In this audit report we will highlight the following issues:
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.
Note that we only audited the code available to us on this URL at the time of the audit. If the URL is not from any block explorer (main net), it may be subject to change. Always check the contract address on this audit report and compare it to the token you are doing research for.
Contract not yet deployed
Coinsult’s manual smart contract audit is an extensive methodical examination and analysis of the smart contract’s code that is used to interact with the blockchain. This process is conducted to discover errors, issues and security vulnerabilities in the code in order to suggest improvements and ways to fix them.
Coinsult uses software that checks for common vulnerability issues within smart contracts. We use automated tools that scan the contract for security vulnerabilities such as integer-overflow, integer-underflow, out-of-gas-situations, unchecked transfers, etc.
Coinsult’s manual code review involves a human looking at source code, line by line, to find vulnerabilities. Manual code review helps to clarify the context of coding decisions. Automated tools are faster but they cannot take the developer’s intentions and general business logic into consideration.
Coinsult uses certain vulnerability levels, these indicate how bad a certain issue is. The higher the risk, the more strictly it is recommended to correct the error before using the contract.
Coinsult has four statuses that are used for each risk level. Below we explain them briefly.
The Smart Contract Weakness Classification Registry (SWC Registry) is an implementation of the weakness classification scheme proposed in EIP-1470. It is loosely aligned to the terminologies and structure used in the Common Weakness Enumeration (CWE) while overlaying a wide range of weakness variants that are specific to smart contracts.
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Contract does not use a ReEntrancyGuard
One of the major dangers of calling external contracts is that they can take over the control flow. In the reentrancy attack (a.k.a. recursive call attack), a malicious contract calls back into the calling contract before the first invocation of the function is finished. This may cause the different invocations of the function to interact in undesirable ways.
function claimToken_M() public {
User storage user = users[msg.sender];
updateStakeBUSD_IP(msg.sender);
uint256 tokenAmount = user.sM.unClaimedTokens;
user.sM.unClaimedTokens = 0;
_mint(msg.sender, tokenAmount);
emit TokenOperation(msg.sender, "CLAIM", tokenAmount, 0);
}
function claimToken_T() public {
User storage user = users[msg.sender];
updateStakeToken_IP(msg.sender);
uint256 tokenAmount = user.sT.unClaimedTokens;
user.sT.unClaimedTokens = 0;
_mint(msg.sender, tokenAmount);
emit TokenOperation(msg.sender, "CLAIM", tokenAmount, 0);
}
Recommendation
The best practices to avoid Reentrancy weaknesses are: Make sure all internal state changes are performed before the call is executed. This is known as the Checks-Effects-Interactions pattern, or use a reentrancy lock (ie. OpenZeppelin’s ReentrancyGuard.
Avoid relying on block.timestamp
block.timestamp can be manipulated by miners.
function getContractLaunchTime() public view returns (uint256) {
return minZero(startTime, block.timestamp);
}
Recommendation
Do not use block.timestamp
, now
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.
Too many digits
Literals with many digits are difficult to read and review.
function SET_SELL_LIMIT(uint256 value) external {
require(msg.sender == ADMIN, "Admin use only");
require(value >= 40000);
SELL_LIMIT = value * 1 ether;
}
Recommendation
Use: Ether suffix, Time suffix, or The scientific notation
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.
Functions that send Ether to arbitrary destinations
Unprotected call to a function sending Ether to an arbitrary address.
function stakeBUSD(uint256 _amount) public payable {
require(block.timestamp > startTime);
require(_amount >= MIN_INVEST_AMOUNT); // added min invest amount
token.transferFrom(msg.sender, address(this), _amount); // added
uint256 fee = _amount.mul(FEE).div(PERCENT_DIVIDER); // calculate fees on _amount and not msg.value
token.transfer(DEV_POOL, fee);
User storage user = users[msg.sender];
if (user.sM.totalStaked == 0) {
user.sM.checkpoint = maxVal(now, startTime);
totalUsers++;
} else {
updateStakeBUSD_IP(msg.sender);
}
user.sM.lastStakeTime = now;
user.sM.totalStaked = user.sM.totalStaked.add(_amount);
totalBUSDStaked = totalBUSDStaked.add(_amount);
}
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.
Unchecked transfer
The return value of an external transfer/transferFrom call is not checked.
function stakeToken(uint256 tokenAmount) public {
User storage user = users[msg.sender];
require(now >= startTime, "Stake not available yet");
require(
tokenAmount <= balanceOf(msg.sender),
"Insufficient Token Balance"
);
if (user.sT.totalStaked == 0) {
user.sT.checkpoint = now;
} else {
updateStakeToken_IP(msg.sender);
}
_transfer(msg.sender, address(this), tokenAmount);
user.sT.lastStakeTime = now;
user.sT.totalStaked = user.sT.totalStaked.add(tokenAmount);
totalTokenStaked = totalTokenStaked.add(tokenAmount);
}
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 MyBank
, deposit
will not revert if the transfer fails, and an attacker can call deposit
for free..
Missing events arithmetic
Detect missing events for critical arithmetic parameters.
function SET_MIN_INVEST_AMOUNT(uint256 value) external {
require(msg.sender == ADMIN, "Admin use only");
require(value >= 5);
MIN_INVEST_AMOUNT = value * 1 ether;
}
function SET_SELL_LIMIT(uint256 value) external {
require(msg.sender == ADMIN, "Admin use only");
require(value >= 40000);
SELL_LIMIT = value * 1 ether;
}
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.
Conformance to Solidity naming conventions
Allow _ at the beginning of the mixed_case match for private variables and unused parameters.
function SET_MIN_INVEST_AMOUNT(uint256 value) external {
require(msg.sender == ADMIN, "Admin use only");
require(value >= 5);
MIN_INVEST_AMOUNT = value * 1 ether;
}
function SET_SELL_LIMIT(uint256 value) external {
require(msg.sender == ADMIN, "Admin use only");
require(value >= 40000);
SELL_LIMIT = value * 1 ether;
}
Recommendation
Follow the Solidity naming convention.
Rule exceptions
ERC20
)._
at the beginning of the mixed_case
match for private variables and unused parameters.Code With No Effects
Detect the usage of redundant statements that have no effect.
function getContractBUSDBalance() public view returns (uint256) {
// return address(this).balance;
return token.balanceOf(address(this));
}
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.
Coinsult lists all important contract methods which the owner can interact with.
⚠ Owner can set minimum investment amount
⚠ Owner can set sell limit
– Note from the MIM machine team: The sell limit will always be at least 40,000 ether
This is how the constructor of the contract looked at the time of auditing the smart contract.
contract MIMMachine is Token {
uint256 private startTime = now - 1 days;
address payable private ADMIN;
address payable private DEV_POOL;
uint256 public totalUsers;
uint256 public totalBUSDStaked;
uint256 public totalTokenStaked;
uint256 private constant FEE = 100; // 10% fee
uint256 private constant MANUAL_AIRDROP = 50000 ether; // marketing + giveaways
uint256 private constant PERCENT_DIVIDER = 1000;
uint256 private constant PRICE_DIVIDER = 1 ether;
uint256 private constant TIME_STEP = 1 days;
uint256 private constant TIME_TO_UNSTAKE = 7 days;
// Configurables
uint256 public MIN_INVEST_AMOUNT = 5 ether;
uint256 public SELL_LIMIT = 50000 ether;
uint256 public BUSD_DAILYPROFIT = 20; // 2%
uint256 public TOKEN_DAILYPROFIT = 40; // 4%
mapping(address => User) private users;
mapping(uint256 => uint256) private sold;
struct Stake {
uint256 checkpoint;
uint256 totalStaked;
uint256 lastStakeTime;
uint256 unClaimedTokens;
}
struct User {
Stake sM; // staked BUSD
Stake sT; // staked BMT
}
event TokenOperation(
address indexed account,
string txType,
uint256 tokenAmount,
uint256 trxAmount
);
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.
Pretty basic website, could use some more development.
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.