Incident Overview
Bad actors took advantage of a flaw in the connection between the MasterChef contract and the SyrupBar contract. Previously, when CAKE was staked, an equivalent number of SYRUP tokens were created. The SYRUP tokens would be burnt once the CAKE was unstaked and withdrawn. The exact attack here was that if a user invoked the MasterChef contract's emergencyWithdraw method to withdraw their staked CAKE, the related SYRUP tokens were not burned as planned. This enabled malicious actors to mint additional SYRUP tokens using their CAKE tokens on a regular basis.
Because there were much more SYRUP tokens in circulation than was permitted, the bad actors received a larger share of Syrup Pool rewards.
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 PancakeSwap, these are the critical security checks that could have prevented this incident (November 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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