Incident Overview
BvaultsBank was exploited through a flash loan attack, resulting in a loss of 8,016,006.09 BUSD.
The attacker initiated the exploit by borrowing a flash loan of 7,804,239.11 BUSD from CREAM. This was deposited into BvaultsBank and sent to the associated BvaultsStrategy strategy, then to Alpaca Vault for yield. The Alpaca Vault minted 7,598,066.58 ibBUSD back to BvaultsStrategy.
The attacker then farmed with the received ibBUSD via the Alpaca FairLaunch. The attacker withdrew the BUSD from BvaultsBank, which was interpreted as withdrawing ibBUSD, equivalent to 8,016,006.09 BUSD. The attacker repeated these steps to accumulate credit and finally drained the pool.
The flash loan was returned with 7,806,580.38 BUSD.
The attacker's address:
https://bscscan.com/address/0x47f341d8…50d089
The transaction behind the attack:
https://bscscan.com/tx/0x603b2bbe…d9a36c
Incident Report
Protocol Information
What the Attacker Needed to Succeed
Understanding the prerequisites for this type of attack helps auditors identify protocols that are most at risk and helps developers build better defenses.
What Auditors Should Check
If you're auditing a protocol with similar architecture to bEarn Fi, these are the critical security checks that could have prevented this incident (May 2021).
- Verify all logic paths related to Flash Loan Attack are guarded by proper access controls and input validation - see the Flash Loans Attacks attack class for patterns
- Review privileged functions (owner, admin, governance) for potential abuse vectors - centralization risks should be documented and bounded with timelocks or multi-sigs
Master these auditing techniques with hands-on labs and real exploit scenarios in the Smart Contract Hacking course.
Free TrialRelated Attack Classes
The technique used in this hack maps to these vulnerability classes in our security curriculum:
Sources & References
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