Top 5 Industry-leading Smart Contract Auditing and Security Tools

Iulian Lesanu

@Iulian

AuditBlockchainSecurity ToolsSmart Contract

Smart contract auditing and security tools help developers detect vulnerabilities in their blockchain-based applications. Many of these services can uncover hidden flaws and provide remedial actions to increase protection against malicious attacks. As a result, Web3 developers and DeFi applications cannot afford to launch their projects without using industry-leading services like:

• Cyfrin Aderyn
• Certora
• Slither
• Echidna
• Halmos
• Hacken

This article looks closer at these smart contract auditing tools and their security-enhancing features widely used by developers everywhere.

A Short Introduction to Smart Contract Testing

Smart contract testing is an essential prerequisite for launching a blockchain-based application. This process helps detect and eliminate code vulnerabilities to improve on-chain security and efficiency. Its goal is to confirm the smart contract will behave as expected by its design and fend off exploits across different scenarios and unexpected events.

Several smart contract testing methods exist, but this article will discuss invariant testing. This method requires defining a set of conditions (invariants) that must always hold, regardless of the contract’s state or input. The testers must identify these crucial conditions, confirming that the smart contract will behave as expected without changing status.

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The process advances through state analysis, which rigorously examines the contract in diverse states and input scenarios. Next, developers can employ fuzz testing (fuzzing) to systematically input random data into tests to break specific assertions. This method streamlines the process significantly and identifies almost undetectable scenarios.

Ultimately, the tester aims to expose the contract’s code to the broadest possible range of scenarios and inputs to discover hidden vulnerabilities. Invariant testing and fuzzing help developers reach this goal, and the security tools below accelerate smart contract testing. Some of them enhance the efficiency of this process through advanced math, as we will see below.

Cyfrin Aderyn

Cyfrin is one of the world’s leading smart contract security firms specializing in security audits, tools, and education. One of its main products is Aderyn – an open-source, Rust-based, static analyzer able to detect and report suspected vulnerabilities in smart contracts written in Solidity. The tool traverses the Abstract Syntax Trees (AST) and identifies potential issues. 

Cyfrin Aderyn includes:

• Hardhat and Foundry support

• Modular detectors

• AST Traversal

• Markdown reports

Aderyn automatically analyses a smart contract’s codebase and quickly finds possible threats in an easy-to-digest format. It also allows developers to build their own detectors, adapting the tool to any codebase. This makes it an increasingly popular tool among developers seeking to make their smart contracts impervious to flaws and attacks.

Users must install Rust on their devices before using Cyfrin Aderyn. From there on, they can easily scour their smart contract codes using Aderyn’s “bird’s eye view” and encounter potential loopholes and vulnerabilities.

Cyfrin launched in 2023 but quickly became one of the most reliable smart contract auditing and security smart contract companies. The company has a stellar track record, having already audited important projects such as Linkpool, Swell Network, Farcaster, Dolomite, and others. Moreover, the Cyfrin team has created some of the most-watched educational videos ever.

Behind Cyfrin is an expert team gathering leading professionals from backgrounds like Chainlink, Alchemy, Aragon, WorldCoin, Microsoft, Google, and other popular fintech companies. Led by Patrick Collins, CEO and popular web3 educator, Alex Roan, the CTO, and ex-Chainlink CCIP, and Hans Friese, top blockchain security auditor.

The company paves the way forward by helping increase the security of decentralized applications, top protocols, and organizations in DeFi.

Certora

Certora is among the pioneers of formal verification in the DeFi landscape. The company’s main product, Certora Prover, is a widely used tool for comprehensive audits and verification reports. Smart contract developers use it extensively, and Certora claims it provides “the highest code coverage available in the industry.”

Certora Prover is free to use and allows users to write their own rules. This trial enables developers to run a formal verification of their smart contracts with a runtime of up to 2,000 min/month. The only downside of using it without paying for the subscription is the limited support you receive.

An advanced subscription for a smart contract audit will put developers in touch with Certora’s security experts. The team will carefully craft rules to verify the code’s properties and determine whether the smart contract behaves as expected. Users will receive these rules to run every time they change their codes, thus reducing verification time and costs.

Certora Prover can detect hard-to-find bugs thanks to its mathematically rigorous method of testing code properties. Another great benefit of using this tool is that developers can integrate it from the early stages of their projects. Since the rules remain the same, they will run the same formal verification regardless of code changes.

Lastly, Certora Prover scours the smart contract bytecode to identify scenarios where code properties could produce bugs. The tool then provides a concrete call trace leading to the bug. This process is different from fuzzing, and it compiles the contract into math to determine every possible contract state and contract path.

Slither

Slither is a convenient tool for static code analysis of smart contracts written in Solidity and Vyper. The tool comes from another security provider, Trail of Bits. It is written in Python 3, and its goal is to perform an in-depth analysis of smart contract code with essential features for enhanced protection, such as:

• Automated vulnerability detection
• Automated optimization detection
• Code Understanding
• Assisted code review

Developers can quickly use Slither’s API to detect smart contract bugs. The tool can use a contract’s official documentation to analyze its feasibility in less than 1 second. Advanced scanning helps encounter code optimizations the user might have missed.

Slither is highly compatible with Ethereum-based environments like Truffle, Embark, and Hardhat, making it popular within the broader community of developers. When analyzing a Solidity smart contract, Slither runs predefined lists of detectors and printers. The detectors include vulnerabilities and optimizations the code presents or could have.

Meanwhile, the printers in the Slither analysis include visual representations of the smart contract, such as functions and interoperability features with other smart contracts. Users can customize the analysis by disabling some of the detectors in the Slither analysis or adding their own detectors. Also, the tool does not automatically run printers. Still, users can ask Slither to do it and thus obtain a clearer image of the contract’s security.

Lastly, Slither can discover the issues in a smart contract that might lead to higher gas fees. Slither does not have the same efficiency and reputation-enhancing results as a security audit. Still, many developers use it to reduce the amount of bugs and vulnerabilities.

Echidna

Echidna is an advanced Ethereum smart contract fuzzer developed by Trail of Bits, an industry-leading security provider. The tool gets its name from a bug-eating mammal and has the same mission in the blockchain-based world, where it hunts for smart contract bugs using its unique “property-based fuzzing.”

Echidna was built in the Haskell programming language and uses cutting-edge, grammar-based fuzzing campaigns based on a contract ABI to falsify user-defined predicates or Solidity assertions. This method attempts to find bugs by employing invariants defined by the user instead of searching for potential crashes like most traditional fuzzers.

Many experienced developers use Echidna primarily for its versatile and comprehensive suite of tools and features. For example, the program uses cryptic compile to test contracts. It targets mainly EVM bytecode contracts and can write custom analyses for highly complex smart contracts. 

Echidna is also extremely flexible. Its design allows for quick and seamless mutations in the event of contract code changes. The tool also integrates source code to identify which lines are covered after the fuzzing campaign. Some of its other features include:

• Automatic test case minimization for quick triage.
• Seamless integration into the development workflow.
• Maximum gas usage reporting of the fuzzing campaign.

On the other hand, Echidna has a few limitations that deter some developers from using it extensively. These include insufficient debug information, minimal support for contracts written in Vyper, and limited library support for testing. Moreover, some developers reported the tool crashing when the contract doesn’t link properly.

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Halmos

The last entry in our list of industry-leading smart contract auditing and security tools is Halmos – a symbolic testing software program for EVM smart contracts. The tool is many developers’ choice for testing smart contracts written in Solidity and Foundry. According to the development team behind Halmos, the tool should expand to support other languages, including Vyper and Huff, in the future.

Halmos became popular in the developers’ community for its flexible, open-source properties. The tool can formally verify smart contracts with the same rules and properties written for unit tests for formal specifications through symbolic testing. As a result, users don’t have to rewrite a new set of properties from the start and only add a few specifications with every test they perform. This process saves plenty of time by avoiding duplicative work. 

The tool is designed to work with other formal verification tools with minimal interference. Testing a smart contract with Halmos will automatically verify it passes for all possible inputs or provide counterexamples.

This process does not mean additional specification writing is not necessary. However, it allows developers to reuse the written tests for subsequent unit testing or fuzzing for formal verification purposes.

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With Halmos, developers can choose from numerous quality assurance options, including unit testing, fuzzing, and formal verification, depending on their projects. Using a fuzzer with this tool can help generate random inputs, enabling Halmos to increase confidence in the program’s correctness across all inputs.