How much was lost in the Venus hack?

The Venus hack resulted in $77.0M in losses on May 18, 2021.

What attack technique was used in the Venus exploit?

The Venus exploit utilized Oracle Issue. 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.

Venus Hack

TOTAL LOST $77.0M

High #98 All-Time May 18, 2021 Oracle Issue

Affected Chain 2021 Incident surface

Recovered - No recovery reported

All-Time Rank #98 By amount stolen

Protocol Type Exploit/Oracle Issue Target category

Incident Overview

Quick Summary

The Venus Protocol experienced a massive liquidation event, due to market circumstances and oracle problems

Details of the Exploit

Venus Protocol is an algorithmic-based money market system, that offers lending opportunities on Binance Smart Chain. The project experienced a big liquidation event. In comparison, the 0xef044206db68e40520 bfa82d45419d498b4bc7bf account lost about $66 million in net loss. Liquidators earned around $20 million profit; Sellers made approximately $55 million profit, and Scalpers made approximately $2 million profit.

Due to unpredictable market fluctuations and the lack of deviation controls on oracles, the protocol lost about $77 million.

Block Data Reference

Token address:

https://bscscan.com/address/0xcf6bb538…626c63

This is classified as a Oracle Manipulation & Price Manipulation . Compare similar hacks →

Incident Report

Protocol / Project Venus

Date of Incident May 18, 2021

Attack Technique Oracle Issue

Classification Borrowing and Lending

Primary Source View Post-Mortem

Protocol Information

Protocol Type Exploit/Oracle Issue

Affected Token XVS

Official Website venus.io/

Protocol Twitter/X @VenusProtocol

Team Anonymous

Source Code Unverified

Market Context at Time of Hack

Token Categories

DeFi Ethereum Ecosystem Yield Farming Binance Launchpool Lending & Borrowing Arbitrum Ecosystem BNB Chain Ecosystem Optimism 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 oracle issue 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 Venus's contract logic - root cause: borrowing and lending

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? Yes — skilled auditors routinely flag Oracle Issue vulnerabilities in code review

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

Verify all logic paths related to Oracle Issue are guarded by proper access controls and input validation - see the Oracle Manipulation & Price Manipulation attack class for patterns
Audit oracle price feeds for manipulation risks - ensure time-weighted average prices (TWAPs) or multi-source aggregators are used, not spot prices
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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Related Attack Classes

The technique used in this hack maps to these vulnerability classes in our security curriculum:

See all Oracle Manipulation & Price Manipulation examples →

Oracle Manipulation & Price Manipulation

Sources & References

01
Source 1 https://archive.is/hf1Ue

Threat Assessment

Severity Level

HIGH

Attack Vector Oracle Issue
Root Cause Borrowing and Lending
Year 2021

Learn to Prevent the Next Venus

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