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Asymmetric Mempool DoS Security: Formal Definitions and Provable Secure Designs

Wanning Ding, Yibo Wang, Yuzhe Tang

TL;DR

This work addresses mempool DoS in public blockchains by introducing formal eviction-security definitions and the saferAd-CP admission policy. It proves eviction-based security via a lower bound on total mempool fees and implements a childless-eviction-based CP in Geth, achieving a monotonic price increase and provable resilience against asymmetric eviction DoS. Empirical evaluation on real Ethereum traces shows saferAd-CP yields negligible latency overhead and improves revenue stability under normal workloads, while dramatically increasing attacker costs under eviction attacks (by more than $10^4$). The results offer a formal framework and practical, provably secure mempool designs with direct implications for validator economics and MEV-enabled ecosystems.

Abstract

The mempool plays a crucial role in blockchain systems as a buffer zone for pending transactions before they are executed and included in a block. However, existing works primarily focus on mitigating defenses against already identified real-world attacks. This paper introduces secure blockchain-mempool designs capable of defending against any form of asymmetric eviction DoS attacks. We establish formal security definitions for mempools under the eviction-based attack vector. Our proposed secure transaction admission algorithm, named \textsc{saferAd-CP}, ensures eviction-security by providing a provable lower bound on the cost of executing eviction DoS attacks. Through evaluation with real transaction trace replays, \textsc{saferAd-CP} demonstrates negligible latency and significantly high lower bounds against any eviction attack, highlighting its effectiveness and robustness in securing blockchain mempools.

Asymmetric Mempool DoS Security: Formal Definitions and Provable Secure Designs

TL;DR

This work addresses mempool DoS in public blockchains by introducing formal eviction-security definitions and the saferAd-CP admission policy. It proves eviction-based security via a lower bound on total mempool fees and implements a childless-eviction-based CP in Geth, achieving a monotonic price increase and provable resilience against asymmetric eviction DoS. Empirical evaluation on real Ethereum traces shows saferAd-CP yields negligible latency overhead and improves revenue stability under normal workloads, while dramatically increasing attacker costs under eviction attacks (by more than ). The results offer a formal framework and practical, provably secure mempool designs with direct implications for validator economics and MEV-enabled ecosystems.

Abstract

The mempool plays a crucial role in blockchain systems as a buffer zone for pending transactions before they are executed and included in a block. However, existing works primarily focus on mitigating defenses against already identified real-world attacks. This paper introduces secure blockchain-mempool designs capable of defending against any form of asymmetric eviction DoS attacks. We establish formal security definitions for mempools under the eviction-based attack vector. Our proposed secure transaction admission algorithm, named \textsc{saferAd-CP}, ensures eviction-security by providing a provable lower bound on the cost of executing eviction DoS attacks. Through evaluation with real transaction trace replays, \textsc{saferAd-CP} demonstrates negligible latency and significantly high lower bounds against any eviction attack, highlighting its effectiveness and robustness in securing blockchain mempools.
Paper Structure (17 sections, 2 theorems, 5 equations, 7 figures, 3 tables, 1 algorithm)

This paper contains 17 sections, 2 theorems, 5 equations, 7 figures, 3 tables, 1 algorithm.

Table of Contents

  1. Introduction
  2. Background and Notations
  3. Threat Model
  4. Security Definition
  5. saferAd Framework
  6. Tx-Admission Algorithm of $CP$
  7. Eviction Secure of $CP$
  8. Locking Insecure of $CP$
  9. Implementation Notes on Geth
  10. Revenue Evaluation
  11. Experimental Setups
  12. Revenue Under Normal Transactions
  13. Revenue Under Attacks
  14. Estimation of Eviction Bounds
  15. Performance Evaluation
  16. ...and 2 more sections

Key Result

Lemma 5.1

If a mempool runs Algorithm alg:adTx:AA:framework, the sum of transaction prices in the mempool monotonically increases, or the mempool is considered to be monotonic price-increasing. Formally,

Figures (7)

  • Figure 1: Threat model of a victim mempool: In blue are downstream operators that rely on reading or writing the mempool. In dark blue are the operators in the private transaction path.
  • Figure 2: Experimental setup
  • Figure 3: Block revenue w/w.o. saferAd-CP under Trace $1$.
  • Figure 4: Validator revenue under attacks: With and without saferAd-CP defenses.
  • Figure 5: Block revenue lower bounds.
  • ...and 2 more figures

Theorems & Definitions (6)

  • Definition 4.1: Tx admission
  • Definition 4.2: Tx admission timeline
  • Definition 4.3: Mempool eviction security
  • Definition 4.4: Mempool locking security
  • Lemma 5.1: Monotonic price-increasing
  • Theorem 5.2: $g$-eviction security of Algorithm \ref{['alg:adTx:AA:framework']}