Title: Bribers, Bribers on The Chain, Is Resisting All in Vain? Trustless Consensus Manipulation Through Bribing Contracts

Abstract: In this talk, I will present our recent work on trustless consensus manipulation in Proof-of-Stake (PoS) consensus protocols, specifically Ethereum’s consensus protocol.

In this work, we introduce three novel smart contract-based bribery attacks that enable trustless manipulation of PoS consensus with cryptographic guarantees, without trusted intermediaries and offline agreements.

PayToAttest allows an adversary to buy votes to cause chain reorganizations, lowering the economic cost required to reorganize blocks compared to traditional stake-majority approaches.

PayToExit incentivizes validators to voluntarily exit the consensus protocol, increasing the adversary’s relative staking power, therefore threatening liveness guarantees.

PayToBias, a bribery market for biasing Ethereum’s distributed randomness beacon (RANDAO) by auctioning off randomness contributions.

We further implement and analyze these contracts, their gas and economic costs, and demonstrate their practicality and low cost. Additionally, we provide an initial game-theoretic analysis of one of the bribery markets to find the optimal bribe strategies. Our findings reveal newfound vulnerabilities in the incentive compatibility of PoS consensus protocols in the presence of smart contracts and efficient verifiability of validator behavior.