Sivilla Attack is a type of cyber threat in distributed systems, where a single attacker creates many fake accounts or nodes and uses them for manipulation. The goal is to gain disproportionately large influence over the network, undermine decisions, voting, or trust in the system. The name comes from the image of multiple identities, where one 'substance' disguises itself as dozens or hundreds of individual participants.
What is the risk: in many decentralized protocols, it is assumed that each node or user is an independent vote. If one attacker controls a large share of the 'votes', they can falsify the voting results, block or substitute messages, manipulate ratings, or even influence consensus mechanisms. In practical examples, this can affect P2P networks, recommendation systems, online surveys, and certain blockchain processes.
Protection against Sybil is always a balance between openness and verification. Countermeasures include requirements that complicate the mass creation of identities: Proof-of-Work or Proof-of-Stake (resource expenditures/stakes for participation), reputation systems, KYC in centralized services, CAPTCHA for automated bots, rate limiting of new account creation, and cross-checking of node behavior. Hybrid approaches are also effective - when simple checks are combined with economic barriers and social proof of trust.
Conclusion: Sybil is not just a technical problem, but also a question of system design and trust models. True resilience to this attack requires a smart combination of technical barriers, economic incentives, and careful monitoring of participant behavior.
In recent years, this type of attack has become much harder to implement than at the beginning of the creation of most cryptocurrencies, but one should never let their guard down, as the thirst for easy money is a very powerful force.