How much was lost in the YZY DAO hack?

The YZY DAO hack resulted in $106K in losses on April 23, 2021.

What attack technique was used in the YZY DAO exploit?

The YZY DAO 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.

YZY DAO Hack

TOTAL LOST $106K

Low Apr 23, 2021 Rugpull ethereum

Affected Chain ethereum Incident surface

Recovered - No recovery reported

All-Time Rank #1513 By amount stolen

Protocol Type Exit Scam/Rugpull Target category

Incident Overview

The contract deployer transferred ownership of the vault smart contract to the external address:

https://etherscan.io/tx/0x5742ab0e…a089cb

The new owner was set as _daoTreasury in the vault smart contract:

https://etherscan.io/address/0x0a5a0a14…49d4fe#readContract

The external wallet received tokens in the form of fees. In addition, he sold them in multiple transactions:

https://etherscan.io/txsInternal?a=0xf01a9074…585302&p=1

This address removed liquidity multiple times:

https://etherscan.io/tx/0x6d64293c…e7f9c9

https://etherscan.io/tx/0x59f3ae38…0c319d

https://etherscan.io/tx/0xe481e83b…4951c0

Incident Report

Protocol / Project YZY DAO

Date of Incident April 23, 2021

Affected Chain(s) ethereum

Attack Technique Rugpull

Classification Other

Primary Source View Post-Mortem

Protocol Information

Protocol Type Exit Scam/Rugpull

Affected Token YZY

Official Website yzy.finance/

Protocol Twitter/X @yzyDAO

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

If you're auditing a protocol with similar architecture to YZY DAO, these are the critical security checks that could have prevented this incident (April 2021).

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://yzy.finance/

Threat Assessment

Severity Level

LOW

Attack Vector Rugpull
Root Cause Other
Year 2021

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