Front-running Attack in Sharded Blockchains and Fair Cross-shard Consensus
Jianting Zhang
Network and Distributed System Security (NDSS) Symposium 2024 · Day 2 · Blockchain Security
This talk by Jianting Zhang from the NDSS Symposium unveils a critical, previously unaddressed security vulnerability in **sharded blockchains**: a novel form of **front-running attack** that exploits a property termed **finalization unfairness**. Sharding, a widely adopted technique to boost blockchain scalability by processing transactions in parallel across smaller network partitions (shards), paradoxically introduces a new attack surface. The core issue lies in the inherent processing-execution difference between intra-shard and cross-shard transactions, creating a window for adversaries to manipulate transaction ordering.