Incident Overview
On April 23, 2025, the ACB token on BNB Chain was exploited through an airdrop vulnerability, resulting in losses of approximately $60,000.
The attacker, funded via Tornado Cash, exploited a vulnerability in the ACB token’s airdrop mechanism that allowed them to claim rewards multiple times, draining the airdrop contract. The exploit involved abusing a cash exploit flaw without proper eligibility or duplication checks. After successfully extracting around $60,000, the attacker moved the stolen funds back to Tornado Cash to obfuscate their trail.
The compromised contract was a proxy pointing to a vulnerable implementation contract, and the exploit has been confirmed as fully executed.
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 ACB, these are the critical security checks that could have prevented this incident (April 2025).
- 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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The ACB hack is one of many attacks that skilled auditors are trained to detect before deployment. Master real exploit patterns and defense techniques with hands-on Web3 security training.