Sybil Attack
An attack where a single individual or organization creates many fake identities to gain disproportionate influence in a network.
Named after the book 'Sybil' (about a woman with multiple personalities), this attack happens when someone creates thousands of fake accounts to cheat in voting systems, skew reputation scores, or manipulate airdrops. Decentralized networks defend against this using mechanisms like Proof of Work, Proof of Stake, or Proof of Humanity.
graph LR
Center["Sybil Attack"]:::main
Pre_network_security["network-security"]:::pre --> Center
click Pre_network_security "/terms/network-security"
Pre_consensus_mechanisms["consensus-mechanisms"]:::pre --> Center
click Pre_consensus_mechanisms "/terms/consensus-mechanisms"
Rel_51_percent_attack["51-percent-attack"]:::related -.-> Center
click Rel_51_percent_attack "/terms/51-percent-attack"
Rel_dao_governance["dao-governance"]:::related -.-> Center
click Rel_dao_governance "/terms/dao-governance"
Rel_byzantine_fault_tolerance["byzantine-fault-tolerance"]:::related -.-> Center
click Rel_byzantine_fault_tolerance "/terms/byzantine-fault-tolerance"
classDef main fill:#7c3aed,stroke:#8b5cf6,stroke-width:2px,color:white,font-weight:bold,rx:5,ry:5;
classDef pre fill:#0f172a,stroke:#3b82f6,color:#94a3b8,rx:5,ry:5;
classDef child fill:#0f172a,stroke:#10b981,color:#94a3b8,rx:5,ry:5;
classDef related fill:#0f172a,stroke:#8b5cf6,stroke-dasharray: 5 5,color:#94a3b8,rx:5,ry:5;
linkStyle default stroke:#4b5563,stroke-width:2px;
🧒 Explain Like I'm 5
Imagine if one kid in [class](/en/terms/class) brought 50 hats and changed them quickly to vote 50 times for the class president. That's a Sybil attack—one person pretending to be a crowd of people to cheat.
🤓 Expert Deep Dive
Crucial for peer-to-peer systems. Defense strategies include: 1. Resource-based (PoW/PoS), 2. Social-based (Vouching/Trust Networks), 3. Biometric (Iris scans), and 4. Fee-based (Making identity creation expensive).