How much was lost in the Ola Finance hack?

The Ola Finance hack resulted in $4.0M in losses on March 31, 2022.

What attack technique was used in the Ola Finance exploit?

The Ola Finance exploit utilized Reentrancy / 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.

Ola Finance Hack

TOTAL LOST $4.0M

Medium Mar 31, 2022 Reentrancy / Other fuse

Affected Chain fuse Incident surface

Recovered - No recovery reported

All-Time Rank #472 By amount stolen

Auditors 1 Prior security audit

Incident Overview

The attacker's address:

https://explorer.fuse.io/address/0x371D7C9e…D63d75/transactions

The example transaction behind the exploit:

https://explorer.fuse.io/tx/0x1b3e06b6…b1dc90/token-transfers

The hack is made possible by the incompatibility between the Compound fork and ERC677/ERC777-based tokens, which have the built-in callback functions exploited to allow for reentry in doTransferOut() function and draining of the loan pool.

The attacker was initially funded by Tornado in Ethereum:

https://etherscan.io/tx/0x98c46fc9…a24efb

After the exploit execution, funds were delivered back into Ethereum and transferred to the following wallet:

https://etherscan.io/address/0xbcdb800d…118f42

This is classified as a Reentrancy . Compare similar hacks →

Incident Report

Protocol / Project Ola Finance

Date of Incident March 31, 2022

Affected Chain(s) fuse

Attack Technique Reentrancy / Other

Classification Smart Contract Language / Borrowing and Lending

Primary Source View Post-Mortem

Protocol Information

Protocol Type CDP

Smart Contract Language Solidity

Official Website ola.finance/

Protocol Twitter/X @ola_finance

Team Anonymous

Source Code Unverified

Market Context at Time of Hack

Token Categories

Solana Ecosystem

Protocol Links

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 reentrancy / other and Solidity and EVM internals

Capital Required Seed capital to cover gas and initial position setup

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

Protocol Analysis Identification of the exploitable vulnerability in Ola Finance's contract logic - root cause: smart contract language / 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 Reentrancy / Other vulnerabilities in code review

Audited by Audit Report 1 — still lost $4.0M. Prior audits don't guarantee safety, especially after post-audit code changes.

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

Verify all logic paths related to Reentrancy / Other are guarded by proper access controls and input validation - see the Reentrancy attack class for patterns
Check that all state-changing functions follow the Checks-Effects-Interactions (CEI) pattern to prevent reentrancy and logic ordering bugs
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

Related Attack Classes

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

See all Reentrancy examples →

Reentrancy

Sources & References

01
Source 1 https://www.coindesk.com/tech/2022/03/31/ola-finance-exploited-f…
02
Reference https://twitter.com/ola_finance/status/1509431464521256961
03
Reference https://twitter.com/peckshield/status/1509431646818234369

Threat Assessment

Severity Level

MEDIUM

Attack Vector Reentrancy / Other
Root Cause Smart Contract Language / Borrowing and Lending
Year 2022

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