ApprovalForAll Exploit

In the ERC-721 (NFT) standard, setApprovalForAll lets an operator manage all NFTs in a collection for a given owner. Scams exploit this by disguising approval requests as routine marketplace actions or mint/claim steps, tricking users into approving blanket transfer rights to a malicious operator.

Case 1: Premint NFT platform hack in July 2022: $375,000-$421,000 stolen from users who granted setApprovalForAll permissions.

Case 2: NFT Trader hack in December 2023 - Millions in high-value NFTs stolen including Bored Apes and Mutant Apes.

Once approved, the operator can move any NFT in that collection without further confirmations. Phishing sites, fake airdrops, and impersonated brand mints frequently trigger this call behind innocuous UI labels. Because approvals are stored on-chain, risk persists until explicitly revoked. Losses can cascade quickly if multiple NFTs are eligible under the same approval.

• Use a real-time Web3 security tool like Kerberus to detect malicious contracts before granting NFT operator permissions.
• Inspect transaction details and function names before signing.
• Prefer marketplaces that minimize broad approvals or clearly scope them.
• Regularly audit and revoke unneeded operator approvals via reputable tools.
• Use a hardware wallet and least-privilege practices.