What is Smart Contract Audit? How to Audit Smart Contract?

Do you want to know What is Smart Contract? How do audit smart contract? and what it can be used for, this guide is perfect for you!

9th May 2019
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Technically A smart contract is a prewritten code completed within a blockchain network (Ethereum is the most famous one) that allows secure targets to get executed when a specified goal is reached. Very similar to a traditional contract with digital on the top.


What is Smart Contract Audit?


Smart contract audit is the review of code by developers to resolve if the code is secure acting as whether there are any existing vulnerabilities, capabilities for future bugs or any errors in coding that could expose users.


With the complexity of the latest programming platform, it is possible for even a well-experienced developer also to make mistakes when writing code. It becomes critical to verify correctness using unit testing and automatic tooling verification.


The smart contract security audit, which is executed using standards and protocols such as Solidified Verification Standard, is done before the code is hosted on Ethereum platform thus it can increase the security of the entire ecosystem and individual projects and block hacks.


Even-though it won't guarantee that the code is 100% secure, the expert(s) reconsidering the code could find the problems and discuss possible improvements to the code to enhance the security of cryptocurrencies. The expert of developers can highlight critical issues that require to be checked and improved.


Particularly, smart contract audits are conducted by third parties to assure that the code is reviewed as carefully as possible. Depending on the complexity of the smart contract, companies may select to engage the services of a specialist smart contract audit team to conduct the audit.


Known Some of the Attacks:


The below list of known attacks which you should be knowledgeable, and defend against when writing smart contracts.


* Race Conditions

* Reentrancy

* Cross-function Race Conditions

* Transaction-Ordering Dependence (TOD) / Front Running

* Timestamp Dependence

* Integer Overflow and Underflow

* DoS with (Unexpected) revert

* DoS with Block Gas Limit

* Forcibly Sending Ether to a Contract

* Deprecated/historical attacks

* Call Depth Attack (deprecated)


How do Audit Smart Contracts? 


Once check the entire audit will be completed on a deployed smart contract because your audit should be performed on a release candidate (RC), or the final Smart Contract stage before public release, as this is what is closest to the end-user product.


Here we are explaining the important audit steps for the smart contract!


First, you have provided A Legal Disclaimer and also Explain your background like Who You Are and your Audit Process in the contract


After that,


* Conduct attack vulnerability tests

* Detail Vulnerabilities Found and Concerns

* Inspect Contract Complexity

* Inspect Failure Preparation

* Figure out the Code Currency

* Search of Re-used Versus Duplicated Code

* Inspect External Calls 

* Check Initial Balance

* Check security of on-chain data

* Analyze N-party Contracts & More…


So this is the basic steps for smart contract audit process if you want to know more smart contract audit or if you are looking for the high-quality smart contract auditing services for your business then you are search is end here!


Developcoins - Smart Contracts Security Audits Platform


We at Developcoins use different kinds of automated tools, to secure your smart contract and to find whether your smart contract can accomplish your business requirements. Apart from automated tools your smart contract code goes under various testing phases like Manual testing which is done by our expert audit team of developers thereafter smart contract comes under unit testing which is done using truffle, test suite is planned for each and every function in your smart contract to know whether your function is capable of managing overflow & underflow condition, reflected variable in that function should handle their value properly, then Solidity-coverage is used to know how much our test cases are entering your smart contract functions, end of the report after reviewed at various level is delivered to the client along with all the possible suggestions and severity issues raised during audit.


Our Smart Contract Security Audit Process Consist of the following Steps:-


Step -1- Specification terms & conditions gathering:-


This is the most critical stage because the detail is the primary key for a successful smart contract audit. Here we will collect all the specifications from clients to know the planned behavior of the smart contract. In this step, we require a brief of the intended behavior of smart contract from your side and we would also collect specification through condition forms.


Step 2:- Manual Code Review


“Manual Code Review is king in smart contract auditing”


A manual code review will involve the team auditing/checking each line of code in order to analyze it for compilation and re-entrance mistakes as well as security issues. Generally, the primary focus should be paid to verifying security issues as these are the biggest threat to the successful long-term implementation of your smart contract.


Goals of manual code review:-


Double-check that every detail in the specification is executed in a smart contract.

Find out that contract does not have any behavior that is not specified in specifications.

Check that contract does not violate original intended behavior of specifications.


Checked vulnerabilities:


We have scanned smart contracts for commonly known and more specific vulnerabilities. Here are some of the commonly known vulnerabilities that we considered:


* Reentrancy

* Transaction-Ordering Dependence

* Timestamp Dependence

* Gas Limit and Loops

* Gasless send

* DoS with (Unexpected) Throw

* Malicious libraries

* DoS with (Unexpected) revert

* DoS with Block Gas Limit

* ERC20 API violation

* Exception disorder

* Balance equality

* Byte array

* Transfer forwards all gas

* Compiler version not fixed

* Redundant fallback function

* Send instead of transfer

* Style guide violation

* Unchecked external call

* Unchecked math

* Unsafe type inference

* Implicit visibility level

* Address hardcoded

* Using delete for arrays

* Integer overflow/underflow

* Locked money

* Private modifier

* Revert/require functions

* Using var

* Visibility

* Using blockhash

* Using SHA3

* Using suicide

* Using throw

* Using the inline assembly


In a manual code review, more than one auditor will review the code.


* We will implement all security attacks known till date on your contract manually to find out security vulnerabilities

* We will also establish that your smart contract has some mechanism to defend against unknown vulnerabilities.

* We would ensure that smart contract code must respond to bugs and vulnerabilities well.


Step 3:- Unit testing:-


Our goal is writing and running the complete test suite.


* In this step, smart contract functions will be unit tested on various parameters and under different kinds of conditions to assure that all ways of functions are specifying as intended.

* In this step, the intended behavior of the smart contract is documented.

* In this step, we would also ensure that smart contract functions are not consuming unnecessary gas.

* Gas limits of functions will be verified in this stage.


Stage 4: Testing with automated tools


Automatic code analysis has the benefit of saving developers massive amounts of time when checking their smart contract code. Automatic analysis of code also allows for experienced penetration testing which helps find vulnerabilities rapidly.


Most of the developers who create Ethereum smart contracts use Truffle to conduct automatic code testing. By choice, other developers use programs like Populus, a python based framework that allows for quick testing. 


Some of the tools we would use are:-


* Manticore

* Solium

* Smart Check

* Oyente

* Slither


In the end, we would provide you an end-to-end report along with details of audit and steps to cover up with the vulnerabilities if we found any in your smart contracts.


Do you need Smart contract Audit Services for your business? Request here for your contract security audit now!


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