How much was lost in the Focus hack?

The Focus hack resulted in $10K in losses on February 28, 2021.

What attack technique was used in the Focus exploit?

The Focus exploit utilized Rugpull. 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.

Focus Hack

TOTAL LOST $10K

Low Feb 28, 2021 Rugpull ethereum

Affected Chain ethereum Incident surface

Recovered - No recovery reported

All-Time Rank #1945 By amount stolen

Protocol Type Exit Scam/Rugpull Target category

Incident Overview

The contract deployer added initial liquidity at:

https://etherscan.io/tx/0x7a2a205e…256347

The part of tokens was transferred to some external wallet by the contract deployer:

https://etherscan.io/tx/0xb0f55eaa…0f0134

The tokens were sold by the recipient in the following transactions:

https://bloxy.info/txs/transfers_from/0x2933df4f…a41750?currency_id=643498

The liquidity was removed by the contract deployer at:

https://etherscan.io/tx/0xd0359495…2011a9

Incident Report

Protocol / Project Focus

Date of Incident February 28, 2021

Affected Chain(s) ethereum

Attack Technique Rugpull

Classification Token

Primary Source View Post-Mortem

Protocol Information

Protocol Type Exit Scam/Rugpull

Affected Token FCS

Official Website focus-defi.com/

Protocol Twitter/X @vaultzdefi

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 rugpull 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 Focus's contract logic - root cause: token

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? Hard to catch — private key / OpSec failures are outside smart contract audit scope

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

Verify all logic paths related to Rugpull 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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Sources & References

01
Source 1 https://focus-defi.com/

Threat Assessment

Severity Level

LOW

Attack Vector Rugpull
Root Cause Token
Year 2021

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