How much was lost in the Bancor hack?

The Bancor hack resulted in $23.5M in losses on July 09, 2018.

What attack technique was used in the Bancor exploit?

The Bancor exploit utilized 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.

Bancor Hack

TOTAL LOST $23.5M

High Jul 09, 2018 Other ethereum

Affected Chain ethereum Incident surface

Recovered - No recovery reported

All-Time Rank #208 By amount stolen

Auditors 1 Prior security audit

Incident Overview

Quick Summary

Bancor smart contracts were compromised due to a security breach in a wallet used for upgrades, leading to a loss of approximately 24,984 ETH and other tokens worth around $23.5M.

Details of the Exploit

The attacker compromised a wallet used for upgrading smart contracts and withdrew 24,984 ETH (~$12.5M) from the BNT smart contract. The same wallet was also used to steal 229,356,645 NPXS (~$1M) and 3,200,000 BNT (~$10M). The stolen funds were transferred to multiple wallets before being deposited into the Huobi exchange.

Block Data Reference

The transactions related to the attack can be traced through the following links:

- Initial withdrawal of Bancor's ETH: [Transaction Link](https://etherscan.io/tx/0xf9fe97d6…5e9bde)

- Additional ETH received by Phishing1701: [Transaction Link](https://etherscan.io/tx/0xfdb8d337…b2c833)

- Conversion of Bancor's ETH into Ether: [Transaction Link](https://etherscan.io/tx/0x43a964e6…b92ba0)

- Transfer of ETH to Phishing1702: [Transaction Link](https://etherscan.io/tx/0x4a47e32d…b62b9f)

- Transfer of ETH to Phishing1703: [Transaction Link](https://etherscan.io/tx/0x2c281aa4…7999a2)

- Transfer of ETH to the hacker's wallet: [Transaction Link](https://etherscan.io/tx/0x1890d018…c0babe)

- Transfer of ETH to an external wallet: [Transaction Link](https://etherscan.io/tx/0x49265054…63d57d)

- Deposit of ETH into the Huobi exchange: [Wallet Address](https://etherscan.io/address/0xd294ac18…220550)

Incident Report

Protocol / Project Bancor

Date of Incident July 09, 2018

Affected Chain(s) ethereum

Attack Technique Other

Classification Exchange (DEX)

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

Protocol Information

Protocol Type Lending

Affected Token BNT

Official Website bancor.network/

Protocol Twitter/X @Bancor

Team Anonymous

Source Code Unverified

Market Context at Time of Hack

Token Categories

Marketplace Decentralized Exchange (DEX) Token DeFi Payments Scaling Ethereum Ecosystem AMM Solana Ecosystem

Protocol Links

GitHub 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 other 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 Bancor's contract logic - root cause: exchange (dex)

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? Likely — with a thorough Other audit checklist and test coverage

Audited by Audit Report 1 — still lost $23.5M. Prior audits don't guarantee safety, especially after post-audit code changes.

If you're auditing a protocol with similar architecture to Bancor, these are the critical security checks that could have prevented this incident (July 2018).

Verify all logic paths related to 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.

Free Trial

Security Audit History

Audit Report 1 Report

Sources & References

01
Source 1 https://medium.com/sentinel-protocol/over-25-000-eth-from-bancor…
02
Source 2 https://techcrunch.com/2018/07/10/bancor-loses-23-5m/?guccounter…

Threat Assessment

Severity Level

HIGH

Attack Vector Other
Root Cause Exchange (DEX)
Year 2018

Learn to Prevent the Next Bancor

The Bancor hack is one of many attacks that skilled auditors are trained to detect before deployment. Master real exploit patterns and defense techniques with hands-on Web3 security training.

Start Free Trial Browse Attack Library