How much was lost in the Yearnspace hack?

The Yearnspace hack resulted in $34K in losses on December 01, 2020.

What attack technique was used in the Yearnspace exploit?

The Yearnspace exploit utilized Rugpull. 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.

Yearnspace Hack

TOTAL LOST $34K

Low Dec 01, 2020 Rugpull ethereum

Affected Chain ethereum Incident surface

Recovered - No recovery reported

All-Time Rank #1805 By amount stolen

Protocol Type Exit Scam/Rugpull Target category

Incident Overview

The contract deployer had permission to mint tokens as he added himself to the list of minters by invoking addMinter function:

https://etherscan.io/tx/0xb3b88155…e4583f

The owner called the mint function twice at the following transactions:

https://etherscan.io/tx/0xaa5b1712…d29eeb

https://etherscan.io/tx/0x95aac0cc…b34183

The total supply was increased by 15,000 YFS tokens. The owner obtained the YFS tokens and started exchanging them for ETH, having conducted a total of 38 transactions. The contract deployer stole 58 ETH and split this amount among some external wallets. The website is down and the Twitter account is deleted.

Incident Report

Protocol / Project Yearnspace

Date of Incident December 01, 2020

Affected Chain(s) ethereum

Attack Technique Rugpull

Classification Yield Aggregator

Primary Source View Post-Mortem

Protocol Information

Protocol Type Exit Scam/Rugpull

Affected Token YFS

Official Website yearn.space/

Protocol Twitter/X @YEARNSPACE

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 rugpull 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 Yearnspace's contract logic - root cause: yield aggregator

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? Hard to catch — private key / OpSec failures are outside smart contract audit scope

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

Verify all logic paths related to Rugpull 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

01
Source 1 https://archive.ph/wJdWM
02
de.fi Analysis https://t.me/defiyield_ann/269
03
Web Archive https://web.archive.org/web/20201123042652/https://yearn.space/

Threat Assessment

Severity Level

LOW

Attack Vector Rugpull
Root Cause Yield Aggregator
Year 2020

Learn to Prevent the Next Yearnspace

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