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Advanced Manual
Smart Contract Audit

September 14, 2022

Audit requested by

Crypto Fan Token

0x7ec4f14cbd409dcabe781451c236f294838652fe

Crypto Fan Token / 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 Crypto Fan Token

7. Contract Snapshot

8. Website Review

9. Certificate of Proof

Crypto Fan Token / Security Audit

Audit Summary

Audit Scope

Project Name

Crypto Fan Token

Blockchain

Binance Smart Chain

Smart Contract Language

Solidity

Contract Address

0x7ec4f14cbd409dcabe781451c236f294838652fe

Audit Method

Static Analysis, Manual Review

Date of Audit

14 September 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.

Crypto Fan Token / Security Audit

Tokenomics

Rank Address Quantity (Token) Percentage
1 0x7210f2c0c34a80711b67745b7e5d22383410dd0e 1,000,000,000 100.0000%

Source Code

Coinsult was comissioned by Crypto Fan Token to perform an audit based on the following code:
https://bscscan.com/address/0x7ec4f14cbd409dcabe781451c236f294838652fe#code

Crypto Fan Token / 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.

Crypto Fan Token / 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

2

2

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.

Crypto Fan Token / Security Audit

Missing events arithmetic

Detect missing events for critical arithmetic parameters.

				
					    function setTaxFeePercent(uint256 taxFeeBps) external onlyOwner {
        _taxFee = taxFeeBps;
        require(
            _taxFee + _liquidityFee + _charityFee <= MAX_FEE,
            "Total fee is over 25%"
        );
    }

    function setLiquidityFeePercent(uint256 liquidityFeeBps)
        external
        onlyOwner
    {
        _liquidityFee = liquidityFeeBps;
        require(
            _taxFee + _liquidityFee + _charityFee <= MAX_FEE,
            "Total fee is over 25%"
        );
    }

    function setCharityFeePercent(uint256 charityFeeBps) external onlyOwner {
        _charityFee = charityFeeBps;
        require(
            _taxFee + _liquidityFee + _charityFee <= MAX_FEE,
            "Total fee is over 25%"
        );
    }
				
			

Recommendation

Emit an event for critical parameter changes.

Exploit scenario

				
					contract C {

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

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

updateOwner() has no event, so it is difficult to track off-chain changes in the buy price.

Crypto Fan Token / Security Audit

Costly operations inside a loop

Costly operations inside a loop might waste gas, so optimizations are justified. 

				
					    function includeInReward(address account) external onlyOwner {
        require(_isExcluded[account], "Account is already excluded");
        for (uint256 i = 0; i < _excluded.length; i++) {
            if (_excluded[i] == account) {
                _excluded[i] = _excluded[_excluded.length - 1];
                _tOwned[account] = 0;
                _isExcluded[account] = false;
                _excluded.pop();
                break;
            }
        }
    }
				
			

Recommendation

Use a local variable to hold the loop computation result.

Exploit scenario

				
					contract CostlyOperationsInLoop{

    function bad() external{
        for (uint i=0; i < loop_count; i++){
            state_variable++;
        }
    }

    function good() external{
      uint local_variable = state_variable;
      for (uint i=0; i < loop_count; i++){
        local_variable++;
      }
      state_variable = local_variable;
    }
}
				
			

Incrementing state_variable in a loop incurs a lot of gas because of expensive SSTOREs, which might lead to an out-of-gas.

Crypto Fan Token / 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

Crypto Fan Token / 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?

Crypto Fan Token / 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?

Crypto Fan Token / 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?

Crypto Fan Token / 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?

Crypto Fan Token / 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?

Crypto Fan Token / Security Audit

Other Owner Privileges Check

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

✅ No other important owner privileges to mention.

Crypto Fan Token / Security Audit

Notes

Notes by Crypto Fan Token

No notes provided by the team.

Notes by Coinsult

✅ No notes provided by Coinsult

Crypto Fan Token / Security Audit

Contract Snapshot

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

				
					contract CryptoFanToken is IERC20, Ownable, BaseToken {
    using SafeMath for uint256;
    using Address for address;

    uint256 public constant VERSION = 2;

    uint256 public constant MAX_FEE = 10**4 / 4;

    mapping(address =&gt; uint256) private _rOwned;
    mapping(address =&gt; uint256) private _tOwned;
    mapping(address =&gt; mapping(address =&gt; uint256)) private _allowances;

    mapping(address =&gt; bool) private _isExcludedFromFee;
    mapping(address =&gt; bool) private _isExcluded;
    address[] private _excluded;

    uint256 private constant MAX = ~uint256(0);
    uint256 private _tTotal;
    uint256 private _rTotal;
    uint256 private _tFeeTotal;

    string private _name;
    string private _symbol;
    uint8 private _decimals;

    uint256 public _taxFee;
    uint256 private _previousTaxFee;

    uint256 public _liquidityFee;
    uint256 private _previousLiquidityFee;

    uint256 public _charityFee;
    uint256 private _previousCharityFee;

    IUniswapV2Router02 public uniswapV2Router;
    address public uniswapV2Pair;
    address public _charityAddress;

    bool inSwapAndLiquify;
    bool public swapAndLiquifyEnabled;

    uint256 private numTokensSellToAddToLiquidity;

    event MinTokensBeforeSwapUpdated(uint256 minTokensBeforeSwap);
    event SwapAndLiquifyAmountUpdated(uint256 amount);
    event SwapAndLiquify(
        uint256 tokensSwapped,
        uint256 ethReceived,
        uint256 tokensIntoLiqudity
    );

    modifier lockTheSwap() {
        inSwapAndLiquify = true;
        _;
        inSwapAndLiquify = false;
    }
				
			

Crypto Fan Token / 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?

Crypto Fan Token / Security Audit

Certificate of Proof

Crypto Fan Token

Audited by Coinsult.net

Date: 14 September 2022

Coinsult

coinsult.net

End of report
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