CapyCoin

Smart Contract Audit Report

Audit Summary

CapyCoin Audit Report CapyCoin is a new BEP-20 token on the Binance Smart Chain.

For this audit, we reviewed the project team's CapyCoin contract at 0x82aDa7c28f3E5A1629B783c827274D669f8C6CB4 and TaxHandler contract at 0xd074BDc326feb3DEbA8F922a845Feb8c0458678C on the Binance Smart Chain Mainnet.

Audit Findings

All findings have been resolved.
Date: February 29th, 2024.
Updated: March 7th, 2024 to reflect the contract's mainnet addresses.
Finding #1 - TaxHandler - Low (Resolved)
Description: The following calculation in the getTaxAmount() function performs a multiplication on the result of a division.
(amount / TAX_POINTS) *
(
    exchangePools[from] == true
        ? _buyTaxPoints
        : _sellTaxPoints
)
Risk/Impact: Division can lead to integer truncation, therefore dividing and subsequently multiplying can cause results to lose precision and become less accurate. Additionally, a fee will not be charged on buys or sells where tokenAmount is less than 1000 Wei.
Recommendation: The above calculation should be modified as follows to perform multiplication before division:
(amount * (exchangePools[from] == true ? _buyTaxPoints : _sellTaxPoints)) / TAX_POINTS
Resolution: The team has implemented the above recommendation.

Finding #2 - CapyCoin - Informational (Resolved)
Description: The pinkAntiBot and taxHandler state variables can only be set one time in the constructor but are not declared immutable.
Recommendation: The above state variables could be declared immutable for additional gas savings on each reference.
Resolution: The team has declared the above state variables immutable.

Contract Overview

CapyCoin Contract:

The total supply of the token is set to 1 billion $CAPYCOIN [1,000,000,000] and is minted to the deployer.

No mint or burn functions are publicly accessible, though the circulating supply can be decreased by sending tokens to the 0x..dead address.

The TaxHandler address and PinkAntiBot address referenced in the contract are set by the team upon deployment.

The contract calls into the PinkAntiBot contract during transfers. This contract was not in scope for this audit so our team is unable to provide an assessment with regard to its security.

A fee amount and Fee Receiver address are retrieved from the TaxHandler contract during transfers. The fee amount is deducted from the transfer amount and allocated to the Fee Receiver address.

The contract complies with the BEP-20 token standard.

TaxHandler Contract:

This contract is used by the CapyCoin contract to return a fee amount and Fee Receiver address and enforce potential restrictions during transfers.

Blacklisted accounts are prohibited from transferring tokens unless the recipient is the Fee Receiver address.

There is a Buy fee and Sell fee charged on transfers where either the sender or recipient is an exchange pool address set by the owner.

Fees are not charged on transfers where either the sender or the recipient has been added to the contract's whitelist.

The owner can set the Buy fee and Sell fee to any percentages up to 5% each at any time.

The owner can enable/disable the Buy fee and Sell fee at any time.

The owner can permanently disable the blacklist at any time.

The owner can update the Fee Receiver address at any time.

The owner can add/remove any addresses from the contract's whitelist at any time.

The owner can add/remove any addresses from the contract's blacklist at any time.

The owner can add/remove any addresses from the contract's exchange pool list at any time.

Audit Results

Vulnerability Category	Notes	Result
Arbitrary Jump/Storage Write	N/A	PASS
Centralization of Control	The owner can add any address to the transfer blacklist in the TaxHandler contract.	WARNING
Compiler Issues	N/A	PASS
Delegate Call to Untrusted Contract	N/A	PASS
Dependence on Predictable Variables	N/A	PASS
Ether/Token Theft	N/A	PASS
Flash Loans	N/A	PASS
Front Running	N/A	PASS
Improper Events	N/A	PASS
Improper Authorization Scheme	N/A	PASS
Integer Over/Underflow	N/A	PASS
Logical Issues	N/A	PASS
Oracle Issues	N/A	PASS
Outdated Compiler Version	N/A	PASS
Race Conditions	N/A	PASS
Reentrancy	N/A	PASS
Signature Issues	N/A	PASS
Sybil Attack	N/A	PASS
Unbounded Loops	N/A	PASS
Unused Code	N/A	PASS
Overall Contract Safety		PASS

CapyCoin Contract

Smart Contract Audit - Inheritance

Smart Contract Audit - Graph


 ($) = payable function
 # = non-constant function
 
 Int = Internal
 Ext = External
 Pub = Public
 
 + [Int] IERC20 
    - [Ext] totalSupply
    - [Ext] balanceOf
    - [Ext] transfer #
    - [Ext] allowance
    - [Ext] approve #
    - [Ext] transferFrom #

 + [Int] IERC20Metadata (IERC20)
    - [Ext] name
    - [Ext] symbol
    - [Ext] decimals

 +  Context 
    - [Int] _msgSender
    - [Int] _msgData
    - [Int] _contextSuffixLength

 + [Int] IERC20Errors 

 + [Int] IERC721Errors 

 + [Int] IERC1155Errors 

 +  ERC20 (Context, IERC20, IERC20Metadata, IERC20Errors)
    - [Pub]  #
    - [Pub] name
    - [Pub] symbol
    - [Pub] decimals
    - [Pub] totalSupply
    - [Pub] balanceOf
    - [Pub] transfer #
    - [Pub] allowance
    - [Pub] approve #
    - [Pub] transferFrom #
    - [Int] _transfer #
    - [Int] _update #
    - [Int] _mint #
    - [Int] _burn #
    - [Int] _approve #
    - [Int] _approve #
    - [Int] _spendAllowance #

 +  Ownable (Context)
    - [Pub]  #
    - [Pub] owner
    - [Int] _checkOwner
    - [Pub] renounceOwnership #
       - modifiers: onlyOwner
    - [Pub] transferOwnership #
       - modifiers: onlyOwner
    - [Int] _transferOwnership #

 + [Int] ITaxHandler 
    - [Ext] getTaxAmount

 + [Int] IPinkAntiBot 
    - [Ext] setTokenOwner #
    - [Ext] onPreTransferCheck #

 +  CapyCoin (ERC20, Ownable)
    - [Pub]  #
       - modifiers: ERC20,Ownable
    - [Int] _update #

TaxHandler Contract

Smart Contract Audit - Inheritance

Smart Contract Audit - Graph


 ($) = payable function
 # = non-constant function
 
 Int = Internal
 Ext = External
 Pub = Public
 
 + [Int] IERC20 
    - [Ext] totalSupply
    - [Ext] balanceOf
    - [Ext] transfer #
    - [Ext] allowance
    - [Ext] approve #
    - [Ext] transferFrom #

 + [Int] IERC20Metadata (IERC20)
    - [Ext] name
    - [Ext] symbol
    - [Ext] decimals

 +  Context 
    - [Int] _msgSender
    - [Int] _msgData
    - [Int] _contextSuffixLength

 + [Int] IERC20Errors 

 + [Int] IERC721Errors 

 + [Int] IERC1155Errors 

 +  ERC20 (Context, IERC20, IERC20Metadata, IERC20Errors)
    - [Pub]  #
    - [Pub] name
    - [Pub] symbol
    - [Pub] decimals
    - [Pub] totalSupply
    - [Pub] balanceOf
    - [Pub] transfer #
    - [Pub] allowance
    - [Pub] approve #
    - [Pub] transferFrom #
    - [Int] _transfer #
    - [Int] _update #
    - [Int] _mint #
    - [Int] _burn #
    - [Int] _approve #
    - [Int] _approve #
    - [Int] _spendAllowance #

 +  Ownable (Context)
    - [Pub]  #
    - [Pub] owner
    - [Int] _checkOwner
    - [Pub] renounceOwnership #
       - modifiers: onlyOwner
    - [Pub] transferOwnership #
       - modifiers: onlyOwner
    - [Int] _transferOwnership #

 + [Int] ITaxHandler 
    - [Ext] getTaxAmount

 +  TaxHandler (ITaxHandler, Ownable)
    - [Pub]  #
       - modifiers: Ownable
    - [Ext] getTaxAmount
    - [Ext] setTaxPoints #
       - modifiers: onlyOwner
    - [Ext] setTaxStatus #
       - modifiers: onlyOwner
    - [Ext] disableBlacklist #
       - modifiers: onlyOwner
    - [Ext] setReciever #
       - modifiers: onlyOwner
    - [Ext] addToWhitelist #
       - modifiers: onlyOwner
    - [Ext] removeFromWhitelist #
       - modifiers: onlyOwner
    - [Ext] addToBlacklist #
       - modifiers: onlyOwner
    - [Ext] removeFromBlacklist #
       - modifiers: onlyOwner
    - [Ext] addToExchangePools #
       - modifiers: onlyOwner
    - [Ext] removeFromExchangePools #
       - modifiers: onlyOwner

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What is a SourceHat Audit?

Typically, a smart contract audit is a comprehensive review process designed to discover logical errors, security vulnerabilities, and optimization opportunities within code. A SourceHat Audit takes this a step further by verifying economic logic to ensure the stability of smart contracts and highlighting privileged functionality to create a report that is easy to understand for developers and community members alike.

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.

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