Blockchain Glossary

Sybil Attack

A Sybil attack is a kind of security threat on an online system where one person tries to take over the network by creating multiple accounts, nodes or computers. For example a Sybil attack can take place when somebody runs multiple nodes on a blockchain network. Attackers may be able to out-vote the honest nodes on the network if they create enough fake identities (or Sybil identities). They can then refuse to receive or transmit blocks, effectively blocking other users from a network.