Incident Overview
On December 10, 2024, CloberDEX’s Liquidity Vault on the Base network was exploited through a reentrancy vulnerability in the _burn() function, resulting in the theft of approximately 133.7 ETH (~$501,279).
The exploit stemmed from the _burn() function in the Rebalancer contract, where token transfers occurred before critical state variables (pool.reserveA and pool.reserveB) were updated. This deviation from the checks-effects-interactions pattern enabled a reentrancy scenario. The attacker could repeatedly call the function, exploiting the unmodified reserve values to miscalculate withdrawal amounts and drain significant funds.
By timing interactions and re-entering the contract mid-execution, the attacker extracted 133.7 ETH without triggering immediate safeguards. In response, CloberDEX promptly contacted the attacker, requested the stolen funds be returned, and reassured users that the incident did not compromise Clober Core or threaten the integrity of the Mitosis testnet.
Attacker
https://basescan.org/address/0x012fc637…aa6025
Exploit tx
https://basescan.org/tx/0x8fcdfcde…361c04
Incident Report
Protocol Information
Market Context at Time of Hack
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 Clober, these are the critical security checks that could have prevented this incident (December 2024).
- Verify all logic paths related to Reentrancy are guarded by proper access controls and input validation - see the Reentrancy attack class for patterns
- Check that all state-changing functions follow the Checks-Effects-Interactions (CEI) pattern to prevent reentrancy and logic ordering bugs
- 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 TrialSecurity Audit History
- Audit Report 1 Report
Related Attack Classes
The technique used in this hack maps to these vulnerability classes in our security curriculum:
Sources & References
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