How much was lost in the FSL hack?

The FSL hack resulted in $1.7M in losses on October 10, 2023.

What attack technique was used in the FSL exploit?

The FSL 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.

FSL Hack

TOTAL LOST $1.7M

Medium Oct 10, 2023 Rugpull

Affected Chain 2023 Incident surface

Recovered - No recovery reported

All-Time Rank #713 By amount stolen

Protocol Type Exit Scam/Rugpull Target category

Incident Overview

Quick Summary

FSL token was rugpulled by the scammer, causing a loss of 1,681,340 USD in the exit scam on PancakeSwap.

Details of the Exploit

FSL is a BEP20 token trading on PancakeSwap. On Oct 10, 2023, the deployer minted 97 million tokens of FSL and sent them to the scammer address. The scammer sell 97M FSL tokens what worth 1.68M USDT , finally swapped for BNB and sent into Tornado Cash

Block Data Reference

Deployer Address:

https://bscscan.com/address/0x281b8cb2…6B173D

Scammer Address:

https://bscscan.com/address/0x7249B903…402352

Liquidity Removal Transaction:

https://bscscan.com/tx/0x79251500…bed5c1

Tornado Cash Transactions:

https://bscscan.com/tx/0x0d7afb60…7b7dae

https://bscscan.com/tx/0x7cbba5f4…97415e

Incident Report

Protocol / Project FSL

Date of Incident October 10, 2023

Attack Technique Rugpull

Classification Token

Primary Source View Post-Mortem

Protocol Information

Protocol Type Exit Scam/Rugpull

Affected Token FSL

Team Anonymous

Source Code Unverified

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 smart contracts and deploy a custom exploit contract

Protocol Analysis Identification of the exploitable vulnerability in FSL'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 FSL, these are the critical security checks that could have prevented this incident (October 2023).

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://twitter.com/BeosinAlert/status/1711930957107007642

Threat Assessment

Severity Level

MEDIUM

Attack Vector Rugpull
Root Cause Token
Year 2023

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