A Study on Smart Contract Security Vulnerabilities

Blockchain has enabled individuals to communicate and make transactions without a central authority in a secure manner. It leverages concepts such as decentralization, immutability, and consensus to achieve the same. A blockchain is a chain of blocks linked through hashes. It is a distributed ledger where each node on the network has a copy of the blockchain. The consensus mechanism allows nodes to verify the validity of a block and decide on the next block for the chain. Smart Contracts have become the most emerging blockchain application. It is a small piece of executable code deployed on the blockchain. A contract gets triggered after a particular event/condition has been fulfilled. This trigger is generated either due to an invocation from a transaction or an explicit call. Since these contracts involve crypto transactions, they are susceptible to various kinds of attacks and exposed to a multitude of security vulnerabilities. This research paper focuses on the study of different categories of vulnerabilities in the blockchain such as Denial of Service with Failed Call, Randomness using ‘Block Hash’, Mishandled Exception, Immutable Bugs/mistakes, Transaction Ordering Dependency, etc. The paper then discusses various preventive measures and detection tools for the mentioned vulnerabilities.