rebate, or trading rewards pages.
• Malicious “connect wallet” popups that request more than a login signature.
• Fake support links sent through Discord, Telegram, X, or direct messages.
• Compromised websites that inject malicious wallet prompts into otherwise familiar pages.
• Approval or permit requests that imitate normal USDC collateral flows.

Treat any unexpected signature request as suspicious, especially when it involves USDC, stablecoins, or wallet-wide permissions.

FAQ

Q1: What is the difference between permit and a normal approve?

approve is an on-chain transaction. It requires gas and leaves an on-chain approval record.

permit is an off-chain signature. It does not require gas when you sign it, and the counterparty can later submit it on-chain. Because you may not see an immediate outgoing transaction in your wallet history, it can be harder to notice and respond to.

Both can be dangerous if granted to a malicious spender.

Q2: What should I do if I already signed something suspicious?

If it was an approve, revoke the approval immediately using a trusted approval management tool such as Revoke.cash.

If it was a permit, revoking may not help if the attacker can still submit or has already submitted the authorization. Move the affected tokens to a fresh address as quickly as possible. Time matters; in many cases the window is only minutes.

Q3: Can a drainer still succeed if I use a OneKey hardware wallet?

A hardware wallet significantly raises the difficulty because every signature requires physical confirmation, and malware on your computer cannot silently change what appears on the device screen.

However, if you confirm a malicious request without understanding it, the attack can still work. Hardware wallets reduce blind-signing risk, but user review remains essential.

Q4: What is Drainer-as-a-Service?

Drainer-as-a-Service is a commercial model where attackers subscribe to ready-made drainer kits instead of building the infrastructure themselves. These kits often include phishing pages, wallet-draining logic, and revenue-sharing arrangements based on stolen funds.

This lowers the technical barrier for attackers and has contributed to the growth of drainer campaigns. Chainalysis has covered this trend in its research.

Q5: Can perp DEX platforms prevent drainer attacks by themselves?

Legitimate perp DEX frontends may filter known malicious addresses and warn users about suspicious activity. But attackers usually operate through separate phishing sites that bypass the official frontend entirely.

That is why wallet-level protection matters. A wallet that parses signatures, highlights risky fields, and simulates transactions can help protect you even when the website you are visiting is malicious.

Final Thoughts: Real Security Starts with Reading Every Signature

Drainer attacks work because users approve signatures they do not understand. Security tools can make signatures easier to read, but the final defense is your own review of every request.

Download OneKey Wallet and use its signature parsing, risk warnings, hardware confirmation, and transaction simulation features to trade with better visibility. If you trade decentralized perpetuals, consider using OneKey Perps as part of a safer workflow: verify the site, read the signature, confirm the contract, and only then sign.

Risk warning: This article is for educational purposes only and is not investment advice, legal advice, or a security guarantee. Drainer techniques continue to evolve, and no method can provide complete protection. Stolen on-chain assets are usually difficult or impossible to recover. Crypto trading involves significant market risk, and leveraged trading can result in losses greater than your initial capital.