How much was lost in the Clipper hack?

The Clipper hack resulted in $450K in losses on December 01, 2024.

What attack technique was used in the Clipper exploit?

The Clipper exploit utilized API Signature Exploit. Understanding this attack vector is critical for smart contract auditors and developers building secure DeFi protocols.

How can developers prevent similar smart contract attacks?

Preventing smart contract hacks requires a combination of secure coding practices, thorough security audits, and understanding common attack vectors like reentrancy, oracle manipulation, and access control flaws. Smart Contract Hacking (SCH) provides hands-on training to help developers and auditors identify and prevent vulnerabilities before deployment.

Clipper Hack

TOTAL LOST $450K

Low Dec 01, 2024 API Signature Exploit base optimism

Affected Chain base 2 chains affected

Recovered - No recovery reported

All-Time Rank #1042 By amount stolen

Auditors 1 Prior security audit

Incident Overview

Clipper is the decentralized exchange (DEX) built to give the self-made crypto trader the best possible prices on small trades (< $10k)

Incident Report

Protocol / Project Clipper

Date of Incident December 01, 2024

Affected Chain(s) base optimism

Attack Technique API Signature Exploit

Classification Protocol Logic

Primary Source View Post-Mortem

Protocol Information

Protocol Type Dexs

Official Website clipper.exchange

Protocol Twitter/X @Clipper_DEX

Market Context at Time of Hack

Token Categories

Polygon Ecosystem

Protocol Links

GitHub 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 api signature exploit and Solidity and EVM internals

Capital Required Seed capital to cover gas and initial position setup

On-Chain Access Ability to interact with base, optimism smart contracts and deploy a custom exploit contract

Protocol Analysis Identification of the exploitable vulnerability in Clipper's contract logic - root cause: protocol logic

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 API Signature Exploit audit checklist and test coverage

Audited by Audit Report 1 — still lost $450K. Prior audits don't guarantee safety, especially after post-audit code changes.

If you're auditing a protocol with similar architecture to Clipper, these are the critical security checks that could have prevented this incident (December 2024).

Verify all logic paths related to API Signature Exploit 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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Security Audit History

Audit Report 1 Report

Sources & References

01
Source 1 https://x.com/Clipper_DEX/status/1863263893470003460

Threat Assessment

Severity Level

LOW

Attack Vector API Signature Exploit
Root Cause Protocol Logic
Year 2024

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