CoW Swap Hack

TOTAL LOST $160K
Low Other

Summarize with AI

ChatGPT Perplexity Claude Grok
Affected Chain 2023 Incident surface
Recovered - No recovery reported
All-Time Rank #1376 By amount stolen
Protocol Type DEX Aggregator Target category

Incident Overview

Quick Summary

On Feb. 7, the CoW Swap fee manager contract was drained of worth 160k $USD.

Details of the Exploit

The CoW Swap uses external resolvers for swap routing to find the best exchange way. The solver also receives a protocol fee. granted approval for the malicious contract.

27 Feb the malicious contract was approved by the whitelisted solver. After that, the hacker received an opportunity to drain the fee collector contract.

Block Data Reference

Exploit TX:

https://etherscan.io/tx/0x90b46860…24379b

Malicious call:

https://etherscan.io/tx/0x92f906bc…b3bfc1

Exploiter:

https://etherscan.io/address/0xc0e82c1e…5266ff

https://etherscan.io/address/0x94b6f400…95658c

Incident Report

Protocol / Project CoW Swap
Date of Incident
Attack Technique Other
Classification Exchange (DEX)
Primary Source View Post-Mortem #1 View Post-Mortem #2

Protocol Information

Protocol Type DEX Aggregator
Official Website cow.fi/
Protocol Twitter/X @CoWSwap
Team Anonymous
Source Code Unverified

Market Context at Time of Hack

Token Categories
Privacy Ethereum Ecosystem Avalanche Ecosystem Polygon Ecosystem Arbitrum Ecosystem BNB Chain Ecosystem Optimism Ecosystem zkSync Era Ecosystem
Protocol Links
Discord Reddit

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 CoW Swap's contract logic - root cause: exchange (dex)
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 CoW Swap, these are the critical security checks that could have prevented this incident (February 2023).

  • 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

Master these auditing techniques with hands-on labs and real exploit scenarios in the Smart Contract Hacking course.

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Sources & References

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