Mermaid Finance Token security audit, conducted by the Callisto Network Security Department during August 2021.



Mermaid Finance Token Security Audit Report

Are Your Funds Safe?


Audit Request

We would like to request an audit of our smart contract audit($MMD).

Source code

Disclosure policy

Please notify us privately in case of finding critical mistakes. Otherwise, publish the report publicly.

Standard disclosure policy.



1. In scope

2. Findings

In total, 0 issue were reported including:

  • 0 high severity issue.
  • 0 medium severity issue.
  • 0 low severity issue.

In total, 5 notes were reported, including:

  • 0 note.
  • 5 owner privilege.

2.1 Owner privileges

Severity: Owner privileges.


Contract’s owner has right to:

  1. Exclude/include any account from/in fee, using functions excludeFromFee and includeInFee.
  2. Exclude/include any account from/in rewards, using functions excludeFromReward and includeFromReward.
  3. Change fees percentage without limitation, using functions setBurnFeePercentsetTaxFeePercentsetLiquidityFeePercent.
  4. Change maximal amount per transaction (in percentage of totalSupply), using function setMaxTxPercent.
  5. Enable or disable adding liquidity to pool, using function setSwapAndLiquifyEnabled.

3. Security practice

  •  Open-source contact.
  •  The contract should pass a bug bounty after the completion of the security audit.
  •  Public testing.
  •  Automated anomaly detection systems. – NOT IMPLEMENTED. A simple anomaly detection algorithm is recommended to be implemented to detect behavior that is atypical compared to normal for this contract. For instance, the contract must halt deposits in case a large amount is being withdrawn in a short period of time until the owner or the community of the contract approves further operations.
  •  Multisig owner account.
  •  Standard ERC20-related issues. – NOT IMPLEMENTED. It is known that every contract can potentially receive an unintended ERC20-token deposit without the ability to reject it even if the contract is not intended to receive or hold tokens. As a result, it is recommended to implement a function that will allow extracting any arbitrary number of tokens from the contract.
  •  Crosschain address collisions. ETH, ETC, CLO, etc. It is possible that a transaction can be sent to the address of your contract at another chain (as a result of a user mistake or some software fault). It is recommended that you deploy a “mock contract” that would allow you to withdraw any tokens from that address or prevent any funds deposits. Note that you can reject transactions of native token deposited, but you can not reject the deposits of ERC20 tokens. You can use this source code as a mock contract: extractor contract source code. The address of a new contract deployed using CREATE (0xf0) opcode is assigned following this scheme keccak256(rlp([sender, nonce])). Therefore you need to use the same address that was originally used at the main chain to deploy the mock contract at a transaction with the nonce that matches that on the original chain. Example: If you have deployed your main contract with address 0x010101 at your 2021th transaction then you need to increase your nonce of 0x010101 address to 2020 at the chain where your mock contract will be deployed. Then you can deploy your mock contract with your 2021th transaction, and it will receive the same address as your mainnet contract.

4. Conclusion

The audited smart contract can be deployed. No security issues were found during the audit. The notes about owner privileges were made.

It is recommended to adhere to the security practices described in pt. 4 of this report to ensure the contract’s operability and prevent any issues that are not directly related to the code of this smart contract.


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