blockchainmedium

Token to Wonderland

hackthebox

Task: Buy Golden Key from Shop contract with only 100 SVC tokens when price is 25,000,000. Solution: Exploit integer underflow in Solidity 0.7.x ERC20 token where transfer() skips balance check, causing balance to wrap to 2^256-1, then approve and purchase.

$ ls tags/ techniques/
integer_underflowevm_bytecode_reverseerc20_balance_manipulationdual_transfer_implementation

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