Smart Contract Security: Protecting Digital Assets

CertiK
6 min readMar 10, 2023

Smart contracts are automated computer programs that facilitate the execution of agreements between parties without the need for intermediaries. These digital agreements operate on blockchain networks and can be used for a variety of purposes, such as trading assets, handling financial transactions, and enforcing the terms of a legal contract. While smart contracts are in many ways much more secure than a traditional agreement, the digitization of contracts has led to some unique smart contract security considerations.

What is Smart Contract Security?

Security — in the context of smart contracts — refers to the prevention of unauthorized access, modification, or theft of the assets and agreements that smart contracts hold. Smart contracts are designed to automate the execution of contractual terms, including the transfer of digital assets. Smart contracts are immutable, meaning that once they are deployed on the blockchain network, they cannot be modified.

NFTs, DeFi, and all of Web3 rely on smart contracts. With tens of billions of dollars held in various Web3 platforms, smart contract security is of critical importance. More than $3.7 billion of value was stolen from Web3 protocols and users in 2022 in hundreds of separate exploits and incidents. As blockchain technology is still in its early stages of development, there are a number of challenges associated with its implementation. These challenges include scalability, interoperability, and privacy. Security is a critical part of addressing these challenges, as secure systems can help prevent attacks and ensure the integrity and reliability of blockchain networks and the value and data they secure.

Smart contract security risks can arise from several factors, such as code bugs, vulnerabilities in the underlying blockchain network, and flaws in the programming language used to create smart contracts. Once a smart contract is deployed, it becomes immutable, meaning that its code cannot be altered. Therefore, if there are any security vulnerabilities in the smart contract, they can be exploited by attackers to steal digital assets or disrupt the normal functioning of the contract.

One of the most significant smart contract security risks is the potential presence of coding errors. Smart contracts are created using programming languages such as Solidity, which is specifically designed for creating smart contracts running on the Ethereum virtual machine. Solidity is a relatively new programming language, and developers may not be familiar with its syntax and rules. This lack of familiarity can result in coding errors that can be exploited by attackers.

Another smart contract security risk is the possibility of a 51% attack on the underlying blockchain network. In a 51% attack, an attacker gains control of 51% of the computing power of the blockchain network, allowing them to manipulate the network’s transactions and create fake and/or fraudulent transactions. This can result in the theft of digital assets from smart contracts or the modification of the contracts themselves.

Smart Contract Security Measures

To mitigate the risks associated with smart contracts, several security measures can be implemented. These measures include:

  • Code Auditing: Code auditing involves reviewing the smart contract’s code to identify and fix any coding errors or vulnerabilities. Smart contract code auditing leverages the knowledge and experience of blockchain security experts and their skill in controlling automated tools to achieve the highest level of code security.
  • Penetration Testing: Penetration testing involves attempting to exploit the smart contract’s security vulnerabilities to identify weaknesses in the contract’s design. Penetration testing can be done manually or using automated tools such as fuzz testers. Fuzz testers are software tools that can generate random inputs to the smart contract to test for unexpected behavior.
  • Formal Verification: Formal verification involves using mathematical proofs to ensure that the smart contract behaves correctly under all possible scenarios. Formal verification can be used to ensure that the smart contract does not have any logic errors or security vulnerabilities.
  • Multi-Signature Wallets: Multi-signature wallets require more than one person to approve a transaction or contract upgrade before it is executed. This can prevent unauthorized access to digital assets and provide an additional layer of security to smart contracts.

Smart Contract Security Best Practices

In addition to the above security measures, there are several best practices that can be followed to ensure the security of smart contracts:

  • Follow the Principle of Least Privilege: The principle of least privilege states that a smart contract should only have the necessary permissions to execute its intended functions. This means that the contract should not have access to any unnecessary data or functions that could be exploited by attackers. By following this principle, developers can limit the potential damage that can be caused by a security breach.
  • Use Open-Source Libraries: Open-source libraries can be used to reduce the risk of coding errors and security vulnerabilities. These libraries have been reviewed and tested by a large community of developers and are less likely to contain vulnerabilities. However, developers should still review the code of these libraries to ensure that they are safe to use for their project’s specific needs.
  • Use a Timelock: Timelocks can be used to prevent unauthorized access to digital assets. A timelock can be set to delay the execution of a transaction until a specific time or block height. This can prevent attackers from stealing digital assets or disrupting the normal functioning of the contract.
  • Test the Smart Contract on a Testnet: Before deploying a smart contract to the mainnet, developers should test the contract on a testnet. Testnets are blockchain networks that are used for testing purposes and do not contain real digital assets. Testing the contract on a testnet can help developers identify any potential issues before deploying the contract to the mainnet.
  • Use a Bug Bounty Program: Bug bounty programs can be used to incentivize ethical hackers to identify and report security vulnerabilities in a smart contract. By offering rewards for finding vulnerabilities, developers can identify and fix issues before attackers can exploit them.

Why You Need a Smart Contract Security Expert

When it comes to securing your smart contracts, you need a Web3 security expert. Smart contract security differs from non-blockchain security in several ways:

  • Immutable nature: One of the key characteristics of blockchain-based smart contracts is their immutability. Once a smart contract is deployed on the blockchain, it cannot be altered. This means that any bugs or vulnerabilities in the code cannot be fixed, and any funds locked in the contract may be lost forever.
  • Limited programming languages: Smart contracts are typically programmed using a limited set of languages, such as Solidity for Ethereum-based contracts. These languages have specific features and limitations that require developers to take extra care when writing code to ensure that it is secure.
  • Decentralization: Smart contracts are executed on a decentralized network, meaning that there is no central authority overseeing their operation. This can make it difficult to detect and prevent security breaches, as there is no single point of control.
  • Economic incentives: Smart contracts typically involve financial transactions, which can attract malicious actors looking to exploit vulnerabilities in the code. The decentralized nature of blockchain-based systems also means that there is no central authority to reimburse users in the event of a security breach or loss of funds.
  • Smart contract auditing: Auditing smart contracts for security vulnerabilities is a complex and specialized process that requires knowledge of both blockchain technology and traditional software security best practices. As smart contract technology is still relatively new, there are few experts in the field, making auditing services expensive and hard to come by.

Smart contracts are a promising technology that are poised to revolutionize the way we do business. However, as with any technology, there are considerations to take into account about their unique security vulnerabilities. Smart contract security risks can arise from several factors, such as code bugs, vulnerabilities in the underlying blockchain network, and flaws in the programming language used to create smart contracts.

To mitigate the risks associated with smart contracts, several security measures can be implemented, such as code auditing, penetration testing, formal verification, multi-signature wallets, and more. By implementing these security measures, we can protect digital assets and ensure the safe and secure use of smart contracts. At CertiK, it’s our mission to secure the Web3 world, and smart contract security is a fundamental part of that.

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