Paper 2025/1168
On Frontrunning Risks in Batch-Order Fair Systems for Blockchains (Extended Version)
Abstract
In timing-sensitive blockchain applications, such as decentralized finance (DeFi), achieving first-come-first-served (FCFS) transaction ordering among decentralized nodes is critical to prevent frontrunning attacks. Themis[CCS'23], a state-of-the-art decentralized FCFS ordering system, has become a key reference point for high-throughput fair ordering systems for real-world blockchain applications, such as rollup chains and decentralized sequencing, and has influenced the design of several subsequent proposals. In this paper, we critically analyze its core system property of practical batch-order fairness and evaluate the frontrunning resistance claim of Themis. We present the Ambush attack, a new frontrunning technique that achieves nearly 100% success against the practical batch-order fair system with only a single malicious node and negligible attack costs. This attack causes a subtle temporary information asymmetry among nodes, which is allowed due to the heavily optimized communication model of the system. A fundamental trade-off we identify is a challenge in balancing security and performance in these systems; namely, enforcing timely dissemination of transaction information among nodes (to mitigate frontrunning) can easily lead to non-negligible network overheads (thus, degrading overall throughput performance). We show that it is yet possible to balance these two by delaying transaction dissemination to a certain tolerable level for frontrunning mitigation while maintaining high throughput. Our evaluation demonstrates that the proposed delayed gossiping mechanism can be seamlessly integrated into existing systems with only minimal changes.
Note: This extended version includes additional appendices that were omitted from the conference version due to space limitations.
Metadata
- Available format(s)
-
PDF
- Category
- Applications
- Publication info
- Published elsewhere. Minor revision. CCS
- DOI
- 10.1145/3719027.3744879
- Keywords
- BlockchainBatch-order fairnessDecentralized sequencingFrontrunning attack
- Contact author(s)
-
paul park @ kaist ac kr
yoontaeung @ kaist ac kr
hcnam @ kaist ac kr
deepak @ mystenlabs com
minsukk @ kaist ac kr - History
- 2025-06-20: approved
- 2025-06-20: received
- See all versions
- Short URL
- https://ia.cr/2025/1168
- License
-
CC BY
BibTeX
@misc{cryptoeprint:2025/1168,
author = {Eunchan Park and Taeung Yoon and Hocheol Nam and Deepak Maram and Min Suk Kang},
title = {On Frontrunning Risks in Batch-Order Fair Systems for Blockchains (Extended Version)},
howpublished = {Cryptology {ePrint} Archive, Paper 2025/1168},
year = {2025},
doi = {10.1145/3719027.3744879},
url = {https://eprint.iacr.org/2025/1168}
}