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Advanced Manual
Smart Contract Audit

May 5, 2022

Audit requested by

Sex To Earn

0xe7BD139FC3CD3Ae9F8Cf59f1fC2e966cECceb407

Sex To Earn / 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 Sex To Earn

7. Contract Snapshot

8. Website Review

9. Certificate of Proof

Sex To Earn / Security Audit

Audit Summary

Audit Scope

Project Name

Sex To Earn

Website

Blockchain

Binance Smart Chain

Smart Contract Language

Solidity

Contract Address

0xe7BD139FC3CD3Ae9F8Cf59f1fC2e966cECceb407

Audit Method

Static Analysis, Manual Review

Date of Audit

5 May 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.

Sex To Earn / Security Audit

Tokenomics

Rank Address Quantity (Token) Percentage
1 0x2a59b7147b8e522894b2fb870cebc776b5f715e0 100,000,000 100.0000%

Source Code

Coinsult was comissioned by Sex To Earn to perform an audit based on the following code:
https://bscscan.com/address/0xe7bd139fc3cd3ae9f8cf59f1fc2e966cecceb407#code

Sex To Earn / 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.

Sex To Earn / 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

9

0

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.

Sex To Earn / Security Audit

Contract contains Reentrancy vulnerabilities

Additional information: This combination increases risk of malicious intent. While it may be justified by some complex mechanics (e.g. rebase, reflections, buyback). 

More information: Slither

				
					function _transfer(
        address from,
        address to,
        uint256 amount
    ) internal override {
        require(from != address(0), "ERC20: transfer from the zero address");
        require(to != address(0), "ERC20: transfer to the zero address");

        if (amount == 0) {
            super._transfer(from, to, 0);
            return;
        }

        if (!tradingActive) {
            require(
                _isExcludedFromFees[from] || _isExcludedFromFees[to],
                "Trading is not active."
            );
        }

        if (limitsInEffect) {
            if (
                from != owner() &&
                to != owner() &&
                to != address(0) &&
                to != address(0xdead) &&
                !swapping
            ) {
                // only use to prevent sniper buys in the first blocks.
                if (gasLimitActive && automatedMarketMakerPairs[from]) {
                    require(
                        tx.gasprice <= gasPriceLimit,
                        "Gas price exceeds limit."
                    );
                }

                // at launch if the transfer delay is enabled, ensure the block timestamps for purchasers is set -- during launch.
                if (transferDelayEnabled) {
                    if (
                        to != owner() &&
                        to != address(uniswapV2Router) &&
                        to != address(uniswapV2Pair)
                    ) {
                        require(
                            _holderLastTransferTimestamp[tx.origin] <
                                block.number,
                            "_transfer:: Transfer Delay enabled.  Only one purchase per block allowed."
                        );
                        _holderLastTransferTimestamp[tx.origin] = block.number;
                    }
                }

                //when buy
                if (
                    automatedMarketMakerPairs[from] &&
                    !_isExcludedMaxTransactionAmount[to]
                ) {
                    require(
                        amount <= maxTransactionAmount,
                        "Buy transfer amount exceeds the maxTransactionAmount."
                    );
                    require(
                        amount + balanceOf(to) <= maxWallet,
                        "Max wallet exceeded"
                    );
                }
                //when sell
                else if (
                    automatedMarketMakerPairs[to] &&
                    !_isExcludedMaxTransactionAmount[from]
                ) {
                    require(
                        amount <= maxTransactionAmount,
                        "Sell transfer amount exceeds the maxTransactionAmount."
                    );
                } else {
                    require(
                        amount + balanceOf(to) = swapTokensAtAmount;

        if (
            canSwap &&
            swapEnabled &&
            !swapping &&
            !automatedMarketMakerPairs[from] &&
            !_isExcludedFromFees[from] &&
            !_isExcludedFromFees[to]
        ) {
            swapping = true;

            swapBack();

            swapping = false;
        }

        bool takeFee = !swapping;

        // if any account belongs to _isExcludedFromFee account then remove the fee
        if (_isExcludedFromFees[from] || _isExcludedFromFees[to]) {
            takeFee = false;
        }

        uint256 fees = 0;
        // only take fees on buys/sells, do not take on wallet transfers
        if (takeFee) {
            if (
                tradingActiveBlock == block.number &&
                (automatedMarketMakerPairs[to] ||
                    automatedMarketMakerPairs[from])
            ) {
                fees = amount.mul(99).div(100);
                tokensForLiquidity += (fees * 33) / 99;
                tokensForBuyBack += (fees * 33) / 99;
                tokensForMarketing += (fees * 33) / 99;
            }
            // on sell
            if (automatedMarketMakerPairs[to] && sellTotalFees > 0) {
                fees = amount.mul(sellTotalFees).div(100);
                tokensForLiquidity += (fees * sellLiquidityFee) / sellTotalFees;
                tokensForDev += (fees * sellDevFee) / sellTotalFees;
                tokensForMarketing += (fees * sellMarketingFee) / sellTotalFees;
                tokensForBuyBack += (fees * sellBuyBackFee) / sellTotalFees;
            }
            // on buy
            else if (automatedMarketMakerPairs[from] && buyTotalFees > 0) {
                fees = amount.mul(buyTotalFees).div(100);
                tokensForLiquidity += (fees * buyLiquidityFee) / buyTotalFees;
                tokensForDev += (fees * buyDevFee) / buyTotalFees;
                tokensForMarketing += (fees * buyMarketingFee) / buyTotalFees;
                tokensForBuyBack += (fees * buyBuyBackFee) / buyTotalFees;
            }

            if (fees > 0) {
                super._transfer(from, address(this), fees);
            }

            amount -= fees;
        }

        super._transfer(from, to, amount);
    }
				
			

Recommendation

Apply the check-effects-interactions pattern.

Exploit scenario

				
					    function withdrawBalance(){
        // send userBalance[msg.sender] Ether to msg.sender
        // if mgs.sender is a contract, it will call its fallback function
        if( ! (msg.sender.call.value(userBalance[msg.sender])() ) ){
            throw;
        }
        userBalance[msg.sender] = 0;
    }
				
			
Bob uses the re-entrancy bug to call withdrawBalance two times, and withdraw more than its initial deposit to the contract.

Sex To Earn / Security Audit

Too many digits

Literals with many digits are difficult to read and review.

				
					newAmount >= (totalSupply() * 1) / 100000,
				
			

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.

Sex To Earn / Security Audit

No zero address validation for some functions

Detect missing zero address validation.

				
					function updateDevWallet(address newWallet) external onlyOwner {
        emit devWalletUpdated(newWallet, devWallet);
        devWallet = newWallet;
    }
				
			

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.

Sex To Earn / Security Audit

Functions that send Ether to arbitrary destinations

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

				
					 function swapBack() private {
        uint256 contractBalance = balanceOf(address(this));

        // prevent extremely large dumps.
        if (contractBalance > swapTokensAtAmount * 5) {
            contractBalance = swapTokensAtAmount * 5;
        }

        uint256 totalTokensToSwap = tokensForLiquidity +
            tokensForMarketing +
            tokensForDev +
            tokensForBuyBack;
        bool success;

        if (contractBalance == 0 || totalTokensToSwap == 0) {
            return;
        }

        // Halve the amount of liquidity tokens
        uint256 liquidityTokens = (contractBalance * tokensForLiquidity) /
            totalTokensToSwap /
            2;
        uint256 amountToSwapForETH = contractBalance.sub(liquidityTokens);

        uint256 initialETHBalance = address(this).balance;

        swapTokensForEth(amountToSwapForETH);

        uint256 ethBalance = address(this).balance.sub(initialETHBalance);

        uint256 ethForMarketing = ethBalance.mul(tokensForMarketing).div(
            totalTokensToSwap
        );
        uint256 ethForDev = ethBalance.mul(tokensForDev).div(totalTokensToSwap);
        uint256 ethForBuyBack = ethBalance.mul(tokensForBuyBack).div(
            totalTokensToSwap
        );

        uint256 ethForLiquidity = ethBalance -
            ethForMarketing -
            ethForDev -
            ethForBuyBack;

        tokensForLiquidity = 0;
        tokensForMarketing = 0;
        tokensForDev = 0;
        tokensForBuyBack = 0;

        (success, ) = address(devWallet).call{value: ethForDev}("");
        (success, ) = address(buyBackWallet).call{value: ethForBuyBack}("");
        (success, ) = address(marketingWallet).call{value: address(this).balance}("");

        if (liquidityTokens > 0 && ethForLiquidity > 0) {
            addLiquidity(liquidityTokens, ethForLiquidity);
            emit SwapAndLiquify(
                amountToSwapForETH,
                ethForLiquidity,
                tokensForLiquidity
            );
        }

    }

    fallback() external payable{
        revert ("Don't send BNB to this address. Don't do this mistake again!");
    }

    receive() external payable {
        revert ("Don't send BNB to this address. Don't do this mistake again!");
    }
}
				
			

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.

Sex To Earn / Security Audit

Write after write

Variables that are written but never read and written again.

				
					function swapBack() private {
        uint256 contractBalance = balanceOf(address(this));

        // prevent extremely large dumps.
        if (contractBalance > swapTokensAtAmount * 5) {
            contractBalance = swapTokensAtAmount * 5;
        }

        uint256 totalTokensToSwap = tokensForLiquidity +
            tokensForMarketing +
            tokensForDev +
            tokensForBuyBack;
        bool success;

        if (contractBalance == 0 || totalTokensToSwap == 0) {
            return;
        }

        // Halve the amount of liquidity tokens
        uint256 liquidityTokens = (contractBalance * tokensForLiquidity) /
            totalTokensToSwap /
            2;
        uint256 amountToSwapForETH = contractBalance.sub(liquidityTokens);

        uint256 initialETHBalance = address(this).balance;

        swapTokensForEth(amountToSwapForETH);

        uint256 ethBalance = address(this).balance.sub(initialETHBalance);

        uint256 ethForMarketing = ethBalance.mul(tokensForMarketing).div(
            totalTokensToSwap
        );
        uint256 ethForDev = ethBalance.mul(tokensForDev).div(totalTokensToSwap);
        uint256 ethForBuyBack = ethBalance.mul(tokensForBuyBack).div(
            totalTokensToSwap
        );

        uint256 ethForLiquidity = ethBalance -
            ethForMarketing -
            ethForDev -
            ethForBuyBack;

        tokensForLiquidity = 0;
        tokensForMarketing = 0;
        tokensForDev = 0;
        tokensForBuyBack = 0;

        (success, ) = address(devWallet).call{value: ethForDev}("");
        (success, ) = address(buyBackWallet).call{value: ethForBuyBack}("");
        (success, ) = address(marketingWallet).call{value: address(this).balance}("");

        if (liquidityTokens > 0 && ethForLiquidity > 0) {
            addLiquidity(liquidityTokens, ethForLiquidity);
            emit SwapAndLiquify(
                amountToSwapForETH,
                ethForLiquidity,
                tokensForLiquidity
            );
        }

    }

    fallback() external payable{
        revert ("Don't send BNB to this address. Don't do this mistake again!");
    }

    receive() external payable {
        revert ("Don't send BNB to this address. Don't do this mistake again!");
    }
}
				
			

Recommendation

Fix or remove the writes.

Exploit scenario

				
					```solidity
contract Buggy{
    function my_func() external initializer{
        // ...
        a = b;
        a = c;
        // ..
    }
}
				
			

`a` is first asigned to `b`, and then to `c`. As a result the first write does nothing.

Sex To Earn / Security Audit

Divide before multiply

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

				
					fees = amount.mul(sellTotalFees).div(100);
				
			

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.

Sex To Earn / Security Audit

Missing events arithmetic

Detect missing events for critical arithmetic parameters.

				
					function updateBuyFees(
        uint256 _marketingFee,
        uint256 _liquidityFee,
        uint256 _devFee,
        uint256 _buyBackFee
    ) external onlyOwner {
        buyMarketingFee = _marketingFee;
        buyLiquidityFee = _liquidityFee;
        buyDevFee = _devFee;
        buyBuyBackFee = _buyBackFee;
        buyTotalFees =
            buyMarketingFee +
            buyLiquidityFee +
            buyDevFee +
            buyBuyBackFee;
        require(buyTotalFees <= 20, "Must keep fees at 20% or less");
    }
				
			

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.

Sex To Earn / Security Audit

Redundant Statements

Detect the usage of redundant statements that have no effect.

				
					function _msgData() internal view virtual returns (bytes calldata) {
        this; 
        return msg.data;
    }
				
			

Recommendation

Remove redundant statements if they congest code but offer no value.

Exploit scenario

				
					contract RedundantStatementsContract {

    constructor() public {
        uint; // Elementary Type Name
        bool; // Elementary Type Name
        RedundantStatementsContract; // Identifier
    }

    function test() public returns (uint) {
        uint; // Elementary Type Name
        assert; // Identifier
        test; // Identifier
        return 777;
    }
}
				
			

Each commented line references types/identifiers, but performs no action with them, so no code will be generated for such statements and they can be removed.

Sex To Earn / Security Audit

Costly operations inside a loop

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

				
					function swapBack() private {
        uint256 contractBalance = balanceOf(address(this));

        // prevent extremely large dumps.
        if (contractBalance > swapTokensAtAmount * 5) {
            contractBalance = swapTokensAtAmount * 5;
        }

        uint256 totalTokensToSwap = tokensForLiquidity +
            tokensForMarketing +
            tokensForDev +
            tokensForBuyBack;
        bool success;

        if (contractBalance == 0 || totalTokensToSwap == 0) {
            return;
        }

        // Halve the amount of liquidity tokens
        uint256 liquidityTokens = (contractBalance * tokensForLiquidity) /
            totalTokensToSwap /
            2;
        uint256 amountToSwapForETH = contractBalance.sub(liquidityTokens);

        uint256 initialETHBalance = address(this).balance;

        swapTokensForEth(amountToSwapForETH);

        uint256 ethBalance = address(this).balance.sub(initialETHBalance);

        uint256 ethForMarketing = ethBalance.mul(tokensForMarketing).div(
            totalTokensToSwap
        );
        uint256 ethForDev = ethBalance.mul(tokensForDev).div(totalTokensToSwap);
        uint256 ethForBuyBack = ethBalance.mul(tokensForBuyBack).div(
            totalTokensToSwap
        );

        uint256 ethForLiquidity = ethBalance -
            ethForMarketing -
            ethForDev -
            ethForBuyBack;

        tokensForLiquidity = 0;
        tokensForMarketing = 0;
        tokensForDev = 0;
        tokensForBuyBack = 0;

        (success, ) = address(devWallet).call{value: ethForDev}("");
        (success, ) = address(buyBackWallet).call{value: ethForBuyBack}("");
        (success, ) = address(marketingWallet).call{value: address(this).balance}("");

        if (liquidityTokens > 0 && ethForLiquidity > 0) {
            addLiquidity(liquidityTokens, ethForLiquidity);
            emit SwapAndLiquify(
                amountToSwapForETH,
                ethForLiquidity,
                tokensForLiquidity
            );
        }

    }

    fallback() external payable{
        revert ("Don't send BNB to this address. Don't do this mistake again!");
    }

    receive() external payable {
        revert ("Don't send BNB to this address. Don't do this mistake again!");
    }
}
				
			

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.

Sex To Earn / 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

Sex To Earn / 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?

Sex To Earn / 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?

Sex To Earn / 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?

Sex To Earn / 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?

Sex To Earn / 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?

Sex To Earn / Security Audit

Other Owner Privileges Check

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

⚠ Owner can set max wallet balance

⚠ Owner can set sell fee up to 30%

Sex To Earn / Security Audit

Notes

Notes by Sex To Earn

No notes provided by the team.

Notes by Coinsult

✅ No notes provided by Coinsult

Sex To Earn / Security Audit

Contract Snapshot

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

				
					contract sex2earn is ERC20, Ownable {
    using SafeMath for uint256;

    IUniswapV2Router02 public immutable uniswapV2Router;
    address public immutable uniswapV2Pair;
    address public constant deadAddress = address(0xdead);

    bool private swapping;

    address public marketingWallet;
    address public devWallet;
    address public buyBackWallet;

    uint256 public maxTransactionAmount;
    uint256 public swapTokensAtAmount;
    uint256 public maxWallet;
				
			

Sex To Earn / 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?

Sex To Earn / Security Audit

Certificate of Proof

Sex To Earn

Audited by Coinsult.net

Date: 5 May 2022

Coinsult

coinsult.net

End of report
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