according to SlowMist monitoring, the Usual protocol encountered a complex arbitrage attack. Analysis shows that the attackers exploited the price differences between the internal mechanism of the protocol and the external market.
The core issue lies in the Usual Vault system, which allows the exchange of USD0++ and USD0 tokens at a fixed 1:1 ratio, however, these same tokens are traded at different prices on external decentralized exchanges. The attackers cleverly created a custom liquidity pool and manipulated the trading path, causing the Vault to release USD0 tokens without receiving the expected sUSDS collateral. Subsequently, the attackers sold the acquired USD0 tokens at a price higher than the internal exchange rate on the external market, thus gaining arbitrage profits.