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Advanced Manual
Smart Contract Audit

August 31, 2022

Audit requested by

BUSD Pay

0x4af1a841f9ac1bc559a12314bf61140f04463b28

BUSD Pay / Security Audit

Table of Contents

1. Audit Summary

1.1 Audit scope

1.2 Tokenomics

1.3 Source Code

2. Disclaimer

3. Global Overview

3.1 Informational issues

3.2 Low-risk issues

3.3 Medium-risk issues

3.4 High-risk issues

4. Vulnerabilities Findings

5. Contract Privileges

5.1 Maximum Fee Limit Check

5.2 Contract Pausability Check

5.3 Max Transaction Amount Check

5.4 Exclude From Fees Check

5.5 Ability to Mint Check

5.6 Ability to Blacklist Check

5.7 Owner Privileges Check

6. Notes

6.1 Notes by Coinsult

6.2 Notes by BUSD Pay

7. Contract Snapshot

8. Website Review

9. Certificate of Proof

BUSD Pay / Security Audit

Audit Summary

Audit Scope

Project Name

BUSD Pay

Blockchain

Binance Smart Chain

Smart Contract Language

Solidity

Contract Address

0x4af1a841f9ac1bc559a12314bf61140f04463b28

Audit Method

Static Analysis, Manual Review

Date of Audit

31 August 2022

This audit report has been prepared by Coinsult’s experts at the request of the client. In this audit, the results of the static analysis and the manual code review will be presented. The purpose of the audit is to see if the functions work as intended, and to identify potential security issues within the smart contract.

The information in this report should be used to understand the risks associated with the smart contract. This report can be used as a guide for the development team on how the contract could possibly be improved by remediating the issues that were identified.

BUSD Pay / Security Audit

Tokenomics

Rank Address Quantity (Token) Percentage
1 0x2c7015a66c8e06b2325f19ada51cf92344cc7a8a 1,000,000,000 100.0000%

Source Code

Coinsult was comissioned by BUSD Pay to perform an audit based on the following code:
https://bscscan.com/address/0x4af1a841f9ac1bc559a12314bf61140f04463b28#code

ContractChecker SAFU

BUSD Pay / Security Audit

Disclaimer

This audit report has been prepared by Coinsult’s experts at the request of the client. In this audit, the results of the static analysis and the manual code review will be presented. The purpose of the audit is to see if the functions work as intended, and to identify potential security issues within the smart contract.

The information in this report should be used to understand the risks associated with the smart contract. This report can be used as a guide for the development team on how the contract could possibly be improved by remediating the issues that were identified.

Coinsult is not responsible if a project turns out to be a scam, rug-pull or honeypot. We only provide a detailed analysis for your own research.

Coinsult is not responsible for any financial losses. Nothing in this contract audit is financial advice, please do your own research.

The information provided in this audit is for informational purposes only and should not be considered investment advice. Coinsult does not endorse, recommend, support or suggest to invest in any project. 

Coinsult can not be held responsible for when a project turns out to be a rug-pull, honeypot or scam.

BUSD Pay / Security Audit

Global Overview

Manual Code Review

In this audit report we will highlight the following issues:

Vulnerability Level

Total

Pending

Acknowledged

Resolved

0

0

0

0

7

7

0

0

0

0

0

0

0

0

0

0

Privilege Overview

Coinsult checked the following privileges:

Contract Privilege

Description

Owner can mint?

Owner can blacklist?

Owner can set fees > 25%?

Owner can exclude from fees?

Owner can pause trading?

Owner can set Max TX amount?

More owner priviliges are listed later in the report.

BUSD Pay / Security Audit

Avoid relying on block.timestamp

block.timestamp can be manipulated by miners.

				
					        secondsUntilAutoClaimAvailable = nextClaimTime > block.timestamp ?
                                                    nextClaimTime.sub(block.timestamp) :
                                                    0;
				
			

Recommendation

Do not use block.timestampnow or blockhash as a source of randomness

Exploit scenario

				
					contract Game {

    uint reward_determining_number;

    function guessing() external{
      reward_determining_number = uint256(block.blockhash(10000)) % 10;
    }
}
				
			

Eve is a miner. Eve calls guessing and re-orders the block containing the transaction. As a result, Eve wins the game.

BUSD Pay / Security Audit

Too many digits

Literals with many digits are difficult to read and review.

				
					    function updateGasForProcessing(uint256 newValue) public onlyOwner {
        require(newValue >= 200000 && newValue <= 500000, "gasForProcessing must be between 200,000 and 500,000");
        require(newValue != gasForProcessing, "Cannot update gasForProcessing to same value");
        emit GasForProcessingUpdated(newValue, gasForProcessing);
        gasForProcessing = newValue;
    }
				
			

Recommendation

Exploit scenario

				
					contract MyContract{
    uint 1_ether = 10000000000000000000; 
}
				
			

While 1_ether looks like 1 ether, it is 10 ether. As a result, it’s likely to be used incorrectly.

BUSD Pay / Security Audit

No zero address validation for some functions

Detect missing zero address validation.

				
					    function changeMarketingWallet(address _marketingWallet) external onlyOwner {
        require(_marketingWallet != marketingWallet, "Marketing wallet is already that address");
        require(!isContract(_marketingWallet), "Marketing wallet cannot be a contract");
        marketingWallet = _marketingWallet;
        emit MarketingWalletChanged(marketingWallet);
    }
				
			

Recommendation

Check that the new address is not zero.

Exploit scenario

				
					contract C {

  modifier onlyAdmin {
    if (msg.sender != owner) throw;
    _;
  }

  function updateOwner(address newOwner) onlyAdmin external {
    owner = newOwner;
  }
}
				
			

Bob calls updateOwner without specifying the newOwner, soBob loses ownership of the contract.

BUSD Pay / Security Audit

Functions that send Ether to arbitrary destinations

Unprotected call to a function sending Ether to an arbitrary address.

				
					    function sendBNB(address payable recipient, uint256 amount) internal {
        require(address(this).balance >= amount, "Address: insufficient balance");

        (bool success, ) = recipient.call{value: amount}("");
        require(success, "Address: unable to send value, recipient may have reverted");
    }
				
			

Recommendation

Ensure that an arbitrary user cannot withdraw unauthorized funds.

Exploit scenario

				
					contract ArbitrarySend{
    address destination;
    function setDestination(){
        destination = msg.sender;
    }

    function withdraw() public{
        destination.transfer(this.balance);
    }
}
				
			

Bob calls setDestination and withdraw. As a result he withdraws the contract’s balance.

BUSD Pay / Security Audit

Unchecked transfer

The return value of an external transfer/transferFrom call is not checked.

				
					    function claimStuckTokens(address token) external onlyOwner {
        require(token != address(this), "Owner cannot claim native tokens");
        if (token == address(0x0)) {
            payable(msg.sender).transfer(address(this).balance);
            return;
        }
        IERC20 ERC20token = IERC20(token);
        uint256 balance = ERC20token.balanceOf(address(this));
        ERC20token.transfer(msg.sender, balance);
    }
				
			

Recommendation

Use SafeERC20, or ensure that the transfer/transferFrom return value is checked.

Exploit scenario

				
					contract Token {
    function transferFrom(address _from, address _to, uint256 _value) public returns (bool success);
}
contract MyBank{  
    mapping(address => uint) balances;
    Token token;
    function deposit(uint amount) public{
        token.transferFrom(msg.sender, address(this), amount);
        balances[msg.sender] += amount;
    }
}
				
			

Several tokens do not revert in case of failure and return false. If one of these tokens is used in MyBankdeposit will not revert if the transfer fails, and an attacker can call deposit for free..

BUSD Pay / Security Audit

Divide before multiply

Solidity integer division might truncate. As a result, performing multiplication before division can sometimes avoid loss of precision.

				
					        	uint256 fees = (amount * _totalFees) / 1000;
            amount = amount - fees;
            
            if (burnTaxShare > 0)
            {
                uint256 burnTaxTokens = (fees * burnTaxShare) / _totalFees;
                fees -= burnTaxTokens;
                super._transfer(from,DEAD,burnTaxTokens);
            }
				
			

Recommendation

Consider ordering multiplication before division.

Exploit scenario

				
					contract A {
	function f(uint n) public {
        coins = (oldSupply / n) * interest;
    }
}
				
			

If n is greater than oldSupplycoins will be zero. For example, with oldSupply = 5; n = 10, interest = 2, coins will be zero. If (oldSupply * interest / n) was used, coins would have been 1. In general, it’s usually a good idea to re-arrange arithmetic to perform multiplication before division, unless the limit of a smaller type makes this dangerous.

BUSD Pay / Security Audit

Boolean equality

Detects the comparison to boolean constants.

				
					        if (maxWalletLimitEnabled) 
        {
            if (_isExcludedFromMaxWalletLimit[from]  == false && 
                _isExcludedFromMaxWalletLimit[to]    == false &&
                to != uniswapV2Pair
            ) {
                uint balance  = balanceOf(to);
                require(
                    balance + amount <= maxWalletAmount, 
                    "MaxWallet: Recipient exceeds the maxWalletAmount"
                );
            }
        }
				
			

Recommendation

Remove the equality to the boolean constant.

Exploit scenario

				
					contract A {
	function f(bool x) public {
		// ...
        if (x == true) { // bad!
           // ...
        }
		// ...
	}
}
				
			

Boolean constants can be used directly and do not need to be compare to true or false.

BUSD Pay / Security Audit

Contract Privileges

Maximum Fee Limit Check

Coinsult tests if the owner of the smart contract can set the transfer, buy or sell fee to 25% or more. It is bad practice to set the fees to 25% or more, because owners can prevent healthy trading or even stop trading when the fees are set too high. 

Type of fee

Description

Transfer fee

Buy fee

Sell fee

Type of fee

Description

Max transfer fee

Max buy fee

Max sell fee

BUSD Pay / Security Audit

Contract Pausability Check

Coinsult tests if the owner of the smart contract has the ability to pause the contract. If this is the case, users can no longer interact with the smart contract; users can no longer trade the token.

Privilege Check

Description

Can owner pause the contract?

BUSD Pay / Security Audit

Max Transaction Amount Check

Coinsult tests if the owner of the smart contract can set the maximum amount of a transaction. If the transaction exceeds this limit, the transaction will revert. Owners could prevent normal transactions to take place if they abuse this function.

Privilege Check

Description

Can owner set max tx amount?

BUSD Pay / Security Audit

Exclude From Fees Check

Coinsult tests if the owner of the smart contract can exclude addresses from paying tax fees. If the owner of the smart contract can exclude from fees, they could set high tax fees and exclude themselves from fees and benefit from 0% trading fees. However, some smart contracts require this function to exclude routers, dex, cex or other contracts / wallets from fees.

Privilege Check

Description

Can owner exclude from fees?

BUSD Pay / Security Audit

Ability To Mint Check

Coinsult tests if the owner of the smart contract can mint new tokens. If the contract contains a mint function, we refer to the token’s total supply as non-fixed, allowing the token owner to “mint” more tokens whenever they want.

A mint function in the smart contract allows minting tokens at a later stage. A method to disable minting can also be added to stop the minting process irreversibly.

Minting tokens is done by sending a transaction that creates new tokens inside of the token smart contract. With the help of the smart contract function, an unlimited number of tokens can be created without spending additional energy or money.

Privilege Check

Description

Can owner mint?

BUSD Pay / Security Audit

Ability To Blacklist Check

Coinsult tests if the owner of the smart contract can blacklist accounts from interacting with the smart contract. Blacklisting methods allow the contract owner to enter wallet addresses which are not allowed to interact with the smart contract. 

This method can be abused by token owners to prevent certain / all holders from trading the token. However, blacklists might be good for tokens that want to rule out certain addresses from interacting with a smart contract.

Privilege Check

Description

Can owner blacklist?

BUSD Pay / Security Audit

Other Owner Privileges Check

Coinsult lists all important contract methods which the owner can interact with.

⚠ Owner can set max wallet amount

 

BUSD Pay / Security Audit

Notes

Notes by BUSD Pay

No notes provided by the team.

Notes by Coinsult

When changing tax fees, multiply the tax fees by 10. So when entering 3%, enter 30 instead of 3. The contract is setup this way.

Max transaction amount sell cannot be lower than current amount

Max wallet percentage cannot be lower than 2%

 

BUSD Pay / Security Audit

Contract Snapshot

This is how the constructor of the contract looked at the time of auditing the smart contract.

				
					contract BUSDPay is ERC20, Ownable {

    uint256 public rewardFeeOnBuy       = 40;
    uint256 public marketingFeeOnBuy    = 40;
    uint256 public liquidityFeeOnBuy    = 10;
    uint256 public burnTaxFeeOnBuy      = 10;

    uint256 public rewardFeeOnSell      = 80;
    uint256 public marketingFeeOnSell   = 50;
    uint256 public liquidityFeeOnSell   = 10;
    uint256 public burnTaxFeeOnSell     = 10;

    uint256 public totalBuyFee          = 100;
    uint256 public totalSellFee         = 150;
    uint256 public walletToWalletFee    = 0;

    address public marketingWallet = 0x3C1619D25837390C55850809fCD9a19875b8Be0B;

    address public operator;

    IUniswapV2Router02 public uniswapV2Router;
    address public  uniswapV2Pair;
    
    address private DEAD = 0x000000000000000000000000000000000000dEaD;


    bool    private swapping;
    uint256 public swapTokensAtAmount;

    mapping (address => bool) private _isExcludedFromFees;

    DividendTracker public dividendTracker;
    address public constant rewardToken = 0xe9e7CEA3DedcA5984780Bafc599bD69ADd087D56;//BUSD
    uint256 public gasForProcessing = 300000;

    event ExcludeFromFees(address indexed account, bool isExcluded);
    event FeesBuyUpdated(uint256 rewardFeeOnBuy,uint256 marketingFeeOnBuy,uint256 liquidityFeeOnBuy,uint256 burnTaxFeeOnBuy);
    event FeesSellUpdated(uint256 rewardFeeOnSell,uint256 marketingFeeOnSell,uint256 liquidityFeeOnSell,uint256 burnTaxFeeOnSell);
    event UpdateWalletToWalletFee(uint256 walletToWalletFee);
    event MarketingWalletChanged(address marketingWallet);
    event OperatorWalletChanged(address operatorWallet);
    event SwapAndLiquify(uint256 tokensSwapped, uint256 bnbReceived, uint256 tokensIntoLiqudity);
    event SendMarketing(uint256 bnbSend);
    event UpdateDividendTracker(address indexed newAddress, address indexed oldAddress);
    event GasForProcessingUpdated(uint256 indexed newValue, uint256 indexed oldValue);
    event SendDividends(uint256 amount);
    event ProcessedDividendTracker(
    	uint256 iterations,
    	uint256 claims,
        uint256 lastProcessedIndex,
    	bool indexed automatic,
    	uint256 gas,
    	address indexed processor
    );

				
			

BUSD Pay / Security Audit

Website Review

Coinsult checks the website completely manually and looks for visual, technical and textual errors. We also look at the security, speed and accessibility of the website. In short, a complete check to see if the website meets the current standard of the web development industry. 

Type of check

Description

Mobile friendly?

Contains jQuery errors?

Is SSL secured?

Contains spelling errors?

BUSD Pay / Security Audit

Certificate of Proof

BUSD Pay

Audited by Coinsult.net

Date: 31 August 2022

Coinsult

coinsult.net

End of report
Smart Contract Audit

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