What happened
Around 3:00 a.m. UCT + 8 on April 5, 2021, the smart contract of Polkatrain was attacked by hackers during the LBP auction, 57000 DOT were stolen in the contract and turned away.
The LBP contract has a swap function and a rebate mechanism. When users buy PLOT tokens through the swap function, they get a certain amount of rebates, and the rebates will be It is sent to the user by calling transferFrom in the _update function in the contract. Since the _update function does not set the maximum amount of rebates in a pool, nor does it determine whether the total rebates are used up when rebates, malicious arbitrageurs can continue to call the swap function to exchange tokens to get the contract.
Case & protocol details
Evidence & learning
Sources and on-chain records
- report Report polkatrain.medium.com
- report Report hacked.slowmist.io
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