How much was lost in the MoltenSwap hack?

The MoltenSwap hack resulted in $122K in losses on March 07, 2021.

What attack technique was used in the MoltenSwap exploit?

The MoltenSwap 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.

MoltenSwap Hack

TOTAL LOST $122K

Low Mar 07, 2021 Rugpull binance

Affected Chain binance Incident surface

Recovered - No recovery reported

All-Time Rank #1458 By amount stolen

Protocol Type Exit Scam/Rugpull Target category

Incident Overview

The Master Chef contract contains hidden functionality under the set() function, which was invoked multiple times by the contract deployer at:

https://explorer.bitquery.io/bsc/txs/calls?internal=false&contract=0xb9c56744…3e7070&method=d9638422

Calling set() function led to the LP tokens transfer onto the external wallet, example transaction:

https://bscscan.com/tx/0x3b8ed32a…53de91 (at the bottom of the list)

The liquidity was removed by the external wallet multiple times at:

https://bscscan.com/tx/0x31c99d77…e84d55

https://bscscan.com/tx/0xde655409…4887cc

https://bscscan.com/tx/0x6c9d7e8b…e4de6b

https://bscscan.com/tx/0x21d2c374…e69a10

https://bscscan.com/tx/0x3a0c56b9…8cb1bb

https://bscscan.com/tx/0xdcd892c2…81b640

https://bscscan.com/tx/0x9033ed6a…9f1865

https://bscscan.com/tx/0x0deb3c97…d73e5e

https://bscscan.com/tx/0x53a1f15d…7da8e0

Incident Report

Protocol / Project MoltenSwap

Date of Incident March 07, 2021

Affected Chain(s) binance

Attack Technique Rugpull

Classification Exchange (DEX)

Protocol Information

Protocol Type Exit Scam/Rugpull

Affected Token MOLT

Official Website www.unidex.exchange

Protocol Twitter/X @UniDexFinance

Market Context at Time of Hack

Token Categories

Privacy Ethereum Ecosystem Fantom Ecosystem Arbitrum Ecosystem Optimism Ecosystem zkSync Era Ecosystem Base Ecosystem Blast 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 rugpull and Solidity and EVM internals

Capital Required Seed capital to cover gas and initial position setup

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

Protocol Analysis Identification of the exploitable vulnerability in MoltenSwap'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? Hard to catch — private key / OpSec failures are outside smart contract audit scope

If you're auditing a protocol with similar architecture to MoltenSwap, these are the critical security checks that could have prevented this incident (March 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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Threat Assessment

Severity Level

LOW

Attack Vector Rugpull
Root Cause Exchange (DEX)
Year 2021

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