ETH_CryptomillionsV2_report.md

cryptomillions.io V2 Token Audit Report.

1. Summary

This document is a security audit report performed by RideSolo, where cryptomillions.io Token has been reviewed.

Symbol       : CPM-1
Name         : Cryptomillions Series 1
Capped supply: 600,000,000
Decimals     : 8 
Standard     : ERC20

2. In scope

• ERC20_CPM1_Token_v2.sol github commit hash f13d70bae67dc5570a7a95816609a36ada80877b.

3. Findings

3 issues were reported including:

• 3 low severity issues.

3.1. Allowance Decrease

Severity: low

Description

The value to be substructed is decreased using safemath sub function meaning that if the value is higher than the remaining allowance the transaction will throw when it could be set to zero instead. multiple scenario can be imagined for the end user.

Code snippet

https://github.com/cryptomillionsofficial/CREATE_ERC20_CPM1_V2/blob/master/ERC20_CPM1_Token_v2.sol#L120#L123

Recommendation

Check if the allowance is lower than the value to be substracted and set the allowance to zero if the condition is met.

3.2. Extra requirement

Severity: low

Description

The following extra requirement is added to _transfer, require(_to != address(msg.sender)), the requirement might cause a compatibility issue especialy if there is any logic implemented in a contract like a batch payment where the msg.sender address will receive some tokens (please not that no reason comme to mind to add such requirement).

Code snippet

https://github.com/cryptomillionsofficial/CREATE_ERC20_CPM1_V2/blob/master/ERC20_CPM1_Token_v2.sol#L103

3.3. Known vulnerabilities of ERC-20 token

Severity: low

Description

1. It is possible to double withdrawal attack. More details here
2. Lack of transaction handling mechanism issue. WARNING! This is a very common issue and it already caused millions of dollars losses for lots of token users! More details here

4. Conclusion

The audited contract is safe.