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MrCrambo/zac_audit_report.md Secret

Last active Sep 24, 2020
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Summary

This is the report from a security audit performed on ZAC Finance by MrCrambo.

The audit focused primarily on the security of ZAC Finance smart contract.

In scope

  1. https://github.com/ZAC-FINANCE/ZACFinance/blob/master/Contract/ZACFinanceToken.sol

Findings

In total, 2 issues were reported including:

  • 0 high severity issues.

  • 0 medium severity issues.

  • 0 owner privilegies issues.

  • 2 low severity issues.

Security issues

1. Zero address checking

Severity: low severity

Description

There are no zero address checking in functions transfer and transferFrom and also total supply will be calculated as the difference between all the tokens and zero address balance.

Recommendation

We recommend to add burn function for burning extra tokens and to add zero address checking in functions transfer and transferFrom.

2. Known vulnerabilities of ERC-20 token

Severity: low severity

Description

  • It is possible to double withdrawal attack. More details here

  • 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

Recommendation

Add into a function transfer(address _to, ... ) following code:

require( _to != address(this) );

3. No Approval event in transferFrom function

Severity: recommendation

Description

There is no Approval event emitted after the transferFrom function will be executed. But it would be better to call this event, because allowed transfer amount will be changed.

Conclusion

Smart contract contains only low severity issues and could be deployed on mainnet without any threats to investors.

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