Sécurité12 min de lecture

Sybil Attack ExplainedHow Fake Identities Threaten Networks

A comprehensive guide to understanding Sybil attacks - where a single entity creates multiple fake identities to gain disproportionate influence over a network. Learn how these attacks work, real-world examples, and how blockchain networks defend against them.

What is a Sybil Attack?

A Sybil attack is a security threat where a single adversary creates and controls multiple fake identities (nodes, accounts, or personas) to gain a disproportionately large influence in a network. Named after the subject of the book "Sybil" who had multiple personalities, this attack exploits systems that rely on counting identities for consensus or voting.

In peer-to-peer networks like blockchain, where each node is assumed to represent a unique participant, an attacker can undermine this assumption by running many nodes from the same physical machine or controlled infrastructure.

Healthy Network

Each node represents a unique, independent participant. Voting and consensus reflect true community sentiment.

Under Sybil Attack

One attacker controls 4 fake nodes (66%). They can manipulate votes, spread misinformation, or disrupt consensus.

Interactive Simulation

Honest Nodes: 12
Sybil Nodes: 0
Health:
100%

Types of Sybil Attacks

Direct Attack

High Severity

Attacker directly creates fake nodes to influence honest nodes

Indirect Attack

Medium Severity

Fake nodes attack through intermediary honest nodes

Eclipse Attack

High Severity

Isolating a node by surrounding it with Sybil identities

Routing Attack

Medium Severity

Manipulating network routing with fake identities

Real-World Examples in Crypto

Airdrop Farming

Creating multiple wallets to claim airdrops multiple times

Impact: Dilutes rewards for legitimate usersArbitrum airdrop had significant Sybil activity

Governance Manipulation

Creating fake voters to sway DAO proposals

Impact: Undermines decentralized governanceBeanstalk $182M governance attack

P2P Network Attacks

Flooding networks with fake nodes

Impact: Network performance degradationTor network Sybil attacks

NFT Wash Trading

Trading NFTs between own wallets to inflate prices

Impact: Fake volume and price manipulationLooksRare wash trading controversy

How Networks Prevent Sybil Attacks

Proof of Work (PoW)

Effectiveness:
95%

Requires computational resources to participate, making mass fake identity creation expensive

BitcoinLitecoin

Proof of Stake (PoS)

Effectiveness:
90%

Requires staking tokens to participate, economically disincentivizing attacks

EthereumCardano

Identity Verification (KYC)

Effectiveness:
85%

Linking accounts to real-world identities through verification

BinanceCoinbase

Reputation Systems

Effectiveness:
75%

Building trust over time makes new fake identities less influential

eBay ratingsGitcoin Passport

Social Graph Analysis

Effectiveness:
70%

Analyzing connection patterns to detect fake identity clusters

WorldcoinBrightID

How to Protect Yourself

Verify project legitimacy

Research the team, check audits, and verify social media presence before interacting

Use established platforms

Stick to reputable exchanges and DeFi protocols with proven track records

Check on-chain activity

Use blockchain explorers to verify genuine transaction history and user activity

Be wary of artificial hype

Fake social media followers and engagement can indicate Sybil manipulation

Diversify your holdings

Don't put all funds in projects vulnerable to governance attacks

Stay informed

Follow security researchers and project announcements for attack disclosures

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