Ethereum alarm clock Hack

TOTAL LOST $219K
Low Other

Summarize with AI

ChatGPT Perplexity Claude Grok
Affected Chain 2022 Incident surface
Recovered - No recovery reported
All-Time Rank #1262 By amount stolen
Protocol Type Exploit/Other Target category

Incident Overview

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

Incident Report

Protocol / Project Ethereum alarm clock
Date of Incident
Attack Technique Other
Classification Other
Primary Source View Post-Mortem #1 View Post-Mortem #2 View Post-Mortem #3

Protocol Information

Protocol Type Exploit/Other
Team Anonymous
Source Code Unverified

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.

Technical Knowledge Deep understanding of other and Solidity and EVM internals
Capital Required Seed capital to cover gas and initial position setup
On-Chain Access Ability to interact with smart contracts and deploy a custom exploit contract
Protocol Analysis Identification of the exploitable vulnerability in Ethereum alarm clock's contract logic - root cause: other
Execution Speed Precise transaction ordering and timing to exploit the vulnerability within a single atomic block
Obfuscation Plan A strategy to launder and move stolen funds - typically through mixers, cross-chain bridges, or decentralized DEX swaps to resist tracing

What Auditors Should Check

Could this have been caught in audit? Likely — with a thorough Other audit checklist and test coverage

If you're auditing a protocol with similar architecture to Ethereum alarm clock, these are the critical security checks that could have prevented this incident (October 2022).

  • 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

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Sources & References

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