How much was lost in the PolBase Cash hack?

The PolBase Cash hack resulted in $354K in losses on January 07, 2021.

What attack technique was used in the PolBase Cash exploit?

The PolBase Cash 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.

PolBase Cash Hack

TOTAL LOST $354K

Low Jan 07, 2021 Rugpull ethereum

Affected Chain ethereum Incident surface

Recovered - No recovery reported

All-Time Rank #1101 By amount stolen

Protocol Type Exit Scam/Rugpull Target category

Incident Overview

Quick Summary

PolBase Cash was an algorithmic stable coin project that contained unverified smart contracts which empowered the contract deployer to withdraw funds from the operation. Investors were deprived of $350k.

Details of the Exploit

PolBase Cash an algorithmic stable coin project that boasted three coins. $PBC (PolBase Cash) was the dollar pegged stable coin. In order to enable stabilization mechanisms $PBB (PolBase Bonds) and $PBS (PolBase Share) were introduced, similar to the popular Tomb Finance protocol on the Fantom network.

The contract deployer created four smart contracts for staking $USDT, $USDC, DAI and LP tokens separately. The staking contracts were unverified, meaning the code was not visible on the block explorer for everyone to review.

The contract deployer interacted with these 4 smart contracts using function setOperation() with the below address as input data:

0x5C0D86B9…5d52eA.

This address received permission to withdraw funds from the staking smart contracts. The stolen funds were then transferred to a variety of external wallets. In addition, the liquidity from the pair was removed by this address as well:

https://etherscan.io/tx/0xbf17223d…1d62fc

Block Data Reference

USDT staking contract:

https://etherscan.io/address/0x4f2582fe…e3381b

USDC staking contract:

https://etherscan.io/address/0x2b3e2fe7…025bc3

DAI staking contract:

https://etherscan.io/address/0xa72180b8…3faf2c

LP contract:

https://etherscan.io/address/0x386e747a…8b63a9

Outgoing transactions could be found at:

https://bloxy.info/address/0x5c0d86b9…5d52ea

Incident Report

Protocol / Project PolBase Cash

Date of Incident January 07, 2021

Affected Chain(s) ethereum

Attack Technique Rugpull

Classification Stablecoin

Primary Source View Post-Mortem

Protocol Information

Protocol Type Exit Scam/Rugpull

Affected Token PBC

Official Website basis.cash/

Protocol Twitter/X @BasisCash

Team Anonymous

Source Code Unverified

Market Context at Time of Hack

Token Categories

DeFi Stablecoin Yield Farming Rebase Seigniorage

Protocol Links

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 PolBase Cash's contract logic - root cause: stablecoin

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 PolBase Cash, these are the critical security checks that could have prevented this incident (January 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://twitter.com/CaptainJackAPE/status/1347043179976003585

Threat Assessment

Severity Level

LOW

Attack Vector Rugpull
Root Cause Stablecoin
Year 2021

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