DAG-based blockchain protocols show multiple weaknesses to order manipulation attacks
Competition, Collusion, and Corruption: The Spectrum of MEV Attacks on DAG-Based BFT Consensus Protocols
Cryptography and SecurityDistributed, Parallel, and Cluster Computing
Summary
Some computer systems that confirm transactions on blockchains try to work well even if some participants are dishonest. But in systems where many participants suggest transaction blocks at the same time, attackers can reorder transactions to make money. The paper organizes these kinds of attacks into groups and tests how well six real systems resist them. It finds that all tested systems are vulnerable to some of these attacks, mostly because of how they are designed, not how hard attackers try.
What this means in practice
- •For blockchain protocol designers: Identify how design choices in DAG-based BFT protocols affect vulnerability to transaction ordering attacks, guiding safer protocol implementations.
- •For blockchain security teams: Measure and anticipate which maximal extractable value attacks a deployed DAG-based blockchain protocol may face, improving defense strategies.
Authors
Iliya Mirzaei, Heer Patel, Chenyuan Wu, Mohammad Javad Amiri
Abstract
Byzantine Fault-Tolerant (BFT) protocols guarantee safety and liveness despite the malicious failure of nodes. However, they do not prevent adversarial manipulation of transaction order, where the order a proposer assigns diverges from the order in which clients submitted their transactions. Exploiting this discretion for profit is known as maximal extractable value (MEV), and it is intensified in DAG-based BFT protocols, where every replica proposes blocks concurrently rather than routing transactions through a single designated proposer each round. The proliferation of MEV attacks on DAG-based BFT protocols has made the resulting landscape difficult to navigate: attacks are reported individually, on different protocols, and under different metrics, making it unclear whether two attacks differ fundamentally or merely in how they are described. This paper closes that gap by presenting an attack space for MEV on DAG-based BFT protocols, organized around four families: the adversary, the protocol, the target, and the deployment. For each family, we identify the dimensions that shape an attack's impact. Each point in the attack space fixes one value per dimension, thereby representing a distinct, potential MEV attack, which can then be instantiated on a specific DAG-based BFT protocol. We perform a set of experiments, each isolating a single dimension where the protocol permits it, to empirically measure its effect on the success rate of MEV attacks against six production DAG-based BFT protocols. Our experimental evaluation reveals that every protocol we evaluate is vulnerable to at least a subset of the MEV attacks in this space, and that which attacks succeed is mostly dictated by the protocol's own design rather than by attacker effort.