Rari Fuze hacker offered $10M bounty by Fei Protocol to return $80M loot

DeFi investigator BlockSec’s monitoring system detected a loss of more than $80 million — citing the root cause as a typical reentrancy vulnerability.

Decentralized finance (DeFi) platform Fei Protocol offered a $10 million bounty to hackers in an attempt to negotiate and retrieve a major chunk of the stolen funds from various Rari Fuse pools worth $79,348,385.61 or nearly $80 million.

On April 30, Fei Protocol informed its investors about an exploit across numerous Rari Capital Fuse pools while requesting the hackers to return the stolen funds against a $10 million bounty and a ‘no questions asked’ commitment.

We are aware of an exploit on various Rari Fuse pools. We have identified the root cause and paused all borrowing to mitigate further damage.

To the exploiter, please accept a $10m bounty and no questions asked if you return the remaining user funds.

— Fei Protocol (@feiprotocol) April 30, 2022

While the exact losses from the exploit were not officially released, DeFi investigator BlockSec’s monitoring system detected a loss of more than $80 million — citing the root cause as a typical reentrancy vulnerability. While reentrancy bugs have been the main culprit in many exploits within the DeFi ecosystem, the $80 million loot makes the Fei Protocol exploit one of the largest reentrancy hacks ever.

Upon further investigations, Rari developer Jack Longarzo revealed a total of six vulnerable pools (8, 18, 27, 127, 144, 146, 156) that have been temporarily paused while an internal fix is underway. At the time of writing, Rari’s internal and external security engineers partnered with DeFi service provider Compound Treasury to further investigate and neutralize the hack.

Providing further insights into the development, blockchain investigator PeckShield narrowed down the exploit to a reentrancy bug, which allows hackers to use a function and make external calls to another untrusted contract.

The old reentrancy bug bites again on Compound forks w/ $80M loss! This time, it re-enters via exitMarket()!!! https://t.co/NpC8AAZRXc

Watch out, all Compound forks in EVM-compliant chains. Get in touch with your auditors now or feel free to contact us if we can be of any help pic.twitter.com/M9JElTWMSd

— PeckShield Inc. (@peckshield) April 30, 2022

Security-focused ranking platform CertiK told Cointelegraph that the attacker has sent 5400 Ether (ETH) (~$15,298,900) to Tornado Cash and still holds $64,245,245.43 (22,672.97 ETH) in their wallet. The attack has drained funds from the Rari pool whilst the Fei Pools (Tribe, Curve) remain unaffected.

Last year, in May 8, 2021, Rari Capital became victim to a high-priced exploit that was related to an integration with Alpha Venture DAO (previously Alpha Finance Lab). At the time of reporting, there have been no official announcements from the Fei Protocol team on the results of their investigation.

Related: Plan for $1M bug bounties and double the nodes in wake of $600M Ronin hack

As the crypto community goes through an ever evolving battle against hackers, numerous projects and protocols have decided to amp up their security measures. On April 28, the Ronin Network and Sky Mavis revealed plans to upgrade their smart contracts — following the $600 million hack in the previous month.

We have put together a postmortem regarding the Ronin exploit that occurred on March 23rd.

• Why it happened
• What we’re doing to make sure this never happens again
• Ronin bridge re-opening updatehttps://t.co/FfwCtCG84E

— Ronin (@Ronin_Network) April 27, 2022

The Federal Bureau of Investigation (FBI) attributed the attack to North Korea-based and state-sponsored hacking group Lazurus, as it fired off a warning to other crypto and blockchain organizations.