Sybil attack
A Sybil attack occurs when one person or group pretends to be many different participants. This lets them try to gain more influence than a single participant would normally have.
What is a Sybil attack?
An attacker creates many digital identities, such as accounts, wallet addresses, or nodes. A node is a computer that participates in a crypto network. The network sees these identities as separate participants, even though they’re all controlled by the same party.
This is especially a problem when a system simply counts identities. For example, lots of extra accounts might mean more votes, rewards, or connections. But creating lots of addresses or nodes doesn’t automatically mean someone can take over a blockchain’s consensus.
An example of a Sybil attack
Suppose a dApp holds a vote with the rule: one wallet address equals one vote. One person creates a hundred wallet addresses and votes with each one.
To the dApp, these look like a hundred different voters. In reality, one person is deciding the outcome. That’s a Sybil attack.
Why do Sybil attacks matter in crypto?
Crypto networks are often open: anyone can create a wallet address or run a node without permission. That’s useful, but it also means a network can’t automatically tell whether many addresses really belong to different people.
Sybil abuse can happen in connection with airdrops, DAO votes, or rewards. Someone may use many wallets to try to get an unfairly large share of tokens or rewards. So it isn’t always an attack on the blockchain itself.
Networks can reduce the risk by not tying influence only to the number of accounts. With Proof of Work, influence depends on computing power. With Proof of Stake, it depends on the stake put up. Connections between nodes and voting often need additional safeguards.
