A Blockchain Name System (BNS) simplifies the process of sending cryptocurrencies by replacing complex cryptographic recipient addresses with human-readable names, making the transactions more convenient. Unfortunately, these names can be susceptible to typosquatting attacks, where attackers can take advantage of user typos by registering typographically similar BNS names. Unsuspecting users may accidentally mistype or misinterpret the intended name, resulting in an irreversible transfer of funds to an attacker's address instead of the intended recipient. In this work, we present the first large-scale, intra-BNS typosquatting study. To understand the prevalence of typosquatting within BNSs, we study three different services (Ethereum Name Service, Unstoppable Domains, and ADAHandles) spanning three blockchains (Ethereum, Polygon, and Cardano), collecting a total of 4.9M BNS names and 200M transactions-the largest dataset for BNSs to date. We describe the challenges involved in conducting name-squatting studies on these alternative naming systems, and then perform an in-depth quantitative analysis of our dataset. We find that typosquatters are indeed active on BNSs, registering more malicious domains with each passing year. Our analysis reveals that users have sent thousands of transactions to squatters and that squatters target both globally popular BNS domain names as well as the domains owned by popular Twitter/X users. Lastly, we document the complete lack of defenses against typosquatting in custodial and non-custodial wallets and propose straightforward countermeasures that can protect users without relying on third-party services.
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