How much was lost in the Badger DAO hack?

The Badger DAO hack resulted in $120M in losses on December 02, 2021.

What attack technique was used in the Badger DAO exploit?

The Badger DAO exploit utilized Cloudflare Key Compromised / Other. 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.

Badger DAO Hack

TOTAL LOST $120M

Critical #71 All-Time Dec 02, 2021 Cloudflare Key Compromised / Other ethereum

Affected Chain ethereum Incident surface

Recovered - No recovery reported

All-Time Rank #71 By amount stolen

Auditors 5 Prior security audits

Incident Overview

Quick Summary

BadgerDAO lost 120,000,000 $USD worth of assets due to dApp exploit

Details of the Exploit

BadgerDAO is a Yield Aggregation protocol. The attacker exploited the front end of the BadgerDAO dApp. Many impacted users alleged that while receiving yield farming rewards and engaging with Badger vaults, their wallet providers prompted them with spurious requests for extra permissions.

One of the most affected users (896 Badger WBTC):

https://etherscan.io/address/0x53461e4f…64f249

The following transaction shows that this user invokes additional approval for spending tokens for the attacker's address inside increaseAllowance() function:

https://etherscan.io/tx/0x5e4c7966…fe1f34

After that, the attacker can withdraw users' funds using transferFrom() function, for example:

https://etherscan.io/tx/0xe4e152f5…828126

Stolen funds are calculated up to $120m at the moment.

Approximately 500+ users were affected, based on the Bloxy data:

https://bloxy.info/txs/references_address/0x1fcdb04d…269107?argument=spender&signature_id=5

Block Data Reference

The attacker's address:

https://etherscan.io/address/0x1FCdb04d…269107

Incident Report

Protocol / Project Badger DAO

Date of Incident December 02, 2021

Affected Chain(s) ethereum

Attack Technique Cloudflare Key Compromised / Other

Classification Infrastructure / Yield Aggregator

Primary Source View Post-Mortem

Protocol Information

Protocol Type Yield Aggregator

Affected Token BADGER

Official Website app.badger.com/

Protocol Twitter/X @BadgerDAO

Team Anonymous

Source Code Unverified

Market Context at Time of Hack

Token Categories

DeFi DAO Ethereum Ecosystem Yield Farming Yield Aggregator Governance Blockchain Capital Portfolio Arbitrum Ecosystem

Protocol Links

Discord

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 Operational-security tradecraft (phishing, malware, leaked seed phrases, or insider access) to obtain treasury signing authority

Capital Required Minimal capital - only enough to cover gas while draining the compromised accounts

On-Chain Access Valid signing authority over the compromised wallets / multisig signers, allowing direct transfer of funds or stake authorization

Target Reconnaissance Identification of Badger DAO's high-value treasury accounts and the authority / multisig structure controlling them

Execution Speed Speed to drain the compromised accounts before the team detects the breach and revokes signing authority or freezes the assets

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 Cloudflare Key Compromised / Other audit checklist and test coverage

Audited by Audit Report 1, Audit Report 2, Audit Report 3, Audit Report 4, Audit Report 5 — still lost $120M. Prior audits don't guarantee safety, especially after post-audit code changes.

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

Verify all logic paths related to Cloudflare Key Compromised / Other 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
Audit Report 2 Report
Audit Report 3 Report
Audit Report 4 Report
Audit Report 5 Report

Sources & References

01
Source 1 https://badger.com/technical-post-mortem
02
Reference https://archive.is/TIObp

Threat Assessment

Severity Level

CRITICAL

Attack Vector Cloudflare Key Compromised / Other
Root Cause Infrastructure / Yield Aggregator
Year 2021

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