Ethereum alarm clock Hack

TOTAL LOST $260K
Low Other ethereum

What happened

Quick Summary

The Ethereum Alarm Clock smart contract was exploited, leading to the theft of $260K in gas fees as of October 2022.

Details of the Exploit

Hackers exploited a bug in the Ethereum Alarm Clock smart contract code, allowing them to profit on returned gas fees from canceled transactions. They essentially called cancel functions on their contracts with inflated transaction fees, and a bug in the smart contract refunded them a greater value of gas fees than they initially paid, allowing them to pocket the difference. This has resulted in the theft of $260K in gas fees so far.

Block Data Reference

Etherscan transaction: https://etherscan.io/tx/0x4a84d087…ca4e97

Case & protocol details

Classification Other / Protocol Logic
Protocol Type Exploit/Other
Smart Contract Language Solidity

Evidence & learning

Sources and on-chain records

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