CryptoAds Token (CRAD) security audit, conducted by the Callisto Network Security Department in April 2019.


CryptoAds (CRAD) Specificities




Audit Request

CRAD CASH using for CryptoAds project.

Source Code:

Disclosure policy:

Public and



Number of lines:


Token desription:

Symbol      : CRAD
Name        : CRAD CASH
Total supply: 100,000,000
Decimals    : 18 
Standard    : ERC20/ERC223


CryptoAds Token (CRAD) Smart Contract Security Audit Report

Are Your Funds Safe?


1. In scope

2. Findings

In total, 6 issues were reported including:

  • 2 medium severity issues.

  • 3 low severity issues.

  • 1 notes.

2.1. ERC223 & ERC20 Implementation

Severity: medium.


  • Implementing both ERC20 & ERC223 in the same contract like it is done in Crad Cash token does not make sense since the implementation still allow token transfer to contracts that may handle token transfers using transfer(address _to, uint256 _value), when in a normal ERC223 implementation transfer(address _to, uint256 _value) will still call transfer(address _to, uint _value, bytes memory _data) by just adding and empty _data array.

    This implementation does not prevent contracts and dapps or users to transfer tokens to contract since the most used function is transfer(address _to, uint256 _value) and not transfer(address _to, uint256 _value, bytes memory _data). all related issues with ERC20 that ERC223 solves are still applicable.

Code snippet:

2.2. ERC223 Transfer

Severity: medium.


  • When calling transfer(address _to, uint _value, bytes memory _data) function, if _to address is a contract tokenFallback is called before assigning the tokens to the contract balance, which will cause compatibiity issues since the ERC223 standard call tokenFallback after assigning the tokens to the contract address, check here for more details.

Code snippet:

2.3. Transfer Event

Severity: low.


A transfer event should be triggered when initializing owner balance.

Code snippet:

2.4. Fallback Function

Severity: note.


  • Any ether that is sent through the fallback function to the contract is forwarded to the contract owner, developers should explain such logic.

Code snippet:

2.5. Transfer to 0x0 Address

Severity: low.


  • transfer(address _to, uint _value, bytes memory _data) does not prevent from sending tokens to 0x0 address.

Code snippet:


Add a requirements to check if _to address is different then address(0).

2.6. Known vulnerabilities of ERC-20 token

Severity: low.


  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.


Add the following code to the transfer(_to address, ...) function:

require( _to != address(this) );

3. Conclusion

The audited smart contract must not be deployed. Reported issues must be fixed prior to the usage of this contract.

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