Sybil Attacks

A Sybil Attack is a type of attack on a peer-to-peer network where a malicious actor operates many fake identities simultaneously. With this strategy, a single actor can gain a disproportionately large influence.

In pseudo-anonymous environments, it's not very difficult to spin up another account and pretend that it's run by a different user.

Doing this at scale allows a single actor to hold an advantage in a decentralized system, whether it be for voting, skewing majority opinions, or generally centralizing power in the system.

What Does A Sybil Attack Look Like?

Tor: running a high number of nodes in hopes of being able to piece together communication routes, deanonymizing the users.

Blockchains: a 51% attack on Bitcoin or another network.

Social media: having a large number of bot accounts all echo the same ideas and interact with the same posts.

How To Prevent Them

Identity validation, reputation systems, captchas (for bot networks), and economic fees (prevents spam) are some known preventative methods.