Incident Overview
Two vFarms were exploited:
50% IRON — 50% SIL
50% IRON — 50% BUSD
A user who farmed in these two pools claimed all SIL rewards allocated for farming over the next 12 months and made a profit of around $170K by selling SIL for BUSD on vSwap.
Value DeFi team has upgraded FaaS, in which the reward rate is in normal integer instead of Ggwei as before. Iron.Finance team was unaware of the change and updated Iron vFarm pools with reward rate in Gwei. This caused the pools' rewards to inflated by 10^18 times.
The following address took advantage of the mistake and drained all SIL rewards and sold them to the market:
https://bscscan.com/address/0x69655181…63e9e5#tokentxns
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 Iron Finance, these are the critical security checks that could have prevented this incident (March 2020).
- Verify all logic paths related to Other are guarded by proper access controls and input validation
- 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.
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