RedSonic Vault Flash Loan Attack Drains 9.25 ETH via Dual-Asset Flaw

A flash loan attack on Ethereum's RedSonic Vault drained the platform of 9.25 ETH, according to blockchain security firm ExVulSec. The attacker exploited a dual-asset pricing flaw in the vault's design, which allowed them to artificially inflate the share price and cash out.

The exploit involved registering stETH as a second asset class, creating a new rsvstETH share type that drew from the same underlying stETH balance. This created a situation where the vault's raw stETH balance could be manipulated without minting or burning corresponding shares.

The attacker deposited 1,130 ETH first, acquiring nearly 99% of all outstanding rsvETH shares. They then deposited 9.34 stETH into the vault, inflating the share price and increasing the value of their existing rsvETH holdings. The attacker redeemed the shares for 1,139.5 ETH, generating a profit of 9.25 ETH.