Permit-based signatures fuel 2025’s wallet drains, as a $6.5 million DeFi theft shows. This Web3 security tool helps users by focusing on the ‘pre-sign’ moment.
2025 has been brutal for crypto users. Across hacks, scams, and wallet takeovers, security trackers estimate roughly $2.47 billion in losses in the first half alone, with most dollar damage tied to compromised wallets and large-scale phishing waves at the signature prompt.
Wallet drainers have matured into ‘drainer-as-a-service’ kits, siphoning roughly $494 million in 2024 and blending social engineering with UI tricks that blur what a signature authorizes.
The most dangerous part is that much of the damage happens before any onchain transaction appears, at the signature screen. Approvals granted via offchain signatures can arm an attacker with everything they need — and the final “drain” posts to the blockchain only after the victim has already clicked Sign.
One of the most striking examples came in September, when a long-active DeFi wallet lost more than $6.5 million in stETH and aEthWBTC in a matter of minutes. The theft was not the result of a new zero-day exploit. Instead, it highlighted a much more basic but devastating vector: permit signatures.
Approve is the standard ERC-20 method set onchain that defines who can spend and how much. It costs gas, which creates useful friction before you commit.
Permit works differently. It’s an offchain signature that grants spending rights; the other party later submits it onchain. It feels harmless because there’s no gas at sign time. Think of it as a blank check that the holder can cash anytime.
Blockchains faithfully execute instructions. When a malicious approval or permit exists, the network does exactly what the signature authorizes. Defense, therefore, must surface risk before the click — at the point of signature — and must contextualize what a message will enable across tokens, contracts, amounts, and counterparties.
That means real-time simulation of both transactions and offchain signatures, threat intel on known drainer infrastructure, entity screening and clear human-readable explanations of consequences.
Wallet drainers are scaling because they exploit human behavior. Signing a Permit feels easier and safer, but it opens the door for scammers to move funds instantly. Even experienced DeFi users, active for years across Lido, Aave and other protocols, have fallen victim.
By catching malicious requests before they hit the blockchain, pre-sign tools shift the balance of power back to the user.
Technical patches cannot solve this problem because the blockchain executes exactly what it is told. The real solution lies in pre-sign protection: surfacing risks before the user clicks ‘Sign’.
Web3 security suite Web3 Antivirus focuses on the pre-sign moment. The product simulates what a signature or transaction will actually do, flags dangerous approvals, and warns if a request routes to suspicious contracts or addresses. For users, it acts like an always-on co-pilot that translates complex payloads into plain outcomes before anything reaches the chain.
For platforms, Web3 Antivirus’s Data API brings these checks into the decentralized application (DApp) experience, enabling wallets, marketplaces, and DeFi frontends to screen signatures and transactions in real time, tie alerts to risk policies, and automate protective actions. This can include sanctions/KYT screening, heuristic drainer detection and pre-broadcast blocking.
The recent $6.5M drain shows how these controls matter. Web3 Antivirus’s monitoring attributed the theft to phishing permits that armed the attacker; a pre-sign simulation would have highlighted the resulting allowances and the contracts on the other end of the request, giving the user a clear “don’t sign” moment.
Here are five practical tips for users:
The $6.5M drain was not the first case, and it will not be the last. But it highlights exactly how today’s biggest threats are not protocol bugs; they are social engineering attacks at the signing layer.
Web3 keeps evolving — and so do social-engineering kits that weaponize convenience. With pre-sign visibility, simulation, and policy-driven controls, users and platforms can keep that convenience while blocking the “blank check” moments that power today’s wallet drains.
Find out more about Web3 Antivirus
Disclaimer. Cointelegraph does not endorse any content or product on this page. While we aim at providing you with all important information that we could obtain in this sponsored article, readers should do their own research before taking any actions related to the company and carry full responsibility for their decisions, nor can this article be considered as investment advice.
