Chain-Off Signatures Can Steal Your Tokens? A Deep Dive into Permit Signatures

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In the fast-evolving world of decentralized applications (dApps), user experience is paramount. Features like gasless transactions and seamless token approvals have made interacting with Web3 smoother than ever. However, these conveniences come with hidden risks—especially when it comes to Permit signatures, a powerful but often misunderstood mechanism in the Ethereum ecosystem.

This article unpacks how seemingly harmless signature requests can lead to significant financial loss, using a real-world phishing case as an example. We’ll explore what Permit is, how it works, why it’s being exploited by attackers, and most importantly—how you can protect yourself.

Understanding the Incident: A $100 Loss That Could Have Been Much Worse

On May 11, a user known as “pineapple.eth” took to social media to report losing over $100 after visiting a phishing site disguised as SyncSwap (syncswap[.]network). While the amount may seem small, the underlying attack vector reveals a growing threat in the DeFi space: chain-off signature phishing via Permit.

👉 Discover how hackers exploit invisible signature risks—learn how to stay protected.

Two suspicious transactions were identified:

Both transfers originated from the victim’s wallet (0xA4089…82C3) to two different addresses controlled by the attacker. The key clue? These transfers used transferFrom, which implies prior authorization had been granted to a third-party contract.

But there was no visible approve transaction in the victim’s history.

Instead, investigators found a permit call from a malicious contract (0x00002…d0000)—a silent, off-chain authorization that never appeared in the user’s transaction list. This is where the danger lies: users can be tricked into signing messages that grant full control over their tokens, without ever realizing it.

What Is Permit? The Gasless Approval Mechanism

Permit was introduced through EIP-2612 to improve the user experience around ERC-20 token approvals. Traditionally, to allow a dApp (like a DEX) to spend your tokens, you’d call approve(spender, amount)—a blockchain transaction requiring gas.

With Permit, users sign a message off-chain (no gas required), and the dApp submits that signature on their behalf. This signature contains:

Once verified on-chain, this signature executes what’s functionally equivalent to an approve() call—but without the user paying gas or seeing a traditional transaction.

Here’s a simplified comparison:

function approve(address usr, uint wad) external returns (bool)
function permit(address holder, address spender, uint256 nonce, uint256 expiry, bool allowed, uint8 v, bytes32 r, bytes32 s) external

Uniswap has since expanded this concept with Permit2, a universal authorization standard that supports more complex delegation models and batch operations.

While convenient, this system creates new attack surfaces.

How Permit Signatures Enable Phishing Attacks

In the pineapple.eth case, the attacker hosted a fake dApp interface that prompted the user to “connect wallet” and then immediately requested a signature.

The message likely looked innocuous—perhaps labeled as “Enable Trading” or “Improve UX.” But embedded within was a Permit request authorizing the attacker’s contract to spend exactly 116.239404 USDC, with a deadline set in the year 56300—effectively permanent.

Since the signature happened off-chain:

After obtaining the signature, the attacker simply submitted it on-chain via the permit() function, gaining full allowance to drain the victim’s USDC using transferFrom.

This method is stealthier than traditional approve phishing because:

👉 See how real-time threat detection could prevent silent token theft.

The Bigger Picture: Widespread Exploitation of Permit2

This isn’t an isolated incident. According to Scam Sniffer, over 300 victims have lost approximately $690,000 due to malicious Permit2-based signature attacks since Uniswap’s rollout of the standard.

As of early May 2025:

One of the malicious contracts (0x00002…d0000) has been flagged by MistTrack as part of an active phishing campaign. Funds stolen in USDC were quickly swapped for ETH and laundered through mixers.

Other affected tokens include:

These numbers represent just a fraction of ongoing exploitation. As more dApps adopt Permit and Permit2 for better UX, attackers are shifting focus from traditional phishing (fake approvals) to silent signature harvesting.

Frequently Asked Questions (FAQ)

Q: Can I detect if I’ve signed a malicious Permit message?

Not easily. Unlike on-chain approvals, Permit signatures occur off-chain and leave no direct trace in your transaction history. You must rely on tools like Scam Sniffer or monitor your wallet behavior after signing any message.

Q: Are hardware wallets safe from Permit phishing?

Hardware wallets sign messages securely, but they do not interpret them. If you approve a malicious Permit request on your Ledger or Trezor, it will still be valid. Always verify what you’re signing.

Q: How is Permit2 different from regular Permit?

Permit2 is a centralized contract that manages all approvals for Uniswap and compatible dApps. It supports advanced features like time-limited allowances and one-time permissions—but also increases centralization risk and expands the attack surface.

Q: Can I revoke a Permit signature after signing?

No. Once signed, a valid Permit message cannot be undone unless it expires or is used. However, you can reduce exposure by avoiding indefinite deadlines and limiting approved amounts.

Q: Do wallets warn about risky Permit signatures?

Most don’t. MetaMask and other popular wallets display raw hex data or generic prompts like “Sign this message.” Advanced users can use browser extensions like Scam Sniffer to get real-time alerts.

Q: Is there a way to check my current Permit authorizations?

Yes. Use tools like:

👉 Stay ahead of emerging threats with proactive security tools.

Protecting Yourself in the Age of Silent Approvals

The rise of gasless interactions brings undeniable benefits—but also demands greater vigilance. Here are actionable steps to protect your assets:

  1. Never sign unexpected messages – Treat every signature request like a transaction.
  2. Use wallet extensions that decode signatures – Tools like Scam Sniffer or Rabby Wallet can reveal hidden Permit calls.
  3. Limit approval amounts and deadlines – Avoid "infinite" approvals; use minimal necessary values.
  4. Regularly audit your authorizations – Check Revoke.cash monthly for suspicious allowances.
  5. Educate yourself on EIP standards – Understanding EIP-2612 and Permit2 helps identify red flags.

Final Thoughts

Permit signatures exemplify the double-edged sword of innovation in Web3. They streamline user experience but open doors to invisible, irreversible attacks. As seen in the pineapple.eth case, even experienced users can fall victim to well-crafted phishing schemes that exploit trust and technical opacity.

Staying safe requires more than just caution—it demands awareness of how modern protocols work behind the scenes. By understanding mechanisms like Permit and adopting proactive security habits, you can enjoy DeFi’s benefits without becoming its next victim.

Core Keywords:
Permit signature, EIP-2612, chain-off authorization, DeFi security, token approval, Phishing attack, Permit2, wallet safety