Underline: students advised by Dr. Tang
USENIX Security'24: “Understanding Ethereum Mempool Security under Asymmetric DoS by Symbolized Stateful Fuzzing”, AR=14.5%, Yibo Wang, Yuzhe Tang, Kai Li, Wanning Ding, Zhihua Yang. [pdf], [slides]
Summary: mpfuzz is the first fuzzer to find unique design flaws in mempool, a security-critical component in blockchains. mpfuzz models asymmetric mempool-DoS (denial of service) attacks like DETER (CCS'21) as its bug oracles and employs a novel transaction-symbolization technique to speed up fuzzing. Instead of covering the large space of concrete Ethereum transactions, mpfuzz covers only seven symbols abstracted from the semantics of Ethereum transactions in a way that does not miss detecting bugs. mpfuzz detects more than 20 mempool DoS vulnerabitlies besides DETER, most of which are confirmed.
Euro S&P'23: “Understanding the Security Risks of Decentralized Exchanges by Uncovering Unfair Trades in the Wild”, AR=35.7%, Jiaqi Chen, Yibo Wang, Yuxuan Zhou, Wanning Ding , Yuzhe Tang, X. Wang, Kai Li. [preprint], [slides], [2-page slides]
Summary: DEX, or decentralized exchange, is a prominent class of decentralized finance (DeFi) applications on blockchains, attracting a total locked value worth tens of billions of USD today. This paper presents the first large-scale empirical study that uncovers unfair trades on popular DEX services on Ethereum and Binance Smart Chain (BSC). By joining and analyzing 60 million transactions, we find 671,400 unfair trades on all six measured DEXes, including Uniswap, Balancer, and Curve. Out of these unfair trades, we attribute 55,000 instances, with high confidence, to token thefts that cause a value loss of more than 3.88 million USD. Furthermore, the measurement study uncovers previously unknown causes of extractable value and real-world adaptive strategies to these causes. Finally, we propose countermeasures to redesign secure DEX protocols and to harden deployed services against the discovered security risks.
CCS'21: “DETER: Denial of Ethereum Txpool sERvices”, AR=22%, Kai Li, Yibo Wang, Yuzhe Tang. [pdf], [slides], [talk], [poster], [Patch@Geth-1.11.4], [CVE-2022-23327], [CVE-2022-23328]
Summary: This work examines the design security of Ethereum's txpool (or memory pool) which is a buffer storing unconfirmed transactions prior to mining. By modeling transaction operations in txpool, we discover a series of denial-of-service attacks, named DETER attacks that can disable a remote Ethereum node's txpool and deny critical services in mining and transaction relay. DETER attacks incur zero or low Ether cost, and can be extended to result in disruption to an entire Ethereum network. We propose mitigation schemes that reduce a DETER attack's success rate to zero while preserving the miners' revenue.
FSE'21: “iBatch: Saving Ethereum Fees via Secure and Cost-Effective Batching of Smart-Contract Invocations”, AR=24.5%, Yibo Wang, Qi Zhang, Kai Li, Yuzhe Tang, Jiaqi Chen, X. Luo, T. Chen. [pdf], [extended version], [html], [slides]
Summary: Today, blockchains' transaction fees are skyrocketing and have scared away some big customers (e.g., Binance as an institutional customer in Ethereum). This work tackles this pressing problem on Ethereum and presents iBatch, a security protocol to batch-process multiple smart-contract invocations in a single transaction, hence amortizing its high fees. To ensure the security (invocation integrity) while saving costs, we propose a novel nonce-maintenance method to defend against replay attacks. We design a middleware system supporting a range of batching policies from the conservative to the more aggressive batching. By replaying real Ethereum transactions, we evaluate iBatch's cost. The result shows iBatch saves 14.6%-59.1% Gas cost per invocation with a moderate 2-minute delay and 19.06%-31.52% Ether cost per invocation with a minimal delay of 0.26-1.66 blocks.
NDSS'21: “As Strong As Its Weakest Link: How to Break (and Fix) Blockchain DApps at RPC Service”, AR=15.2%, Kai Li, Jiaqi Chen, Xianghong Liu, Yuzhe Tang, X. Wang, X. Luo. [pdf], [slides], [demo1], [demo2]
Summary: This work presents a measurement study examining the security of Ethereum remote procedural call (RPC) services. The key RPC API is "eth_call", which supports free execution of smart contracts. Misusing this API leads to a zero-cost denial-of-service attack, which we call Denial of Ethereum Rpc Service (DoERS). Novel measurement methods are proposed to uncover the load balancing, rate limiting, Gas limits, and other service internal behaviors that would otherwise be hidden inside the blackbox services. The results show that at the time of measurement, most services are vulnerable to the DoERS attacks -- a DoERS attacker investing zero Ether/USD can cause severe service interruption with significant response time increase.