Mitigating the blind signing vulnerability in ethereum wallets

Abstract

In 2025, the largest cryptocurrency heist in history cost Bybit $1.5 billion because of a flaw known as blind signing. Essentially, cryptocurrency wallets ask users to sign transactions that look like gibberish code, so users often approve them based on trust and habit rather than real understanding. Attackers can exploit this by changing transaction details behind the scenes while keeping the on-screen transaction looking correct. In my project, I tackle this vulnerability in an Ethereum multi-signature wallet setting where multiple people must approve the same transaction. I first build a web-based simulation of the Bybit attack to understand how transaction swapping can mislead signers. Next, I implement four safety features across the transaction lifecycle: (1) Metadata validation to show the actual details of the transaction that is being signed, (2) Transaction simulation to preview what will happen to the funds, (3) Backend integrity verification to ensure the signed transaction has not been altered, and (4) Address whitelisting of approved destination addresses. My evaluation results show that these defences add negligible computational overhead, but they increase the time a user spends reviewing and confirming a transaction. To balance security with day-to-day usability, I propose an adaptive security approach that uses all defences for large, infrequent transactions, and a lightweight defence model for small, routine payments.