What happened
On April 12, 2024, an attacker exploited a reentrancy flaw in Sumer Money's Base sdrETH market. The attack used a Balancer flash loan to manipulate the sdrETH exchange rate during repayment, then borrowed assets from the sdrcbETH and sdrUSDC markets. Contemporary technical accounts put the resulting loss or profit at about 310,000 dollars, while the snapshot rounds the incident to 350,000 dollars.
How it happened
- The attacker borrowed 150 WETH and 645,000 USDC in a Balancer flash loan and used them in the sdrETH and sdrUSDC markets.
- After borrowing the available ETH in the sdrETH market, the attacker repaid it with one wei of excess value through repayBorrowBehalf.
- That function refunded the excess through a low-level external call before totalBorrows was updated, allowing the attacker's fallback to re-enter and inflate the sdrETH exchange rate.
- The inflated collateral value let the attacker borrow assets from the sdrcbETH and sdrUSDC markets, redeem the original position, and repay the flash loan.
Protocol details
Classification
Borrowing and Lending / Reentrancy
Protocol Type
Lending
Implementation language
Solidity
Protocol links
Website
@SumerMoney
Security review history
- CertiK View report
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