Incident Overview
On January 21, 2025, the AST token on the Binance Smart Chain (BSC) was exploited, resulting in a loss of approximately $64,700 in USDT.
The exploit targeted a vulnerability in the AST token’s _transfer function during liquidity removal scenarios on PancakeSwap. When liquidity was removed, the logic incorrectly reduced the pair’s AST balance twice, creating an abnormally low reserve. This imbalance allowed the attacker to manipulate the automated market maker's pricing formula, enabling them to swap a small amount of AST for a disproportionately large amount of USDT.
The attacker repeatedly triggered this scenario by transferring small LP tokens to initiate liquidity removal, ultimately draining approximately $64.7K USDT, which was then funneled through Tornado Cash.
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 AST Token, these are the critical security checks that could have prevented this incident (January 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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