Finality Attack

Overview

A finality attack targets the mechanism by which a blockchain decides that history is irreversible or economically impractical to change. The attacker may create conflicting histories, corrupt finality votes, exploit implementation flaws, or acquire enough consensus influence to violate assumptions.

Methods depend on network design and can include majority attacks, validator equivocation, long-range attacks, network partitioning, weak-subjectivity abuse, or coordinated censorship. Some systems make reversal technically impossible after finalization, while others rely on probabilistic confidence or social recovery.

Services should understand the network’s actual finality model, monitor conflicting votes and reorganizations, diversify node views, and delay irreversible fulfillment appropriately. Incident plans must define how to respond when protocol finality, economic finality, and application settlement disagree.

An auditable record of Finality Attack should link proposals, signatures, transactions, blocks, proofs, confirmations, upgrades, and finality changes to the governing policy or model version, source evidence, decision, approver, exception, action, and final outcome.

Finality Attack is an attack or weakness pattern that attempts to reverse, conflict with, or undermine transactions or blocks that participants expected to be permanently settled. Finality attacks exploit the assumptions behind irreversible settlement, so acceptance policies must reflect each network’s consensus and recovery model.

Assessment of Finality Attack should trace an attack or weakness pattern that attempts to reverse, conflict with, or undermine transactions or blocks that participants expected to be permanently settled from prerequisite and entry point through observable impact on the affected service. A theoretical weakness or scanner result involving attack, weakness pattern that attempts to reverse, and conflict with should not be reported as exploitation without corroborating logs, transactions, or configuration evidence. Prevention, detection, containment, and recovery for the Finality attack path should be tested against the architecture associated with attack, weakness pattern that attempts to reverse, and conflict with.