Sybil Attack: What It Is & the Threats It Poses to Blockchains

Blockchain is certainly one of the most exciting new innovations in the financial world. However, this new technology comes with some potential hazards. If you want to avoid major issues, you need to be aware of problems like Sybil attacks. What is a Sybil attack? This guide will help you understand what it is, and to learn how a blockchain network is made more Sybil-resistant.

What Is a Sybil Attack?

A Sybil attack is a type of malicious assault that targets peer-to-peer (P2P) networks. It involves a single entity operating multiple identities at the same time to get undue influence over the network's actions.

This type of attack existed long before blockchain networks. It can be used in just about any sort of P2P network, so it’s a potential threat to many applications. This computer network service attack has gone by many other names, including “pseudospoofing” and “sock puppets.”

The term "Sybil attack" was first coined in 2002 by Brian Zill, at that time a researcher at Microsoft. He named the attack after Sybil Dorsett (neé Shirley Ardell Mason), a renowned psychological patient known for having dissociative identity disorder. Reminiscent of Dorsett's case, a Sybil attack involves multiple identities all being controlled by a single node in a network. Though the identities appear to be completely distinct nodes, the reality is that they all correspond to the same local entity.