How much was lost in the OneRing hack?

The OneRing hack resulted in $1.5M in losses on March 21, 2022.

What attack technique was used in the OneRing exploit?

The OneRing exploit utilized Flash Loan Attack. 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.

OneRing Hack

TOTAL LOST $1.5M

Medium Mar 21, 2022 Flash Loan Attack

Affected Chain 2022 Incident surface

Recovered - No recovery reported

All-Time Rank #731 By amount stolen

Protocol Type Yield Target category

Incident Overview

The attacker's wallet:

https://ftmscan.com/address/0x12efed35…ce905e

The exploit contract:

https://ftmscan.com/address/0x6a6d593e…0b5a58

The transaction behind the attack:

https://ftmscan.com/tx/0xca8dd338…a70145

The attack was enabled via a flash loan-assisted price manipulation of the LP tokens, which resulted in a greater quantity of OShare tokens being removed from the protocol.

After the contract deployment, the hacker borrowed $80m USDC utilizing Solidly flash loans to boost the price of our underlying LP tokens in a single block, changing the price of OShare and driving a huge number of OShare tokens out of the protocol.

Stolen funds were bridged to Ethereum and deposited into Tornado Cash mixer:

https://etherscan.io/address/0x12efed35…ce905e

This is classified as a Flash Loans Attacks . Compare similar hacks →

Incident Report

Protocol / Project OneRing

Date of Incident March 21, 2022

Attack Technique Flash Loan Attack

Classification Yield Aggregator

Primary Source View Post-Mortem #1 View Post-Mortem #2

Protocol Information

Protocol Type Yield

Affected Token RING

Official Website www.onering.finance/

Protocol Twitter/X @Onering_Finance

Team Anonymous

Source Code Unverified

Market Context at Time of Hack

Token Categories

Fantom 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 Deep understanding of flash loan attack and Solidity and EVM internals

Capital Required Flash loan capital (borrowed atomically, zero upfront cost)

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

Protocol Analysis Identification of the exploitable vulnerability in OneRing'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? Yes — skilled auditors routinely flag Flash Loan Attack vulnerabilities in code review

If you're auditing a protocol with similar architecture to OneRing, these are the critical security checks that could have prevented this incident (March 2022).

Verify all logic paths related to Flash Loan Attack are guarded by proper access controls and input validation - see the Flash Loans Attacks attack class for patterns
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 Flash Loans Attacks examples →

Flash Loans Attacks

Sources & References

01
Source 1 https://medium.com/oneringfinance/onering-finance-exploit-post-m…
02
Source 2 https://twitter.com/peckshield/status/1506090607059431427

Threat Assessment

Severity Level

MEDIUM

Attack Vector Flash Loan Attack
Root Cause Yield Aggregator
Year 2022

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