Sybil attack

A Sybil attack is when one person or group runs many wallets or accounts to look like many separate users, typically to claim a bigger share of an airdrop. ethereum.org's glossary defines Sybil attacks as individual humans tricking a system into thinking they are multiple people to increase their influence. In airdrops the influence is tokens. The Arbitrum Foundation describes finding Sybil accounts before its 2023 airdrop by graphing every Arbitrum One transaction and collapsing large, tightly connected clusters of accounts into a single recipient.

Its published anti-Sybil rules also subtracted a point from wallets whose transactions all fell within 48 hours, and from wallets holding less than 0.005 ETH that had used no more than one smart contract. Hamster Kombat's whitepaper said its first allocation would weigh whether players had brought in bots, and Decrypt reported in September 2024 that 2.3 million users were cut for apparent cheating. Rules like these apply to any wallet that matches them, real user or not; see airdrop eligibility.