How much was lost in the Swaprum hack?

The Swaprum hack resulted in $3.0M in losses on May 19, 2023.

What attack technique was used in the Swaprum exploit?

The Swaprum exploit utilized Drained Contracts / 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.

Swaprum Hack

TOTAL LOST $3.0M

Medium May 19, 2023 Drained Contracts / Rugpull arbitrum

Affected Chain arbitrum Incident surface

Recovered - No recovery reported

All-Time Rank #548 By amount stolen

Auditors 1 Prior security audit

Incident Overview

Quick Summary

Swaprum, an Arbitrum-based DEX project, experienced a rugpull by the deployer. The total funds lost reached 2,915,567 $USD.

Details of the Exploit

Swaprum is a decentralized exchange (DEX) on the Arbitrum network with its token $SAPR. An investigation revealed that Swaprum was subjected to a rugpull by its own deployer who had privileged access to LPs in multiple pools and $SAPR token minting.

The exitscam consisted of two main parts:

1) Liquidity removals on various pools such as USDT/WETH ($241k), USDT/USDC ($280k), ARB/WETH ($280k), ARB/USDC($126K), WOM/USDT($49K) and etc.

2) Liquidity removal related to $SAPR token where initially 800k $SAPR were minted directly into scammer's wallet address followed by direct liquidity draining from SAPR/WETH pool for another 500K $SAPR tokens plus ~$94K USD worth of WETH.

Later the attacker deployed a malicious upgrade for the SAPR Controller Proxy contract which allowed to create additional 200M new $SAPR tokens out of thin air via two separate transactions.

Finally, all available liquidity in Swaprum's SAPR/WETH pool was drained using newly created tokens leaving it empty.

The total funds lost reached 2,915,567 $USD and were transferred to another EOA address in two transactions for 1,617.7 $ETH. Consequently, all the stolen funds were transferred through TornadoCash or bridged via Celer Network and Multichain Bridge.

Block Data Reference

Scammer address:

https://arbiscan.io/address/0xf2744e1f…d96627

Funds holder address:

https://arbiscan.io/address/0xaaf8b443…ef5e1c

Liquidity removal transaction examples:

https://arbiscan.io/tx/0x0ebc5f91…f0c3be

https://arbiscan.io/tx/0xcb64a40d…747edf

https://arbiscan.io/tx/0x45b911b9…d081d0

https://arbiscan.io/tx/0x33020fdf…74796a

https://arbiscan.io/tx/0x9d66bda0…3662b1

SAPR mint transactions:

https://arbiscan.io/tx/0x972dc40a…c6f541

https://arbiscan.io/tx/0x821b2e98…60168e

SAPR liquidity drain transaction example:

https://arbiscan.io/tx/0x982cc3b2…b33502

TornadoCash transfer example:

https://arbiscan.io/tx/0x8424b157…eb4eff

Incident Report

Protocol / Project Swaprum

Date of Incident May 19, 2023

Affected Chain(s) arbitrum

Attack Technique Drained Contracts / Rugpull

Classification Rugpull / Exchange (DEX)

Primary Source View Post-Mortem

Protocol Information

Protocol Type Dexs

Affected Token SAPR

Official Website swaprum.finance/

Protocol Twitter/X @Swaprum

Team Anonymous

Source Code Unverified

Market Context at Time of Hack

Token Categories

Distributed Computing Ethereum Ecosystem Storage DePIN Gnosis Chain Ecosystem

Protocol Links

GitHub Discord 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 drained contracts / rugpull and Solidity and EVM internals

Capital Required Seed capital to cover gas and initial position setup

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

Protocol Analysis Identification of the exploitable vulnerability in Swaprum's contract logic - root cause: rugpull / 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

Audited by Certik — still lost $3.0M. Prior audits don't guarantee safety, especially after post-audit code changes.

If you're auditing a protocol with similar architecture to Swaprum, these are the critical security checks that could have prevented this incident (May 2023).

Verify all logic paths related to Drained Contracts / 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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Security Audit History

Certik 2023-05-05 Report

Sources & References

01
Source 1 https://www.dlnews.com/articles/defi/defi-protocol-swaprum-in-3m…
02
Web Archive https://archive.ph/M8R0h
03
Reference https://twitter.com/DeDotFiSecurity/status/1659271879889231880

Threat Assessment

Severity Level

MEDIUM

Attack Vector Drained Contracts / Rugpull
Root Cause Rugpull / Exchange (DEX)
Year 2023

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