SUI ecosystem project Cetus suffered a $230 million attack, detailed methods and flow of funds.

On May 22, the liquidity provider Cetus on the SUI ecosystem was allegedly attacked, resulting in a significant decrease in liquidity pool depth and a drop in several token trading pairs, with estimated losses exceeding $230 million. Cetus subsequently announced that it has suspended the smart contract and is investigating the incident.

A certain security team quickly intervened to analyze and issued a security alert. Below is a detailed analysis of the attack methods and the funds transfer situation.

Attack Analysis

The core of this attack lies in the attackers carefully constructing parameters, allowing the overflow to occur while bypassing detection, ultimately exchanging a minimal amount of tokens for a substantial amount of liquidity assets. The specific steps are as follows:

1. The attacker first borrowed a large amount of haSUI through a flash loan, causing the pool price to plummet by 99.90%.

2. The attacker chose a very narrow price range to establish a liquidity position, with a range width of only 1.00496621%.

3. Attack Core: The attacker claims to add a huge amount of liquidity, but the system actually only received 1 token A. This is due to an overflow detection bypass vulnerability in the checked_shlw function within the get_delta_a function.

4. The attacker removes liquidity and gains huge token profits.

5. The attacker returned the flash loan, netting approximately 10,024,321.28 haSUI and 5,765,124.79 SUI.

Project Party Fix

Cetus has released a patch that primarily fixes the implementation of the checked_shlw function:

• Correct the incorrect mask to the correct threshold
• Correct judgment conditions
• Ensure that the overflow flag can be correctly detected and returned.

Capital Flow Analysis

The attacker profited approximately $230 million, including various assets such as SUI, vSUI, and USDC. The attacker transferred part of the funds to EVM addresses via cross-chain bridges. Specific actions include:

• Cross-chain some assets like USDC, SOL, suiETH to EVM addresses
• Transfer approximately 5.2341 WBNB across chains to BSC address
• Deposit assets worth $10 million into Suilend.
• Transfer 24,022,896 SUI to the new address

According to Cetus, a total of $162 million in stolen funds has been successfully frozen on SUI.

On EVM chains, the actions of attackers include:

• Received and held approximately 5.2319 BNB on BSC
• Receive and exchange multiple tokens for ETH on Ethereum
• Transfer 20,000 ETH to the new address
• The current balance on Ethereum is 3,244 ETH

Summary

This attack demonstrates the dangers of mathematical overflow vulnerabilities. The attacker exploited the flaw in the checked_shlw function by making precise calculations and choosing specific parameters, obtaining massive liquidity at a very low cost. Developers should strictly validate the boundary conditions of all mathematical functions in smart contract development to prevent similar vulnerabilities.