Attacks on Rollups

Abstract

A rollup is a network, implemented via smart contracts on a blockchain, that aims to scale that slow but general purpose blockchain. The rollup executes transactions and posts the resulting state root, along with the transaction data, to a blockchain they are built on. As a result, the state root of the rollup network is always recorded on the underlying blockchain. The underlying blockchain is used to derive the state of the rollup itself, meaning that the rollup state cannot be changed arbitrarily or would be easily detected (subject to how its state is updated and recorded on the underlying blockchain). In turn, the rollup inherits some security from its underlying blockchain-but the rollup network itself is not immune to direct attacks. Some attacks are like other network-level attacks (e.g., denial-of-service attacks) while others are a result of the rollup's connection to its underlying blockchain (e.g., re-organization attacks). In this work, we collect a list of known attacks on rollups and illustrate their impact.