Angel Drainer Wallet Drain Campaign Exploits Permit Function Across 20 Blockchain Networks

Cryptocurrency users face an escalating threat from sophisticated wallet-draining operations that exploit a little-understood feature of ERC-20 tokens. A detailed investigation published on December 22, 2023, by Check Point Research exposes the inner workings of Angel Drainer, a notorious phishing group that has been systematically draining wallets across Ethereum, Binance Smart Chain, Polygon, Avalanche, and nearly 20 additional blockchain networks.

The Exploit Mechanics

The attack vector relies on the ERC-20 permit function, a feature designed to improve user experience in decentralized applications. The permit function allows token holders to approve a spender to transfer tokens on their behalf through an off-chain signature rather than an on-chain transaction. While this reduces gas fees and streamlines DeFi interactions, it creates a critical vulnerability when exploited by malicious actors.

Angel Drainer operates by luring victims to counterfeit websites through fake airdrop campaigns promoted on social media and via email. Once a user connects their wallet, they are prompted to interact with a malicious smart contract disguised as a token claim mechanism. The contract stealthily triggers an approval event, granting the attacker permission to transfer the victim’s tokens. Because the signature occurs off-chain between the wallet and the phishing website, no transaction is recorded on the blockchain, leaving almost no trace for victims to detect until their funds have already been moved.

Checkpoint researchers traced the attack through a specific transaction hash and identified a recurring attacker address associated with the Angel Drainer group: 0x412f10aad96fd78da6736387e2c84931ac20313f. The analysis revealed a multi-step execution involving ownership transfer events, approval events, and subsequent token transfers designed to drain assets across multiple chains simultaneously.

Affected Systems

The scope of the Angel Drainer campaign is significant. The group targets users across Ethereum, Binance Smart Chain, Polygon, Avalanche, and approximately 20 other networks. Any user holding ERC-20 compatible tokens on these chains is potentially vulnerable to the permit-based attack. The phishing infrastructure leverages the same CDN distribution model that legitimate DeFi applications use, making malicious websites appear virtually identical to authentic platforms.

This campaign persists even after the shutdown of similar groups like Inferno Drainer, which previously assisted in stealing over $80 million in cryptocurrency. Angel Drainer has effectively filled the void, offering wallet-draining scripts and support services to other hackers in exchange for a percentage of stolen funds, operating as a scam-as-a-service enterprise.

The Mitigation Strategy

Protecting against permit-based drain attacks requires a multi-layered approach. Users should verify the authenticity of any website before connecting their wallet, paying close attention to URL spelling and domain legitimacy. Hardware wallets like Ledger and Trezor provide an additional layer of security by requiring physical confirmation of transaction details before signing.

MetaMask has responded to this growing threat by expanding its security Snaps ecosystem. As of December 2023, 12 security-focused Snaps are available through the MetaMask Snaps Directory, including Wallet Guard for transaction insights and proactive alerts, Forta for scanning addresses against known scammer databases, and Blockfence for evaluating transaction safety before execution. These tools can detect suspicious approval patterns and warn users before they sign malicious permit requests.

Lessons Learned

The Angel Drainer campaign underscores a fundamental tension in DeFi design: convenience features that reduce friction for legitimate users also create attack surfaces for exploitation. The permit function was designed to save users gas fees and simplify interactions, but its off-chain nature means that victims often have no on-chain evidence of the attack until it is too late.

The persistence of scam-as-a-service operations like Angel Drainer, even after law enforcement actions and shutdowns of competing groups, demonstrates that the phishing ecosystem is self-sustaining and adaptable. As long as cryptocurrency wallets hold value and users can be socially engineered into signing malicious requests, these attacks will continue to evolve in sophistication.

User Action Required

Cryptocurrency holders should immediately review their token approvals using tools like Revoke.cash to identify and revoke any suspicious spending permissions. Users who have recently connected their wallets to unfamiliar websites should move their funds to a fresh wallet address as a precaution. Installing a security Snap like Wallet Guard or Web3 Antivirus in MetaMask adds a critical verification layer that can intercept malicious permit requests before they are executed.

With Bitcoin trading at $43,997 and Ethereum at $2,326 on December 22, 2023, the total value at risk across the cryptocurrency ecosystem has never been higher. Vigilance and proactive security measures are not optional — they are essential for anyone holding digital assets.

Disclaimer: This article is for informational purposes only and does not constitute financial or security advice. Always conduct your own research before making decisions about cryptocurrency security.