Sonne Finance (2024) — Crypto Hack
Partially RecoveredSonne Finance, a Compound v2 fork on Optimism, was exploited for ~$20M through a reentrancy vulnerability in its lending markets.
Summary
Sonne Finance, a Compound v2 fork on Optimism, was exploited for ~$20M through a reentrancy vulnerability in its lending markets.
How It Was Compromised — DeFi via Smart Contract Exploit / Reentrancy
On May 20, 2024, Sonne Finance, a Compound v2 fork deployed on Optimism and Base, was exploited for approximately $20M. The attacker identified a reentrancy vulnerability in the protocol's lending markets that allowed them to manipulate collateral accounting and borrow more than their collateral should have permitted. The exploit was executed on the Optimism deployment, while the Base deployment was paused before being affected. Sonne Finance paused all markets and engaged with blockchain analytics firms to track the stolen funds.
Fund Flow & Laundering Analysis
Stolen tokens were swapped to ETH and stablecoins via decentralized exchanges on Optimism. The funds were then bridged to Ethereum mainnet and deposited into Tornado Cash. Sonne Finance offered a bounty for the return of the funds and engaged with the attacker, who returned approximately $6M worth of tokens after negotiations.