How much was lost in the Yearn Hold Finance hack?

The Yearn Hold Finance hack resulted in $17K in losses on December 09, 2020.

What attack technique was used in the Yearn Hold Finance exploit?

The Yearn Hold Finance exploit utilized Honeypot. 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.

Yearn Hold Finance Hack

TOTAL LOST $17K

Low Dec 09, 2020 Honeypot ethereum

Affected Chain ethereum Incident surface

Recovered - No recovery reported

All-Time Rank #1904 By amount stolen

Auditors 1 Prior security audit

Incident Overview

The contract owner could disable the transfer function, which restricted users in selling their tokens.

The contract deployer added initial liquidity at:

https://etherscan.io/tx/0xe7415dcb…0b9337

Liquidity was removed by the contract deployer:

https://etherscan.io/tx/0xa48abc76…31db1e

Incident Report

Protocol / Project Yearn Hold Finance

Date of Incident December 09, 2020

Affected Chain(s) ethereum

Attack Technique Honeypot

Classification Token

Primary Source View Post-Mortem

Protocol Information

Protocol Type Yield Aggregator

Affected Token YHFI

Official Website yearn.fi/

Protocol Twitter/X @yearnfi

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 honeypot and Solidity and EVM internals

Capital Required Seed capital to cover gas and initial position setup

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

Protocol Analysis Identification of the exploitable vulnerability in Yearn Hold Finance's contract logic - root cause: token

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 Honeypot audit checklist and test coverage

Audited by Audit Report 1 — still lost $17K. Prior audits don't guarantee safety, especially after post-audit code changes.

If you're auditing a protocol with similar architecture to Yearn Hold Finance, these are the critical security checks that could have prevented this incident (December 2020).

Verify all logic paths related to Honeypot 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://twitter.com/CaptainJackAPE/status/1336646559170134017

Threat Assessment

Severity Level

LOW

Attack Vector Honeypot
Root Cause Token
Year 2020

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