Efficient Methods to Avoid Smart Contract Vulnerabilities Using Block Chain

Ethereum smart contracts are programs which will run inside public distributed network called block chain. These smart contracts are used to perform operation over ether i. e transfer, receiving across the blockchain, by public to manage their accounts. These smart contracts are immutable once deployed on blockchain. So, developers need to make sure that smart contracts are bug- free at the time of deployment. As we are developing supply chain management (SCM) for textile industry project, to protect the project from smart contract vulnerabilities. In this paper we have analyzed the Decentralized Autonomous organization i. e DAO attack, which takes the advantage of smart contract vulnerability. Some functions are exposed to access by external contracts. The attacker makes use of vulnerability in smart contract and he can implement code to recursively call the function to transfer the funds in to his own account. And also we analyzed Reentrancy attack, which also used by attacker to recursively call the contract to multiple transfers of funds to his own account. And finally we analyzed Underflow attack, which make use of vulnerability in smart contract while transferring ethers between the users without considering limitations of integers values i. e uint8, uint16 etc.