AST Token Incorrect Transfer Logic When Removing Liquidity

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Generic BSC Chain

The AST token, launched on the Binance Smart Chain on January 17, 2025, was exploited due to a vulnerability in its smart contract. The issue involved the removal of liquidity from the PancakeSwap pair, which resulted in a decrease in the AST token balance rather than increasing the user's balance. A hacker took advantage of this flaw by exchanging a large amount of USDT for AST, draining around $65k from the liquidity pool by exploiting the token’s transfer logic. The attacker transferred the funds to Tornado.Cash. The exploit was detected and monitored by SlowMist, TenArmorAlerts, and Nick L Franklin, who published further information. It is unclear who runs the AST token and whether any assistance has been made available for affected users.

About AST on BSC

The AST token was launched on the Binance Smart Chain on January 17th.

The Reality

Unfortunately the smart contract was launched with a vulnerability which could be exploited by removing liquidity. When remove liquidity from pancake pair, AST token decreases pancake pair balance and burn tokens of pancake pair, not increase user's balance. This means AST token balance of pancake pair decreased 2 times.

What Happened

An attacker exploited the vulnerability and made a profit of $65k.

Key Event Timeline - AST Token Incorrect Transfer Logic When Removing Liquidity

Date	Event	Description
January 17th, 2025 4:31:22 AM MST	AST Token Launched	The AST token is launched on the Binance Smart Chain.
January 21st, 2025 9:00:12 AM MST	AST Token Exploited	The AST token smart contract is exploited, netting the attacker roughly $65k.
January 21st, 2025 9:28:00 AM MST	TenArmorAlert Tweet	TenArmorAlert posts a tweet with some details of the transaction.
January 21st, 2025 6:20:00 PM MST	SlowMist Tweet Posted	SlowMist posts a tweet that they have "detected potential suspicious activity related to $AST".
January 21st, 2025 7:03:00 PM MST	Nick L Franklin Analysis	Nick L Franklin shared an analaysis of the exploit on Twitter/X.

Technical Details

"AST token on BSC was hacked because of wrong transfer logic. When remove liquidity from pancake pair, AST token decreases pancake pair balance and burn tokens of pancake pair, not increase user's balance. This means AST token balance of pancake pair decreased 2 times."

"Hacker exchanged a huge amount of USDT to AST, small amount of AST remained in pancake pair. Then, he transferred some USDT and AST to pancake pair, and called "skim", AST balance of pancake pair decreased to 1. Then, he was able to drain all USDT using a few AST tokens. He gained $65k."

Total Amount Lost

SlowMist: "Amount of loss: $ 64,700"

Nick L Franklin: $65k.

The total amount lost has been estimated at $65,000 USD.

Immediate Reactions

"According to monitoring by the SlowMist security team, AST was allegedly attacked on BSC."

"SlowMist Security Alert We detected potential suspicious activity related to $AST. As always, stay vigilant!"

Ultimate Outcome

"The attacker has transferred the funds to Tornado.Cash."

Total Amount Recovered

The total amount recovered is unknown.

What funds were recovered? What funds were reimbursed for those affected users?

Ongoing Developments

What parts of this case are still remaining to be concluded?

Individual Prevention Policies

No specific policies for individual prevention have yet been identified in this case.

For the full list of how to protect your funds as an individual, check our Prevention Policies for Individuals guide.

Platform Prevention Policies

Policies for platforms to take to prevent this situation have not yet been selected in this case.

For the full list of how to protect your funds as a financial service, check our Prevention Policies for Platforms guide.

Regulatory Prevention Policies

No specific regulatory policies have yet been identified in this case.

For the full list of regulatory policies that can prevent loss, check our Prevention Policies for Regulators guide.