Briefing
A sophisticated phishing attack leveraging Ethereum’s “Permit” signature feature resulted in a $6.28 million loss for a crypto whale on September 18, 2025. This incident highlights a critical vulnerability where legitimate off-chain approval mechanisms are misused to bypass traditional security checks, allowing attackers to drain staked Ethereum (stETH) and Aave-wrapped Bitcoin (aEthWBTC) without gas fees. The attack underscores the escalating threat of EIP-7702 batch-signature scams and direct malicious contract transfers, contributing to August 2025’s $12.17 million in phishing-related losses.
Context
Prior to this incident, the digital asset landscape has seen a concerning surge in phishing attacks, with August 2025 alone registering a 72% monthly increase in losses to $12.17 million across over 15,230 victims. The prevailing attack surface includes sophisticated social engineering tactics and the exploitation of legitimate, yet often misunderstood, smart contract functionalities designed for convenience, such as token approval mechanisms. The absence of gas fees in such off-chain approvals has historically masked malicious intent, rendering users susceptible to seemingly innocuous prompts.
Analysis
The attack leveraged the “Permit” signature feature, intended to streamline token approvals, by disguising malicious activity as a routine wallet confirmation. The attacker combined the Permit signature with the TransferFrom function, enabling the direct draining of assets. Crucially, because the approval occurs off-chain, the transaction did not require gas fees, effectively bypassing a key indicator of on-chain activity and leaving the victim unaware until the funds were already transferred. This method allows for a cost-effective and stealthy exploitation of user permissions, circumventing complex on-chain hacks and high gas strategies.
Parameters
- Protocol Targeted → Ethereum Ecosystem (via Permit feature misuse)
- Attack Vector → Phishing via Malicious Permit Signature
- Financial Impact → $6.28 Million
- Assets Lost → Staked Ethereum (stETH), Aave-wrapped Bitcoin (aEthWBTC)
- Date of Incident → September 18, 2025
- Affected Entity → Crypto Whale
- Detection Firm → Scam Sniffer
Outlook
Users must adopt a more stringent security posture by meticulously scrutinizing all wallet confirmation requests and avoiding the granting of unlimited token permissions. Immediate mitigation steps include regularly reviewing and revoking token approvals on relevant protocols and securing significant holdings with hardware wallets. This incident will likely drive a push for enhanced user education on signature types and the development of more robust wallet interfaces that clearly differentiate between various approval mechanisms, potentially establishing new best practices for off-chain transaction security.
Verdict
The escalating misuse of legitimate protocol features like Ethereum’s Permit for sophisticated phishing attacks represents a critical and evolving threat that demands immediate, proactive user vigilance and enhanced platform-level safeguards.
Signal Acquired from → ainvest.com
