PISTON

Smart Contract Audit Report

Audit Summary

PISTON Audit Report PISTON is a new BEP-20 token that is an automatic liquidity providing protocol.

For this audit, we reviewed the PistonToken and PistonTokenController contracts provided to us by the project team.

Audit Findings

Please ensure trust in the team prior to investing as they have substantial control in the ecosystem.
Date: April 1st, 2022.
Updated: April 2nd, 2022 to support changes made by the project team.

Finding #1 - Piston - Informational (Resolved)

Description: Several functions are declared public, but are never called internally.
PistonToken.initialize, PistonToken.excludeMultipleAccountsFromFees, PistonToken.setAutomatedMarketMakerPair, PistonToken.isExcludedFromFees, PistonTokenController.initialize, PistonTokenController.pistonBalance, PistonTokenController.getPairBalance, PistonTokenController.getTokenAndControllerAddress
Recommendation: These functions should be declared external for additional gas savings on each call.
Resolution: The team has declared the above functions external.

Contracts Overview

  • The contracts are upgradeable, meaning the team can swap out the current contracts for new ones at any time.
  • As the contracts are implemented with Solidity v0.8.x, they are safe from any possible overflows/underflows.
PistonToken Contract:
  • The total supply of the token is currently 1 million $PSTN [1,000,000].
  • The contract utilizes a Minter role that allows the assigned address to mint any number of tokens to any account at any time.
  • The circulating supply is decreased when tokens are sent to the 0x..dead address from the PistonTokenController contract via the swapAndLiquify() function.
  • There was no token allocation for our team to analyze as the contract has yet to be deployed to the mainnet.

  • Trading must be enabled by the owner in order for all trading to take place on the platform. Only accounts that are excluded from fees can participate in transfers when trading is set to disabled.
  • The contract enforces a maximum sell amount (determined by the owner) which imposes a limit to the number of tokens that can be sold via Pancakeswap.
  • The contract enforces a maximum buy amount (determined by the owner) which imposes a limit to the number of tokens that can be bought via Pancakeswap.
  • The contract enforces a maximum wallet amount which prevents a transfer from occurring if the recipient's token balance will exceed the limit number of tokens (determined by the owner) after the transfer takes place.
  • The maximum buy amount, maximum sell amount, and maximum wallet amount restrictions do not apply to accounts that are excluded from fees.
  • There is a Liquidity fee, Ecosystem fee, and Dev fee on all transfers where neither the sender nor the recipient is excluded from fees.
  • Fees are increased by a percentage (determined by the owner) when selling tokens to Pancakeswap.
  • The tokens collected from fees are stored in the contract address. The tokens are sent to the PistonTokenController contract when the following conditions are met:
    • The automatic liquidity add functionality is enabled by the team.
    • The threshold number of tokens in the contract address (determined by the owner) has been reached.
    • The transfer is not a buy transaction via Pancakeswap.
    • Neither the sender nor the recipient is the owner or the PistonTokenController.

  • The owner can set total fees charged on transfers up to 10%.
  • The owner can update the extra sell fee when selling tokens to Pancakeswap to any value up to 15%.
  • The owner can exclude and include accounts from transfer fees.
  • The owner can disable trading at any time which will prevent all accounts that are not excluded from fees from being able to participate in transfers.
  • The owner can add/remove accounts from a blacklist that prevents users from being able to participate in transfers.
  • The owner can update the maximum buy amount, maximum sell amount, and maximum wallet amount to any values at any time.
  • The owner can enable/disable automatic liquidity adds at any time.
  • The owner can update the threshold number of tokens that triggers when tokens are sent to the PistonTokenController contract to any value.
  • The owner can update the Automated Market Maker Pair address at any time.
  • The owner can update the Pancakeswap Router address at any time.
  • The owner can update the PistonTokenController address to any address at any time.
PistonTokenController Contract:
  • The owner can call the swapAndLiquify() function at any time in order to allocate the tokens collected from fees to their respective funds.
  • The tokens collected through the Liquidity fee are swapped for BUSD for the purpose of funding Pancakeswap liquidity once the threshold number of tokens (determined by the owner) has been met.
  • Liquidity-adds are automatically performed by selling the tokens collected from the Liquidity fee, pairing the received BUSD with the token, and adding it as liquidity to the pair.
  • The LP tokens received through this process are sent to the owner. We recommend that the team lock these newly acquired LP tokens.
  • The tokens collected from the Ecosystem fee are swapped for BUSD and sent to the team's Ecosystem wallet.
  • The tokens collected from the Burn fee are sent to the 0x..dead address.
  • The remaining tokens in the contract are sent to the Race contract set by the team.
  • The owner can set the threshold number of tokens that triggers an automatic liquidity add to any value at any time.
  • The owner can set the team's Ecosystem wallet and the Race contract to any addresses at any time.

Audit Results

Vulnerability CategoryNotesResult
Arbitrary Jump/Storage WriteN/APASS
Centralization of Control
  • The assigned Minter address can mint any amount of tokens at any time.
  • The LP tokens generated through automatic liquidity adds are sent to the owner.
  • The team can upgrade the contract at any time.
  • The owner can update the PistonTokenController address to any address at any time.
  • The owner can blacklist accounts from being able to participate in transfers.
  • WARNING
    Compiler IssuesN/APASS
    Delegate Call to Untrusted ContractN/APASS
    Dependence on Predictable VariablesN/APASS
    Ether/Token TheftN/APASS
    Flash LoansN/APASS
    Front RunningN/APASS
    Improper EventsN/APASS
    Improper Authorization SchemeN/APASS
    Integer Over/UnderflowN/APASS
    Logical IssuesN/APASS
    Oracle IssuesN/APASS
    Outdated Compiler VersionN/APASS
    Race ConditionsN/APASS
    ReentrancyN/APASS
    Signature IssuesN/APASS
    Unbounded LoopsN/APASS
    Unused CodeN/APASS
    Overall Contract Safety PASS

    PistonToken Contract

    Smart Contract Audit - Inheritance

    Smart Contract Audit - Graph

    
     ($) = payable function
     # = non-constant function
     
     Int = Internal
     Ext = External
     Pub = Public
     
     + [Int] IERC20Upgradeable 
        - [Ext] totalSupply
        - [Ext] balanceOf
        - [Ext] transfer #
        - [Ext] allowance
        - [Ext] approve #
        - [Ext] transferFrom #
    
     + [Int] IERC20MetadataUpgradeable (IERC20Upgradeable)
        - [Ext] name
        - [Ext] symbol
        - [Ext] decimals
    
     +  Initializable 
        - [Prv] _isConstructor
    
     +  ContextUpgradeable (Initializable)
        - [Int] __Context_init #
           - modifiers: onlyInitializing
        - [Int] __Context_init_unchained #
           - modifiers: onlyInitializing
        - [Int] _msgSender
        - [Int] _msgData
    
     + [Lib] AddressUpgradeable 
        - [Int] isContract
        - [Int] sendValue #
        - [Int] functionCall #
        - [Int] functionCall #
        - [Int] functionCallWithValue #
        - [Int] functionCallWithValue #
        - [Int] functionStaticCall
        - [Int] functionStaticCall
        - [Int] verifyCallResult
    
     +  ERC20Upgradeable (Initializable, ContextUpgradeable, IERC20Upgradeable, IERC20MetadataUpgradeable)
        - [Int] __ERC20_init #
           - modifiers: onlyInitializing
        - [Int] __ERC20_init_unchained #
           - modifiers: onlyInitializing
        - [Pub] name
        - [Pub] symbol
        - [Pub] decimals
        - [Pub] totalSupply
        - [Pub] balanceOf
        - [Pub] transfer #
        - [Pub] allowance
        - [Pub] approve #
        - [Pub] transferFrom #
        - [Pub] increaseAllowance #
        - [Pub] decreaseAllowance #
        - [Int] _transfer #
        - [Int] _mint #
        - [Int] _burn #
        - [Int] _approve #
        - [Int] _beforeTokenTransfer #
        - [Int] _afterTokenTransfer #
    
     +  OwnableUpgradeable (Initializable, ContextUpgradeable)
        - [Int] __Ownable_init #
           - modifiers: onlyInitializing
        - [Int] __Ownable_init_unchained #
           - modifiers: onlyInitializing
        - [Pub] owner
        - [Pub] renounceOwnership #
           - modifiers: onlyOwner
        - [Pub] transferOwnership #
           - modifiers: onlyOwner
        - [Int] _transferOwnership #
    
     + [Lib] SafeMathUpgradeable 
        - [Int] tryAdd
        - [Int] trySub
        - [Int] tryMul
        - [Int] tryDiv
        - [Int] tryMod
        - [Int] add
        - [Int] sub
        - [Int] mul
        - [Int] div
        - [Int] mod
        - [Int] sub
        - [Int] div
        - [Int] mod
    
     +  PistonToken (Initializable, ERC20Upgradeable, OwnableUpgradeable)
        - [Pub] initialize #
           - modifiers: initializer
        - [Ext] mint #
        - [Ext]  ($)
        - [Pub] excludeFromFees #
           - modifiers: onlyOwner
        - [Pub] excludeMultipleAccountsFromFees #
           - modifiers: onlyOwner
        - [Ext] setUniswapV2PairAndController #
           - modifiers: onlyOwner
        - [Ext] setFees #
           - modifiers: onlyOwner
        - [Pub] setAutomatedMarketMakerPair #
           - modifiers: onlyOwner
        - [Ext] blacklistAddress #
           - modifiers: onlyOwner
        - [Ext] setTradingEnabled #
           - modifiers: onlyOwner
        - [Prv] _setAutomatedMarketMakerPair #
        - [Ext] setSwapEnabled #
           - modifiers: onlyOwner
        - [Ext] setMaxBuyAmount #
           - modifiers: onlyOwner
        - [Ext] setMaxWalletBalance #
           - modifiers: onlyOwner
        - [Ext] setMaxSellAmount #
           - modifiers: onlyOwner
        - [Ext] setSwapTokensAtAmount #
           - modifiers: onlyOwner
        - [Pub] isExcludedFromFees
        - [Ext] setMintMasterAddress #
        - [Int] _transfer #

    PistonTokenController Contract

    Smart Contract Audit - Inheritance

    Smart Contract Audit - Graph

    
     ($) = payable function
     # = non-constant function
     
     Int = Internal
     Ext = External
     Pub = Public
     
     + [Int] IERC20Upgradeable 
        - [Ext] totalSupply
        - [Ext] balanceOf
        - [Ext] transfer #
        - [Ext] allowance
        - [Ext] approve #
        - [Ext] transferFrom #
    
     + [Int] IERC20MetadataUpgradeable (IERC20Upgradeable)
        - [Ext] name
        - [Ext] symbol
        - [Ext] decimals
    
     +  Initializable 
        - [Prv] _isConstructor
    
     +  ContextUpgradeable (Initializable)
        - [Int] __Context_init #
           - modifiers: onlyInitializing
        - [Int] __Context_init_unchained #
           - modifiers: onlyInitializing
        - [Int] _msgSender
        - [Int] _msgData
    
     + [Lib] AddressUpgradeable 
        - [Int] isContract
        - [Int] sendValue #
        - [Int] functionCall #
        - [Int] functionCall #
        - [Int] functionCallWithValue #
        - [Int] functionCallWithValue #
        - [Int] functionStaticCall
        - [Int] functionStaticCall
        - [Int] verifyCallResult
    
     +  ERC20Upgradeable (Initializable, ContextUpgradeable, IERC20Upgradeable, IERC20MetadataUpgradeable)
        - [Int] __ERC20_init #
           - modifiers: onlyInitializing
        - [Int] __ERC20_init_unchained #
           - modifiers: onlyInitializing
        - [Pub] name
        - [Pub] symbol
        - [Pub] decimals
        - [Pub] totalSupply
        - [Pub] balanceOf
        - [Pub] transfer #
        - [Pub] allowance
        - [Pub] approve #
        - [Pub] transferFrom #
        - [Pub] increaseAllowance #
        - [Pub] decreaseAllowance #
        - [Int] _transfer #
        - [Int] _mint #
        - [Int] _burn #
        - [Int] _approve #
        - [Int] _beforeTokenTransfer #
        - [Int] _afterTokenTransfer #
    
     +  OwnableUpgradeable (Initializable, ContextUpgradeable)
        - [Int] __Ownable_init #
           - modifiers: onlyInitializing
        - [Int] __Ownable_init_unchained #
           - modifiers: onlyInitializing
        - [Pub] owner
        - [Pub] renounceOwnership #
           - modifiers: onlyOwner
        - [Pub] transferOwnership #
           - modifiers: onlyOwner
        - [Int] _transferOwnership #
    
     + [Lib] SafeMathUpgradeable 
        - [Int] tryAdd
        - [Int] trySub
        - [Int] tryMul
        - [Int] tryDiv
        - [Int] tryMod
        - [Int] add
        - [Int] sub
        - [Int] mul
        - [Int] div
        - [Int] mod
        - [Int] sub
        - [Int] div
        - [Int] mod
    
     + [Int] IUniswapV2Pair 
        - [Ext] name
        - [Ext] symbol
        - [Ext] decimals
        - [Ext] totalSupply
        - [Ext] balanceOf
        - [Ext] allowance
        - [Ext] approve #
        - [Ext] transfer #
        - [Ext] transferFrom #
        - [Ext] DOMAIN_SEPARATOR
        - [Ext] PERMIT_TYPEHASH
        - [Ext] nonces
        - [Ext] permit #
        - [Ext] MINIMUM_LIQUIDITY
        - [Ext] factory
        - [Ext] token0
        - [Ext] token1
        - [Ext] getReserves
        - [Ext] price0CumulativeLast
        - [Ext] price1CumulativeLast
        - [Ext] kLast
        - [Ext] mint #
        - [Ext] burn #
        - [Ext] swap #
        - [Ext] skim #
        - [Ext] sync #
        - [Ext] initialize #
    
     + [Int] IUniswapV2Factory 
        - [Ext] feeTo
        - [Ext] feeToSetter
        - [Ext] getPair
        - [Ext] allPairs
        - [Ext] allPairsLength
        - [Ext] createPair #
        - [Ext] setFeeTo #
        - [Ext] setFeeToSetter #
    
     + [Int] IUniswapV2Router01 
        - [Ext] factory
        - [Ext] WETH
        - [Ext] addLiquidity #
        - [Ext] addLiquidityETH ($)
        - [Ext] removeLiquidity #
        - [Ext] removeLiquidityETH #
        - [Ext] removeLiquidityWithPermit #
        - [Ext] removeLiquidityETHWithPermit #
        - [Ext] swapExactTokensForTokens #
        - [Ext] swapTokensForExactTokens #
        - [Ext] swapExactETHForTokens ($)
        - [Ext] swapTokensForExactETH #
        - [Ext] swapExactTokensForETH #
        - [Ext] swapETHForExactTokens ($)
        - [Ext] quote
        - [Ext] getAmountOut
        - [Ext] getAmountIn
        - [Ext] getAmountsOut
        - [Ext] getAmountsIn
    
     + [Int] IUniswapV2Router02 (IUniswapV2Router01)
        - [Ext] removeLiquidityETHSupportingFeeOnTransferTokens #
        - [Ext] removeLiquidityETHWithPermitSupportingFeeOnTransferTokens #
        - [Ext] swapExactTokensForTokensSupportingFeeOnTransferTokens #
        - [Ext] swapExactETHForTokensSupportingFeeOnTransferTokens ($)
        - [Ext] swapExactTokensForETHSupportingFeeOnTransferTokens #
    
     +  PistonTokenController (Initializable, ERC20Upgradeable, OwnableUpgradeable)
        - [Pub] initialize #
           - modifiers: initializer
        - [Ext] setSwapTokensAtAmount #
           - modifiers: onlyOwner
        - [Ext] setContracts #
           - modifiers: onlyOwner
        - [Ext] swapAndLiquify #
           - modifiers: onlyOwner
        - [Prv] swapTokensForBUSD #
        - [Prv] addLiquidity #
        - [Pub] pistonBalance
        - [Pub] getPairBalance
        - [Pub] getTokenAndControllerAddress
    
     + [Int] IToken 
        - [Ext] transferFrom #
        - [Ext] transfer #
        - [Ext] balanceOf
        - [Ext] allowance
        - [Ext] approve #

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    How Do I Interpret the Findings?

    Each of our Findings will be labeled with a Severity level. We always recommend the team resolve High, Medium, and Low severity findings prior to deploying the code to the mainnet. Here is a breakdown on what each Severity level means for the project:

    • High severity indicates that the issue puts a large number of users' funds at risk and has a high probability of exploitation, or the smart contract contains serious logical issues which can prevent the code from operating as intended.
    • Medium severity issues are those which place at least some users' funds at risk and has a medium to high probability of exploitation.
    • Low severity issues have a relatively minor risk association; these issues have a low probability of occurring or may have a minimal impact.
    • Informational issues pose no immediate risk, but inform the project team of opportunities for gas optimizations and following smart contract security best practices.