Slither, the smart contract static analyzer

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Slither is a Solidity & Vyper static analysis framework written in Python3. It runs a suite of vulnerability detectors, prints visual information about contract details, and provides an API to easily write custom analyses. Slither enables developers to find vulnerabilities, enhance their code comprehension, and quickly prototype custom analyses.

• Features
• Usage
• How to install
  • Using Pip
  • Using Git
  • Using Docker
  • Integration
• Detectors
• Printers
  • Quick Review Printers
  • In-Depth Review Printers
• Tools
• API Documentation
• Getting Help
• FAQ
• License
• Publications
  • Trail of Bits publication
  • External publications

Features

• Detects vulnerable Solidity code with low false positives (see the list of trophies)
• Identifies where the error condition occurs in the source code
• Easily integrates into continuous integration and Hardhat/Foundry builds
• Built-in 'printers' quickly report crucial contract information
• Detector API to write custom analyses in Python
• Ability to analyze contracts written with Solidity >= 0.4
• Intermediate representation (SlithIR) enables simple, high-precision analyses
• Correctly parses 99.9% of all public Solidity code
• Average execution time of less than 1 second per contract
• Integrates with Github's code scanning in CI
• Support for Vyper smart contracts

Usage

Run Slither on a Hardhat/Foundry/Dapp/Brownie application:

slither .

This is the preferred option if your project has dependencies as Slither relies on the underlying compilation framework to compile source code.

However, you can run Slither on a single file that does not import dependencies:

slither tests/uninitialized.sol

How to install

Note
Slither requires Python 3.8+. If you're not going to use one of the supported compilation frameworks, you need solc, the Solidity compiler; we recommend using solc-select to conveniently switch between solc versions.

Using Pip

python3 -m pip install slither-analyzer

Using Git

git clone https://github.com/crytic/slither.git && cd slither
python3 -m pip install .

We recommend using a Python virtual environment, as detailed in the Developer Installation Instructions, if you prefer to install Slither via git.

Using Docker

Use the eth-security-toolbox docker image. It includes all of our security tools and every major version of Solidity in a single image. /home/share will be mounted to /share in the container.

docker pull trailofbits/eth-security-toolbox

To share a directory in the container:

docker run -it -v /home/share:/share trailofbits/eth-security-toolbox

Integration

• For GitHub action integration, use slither-action.
• For pre-commit integration, use (replace $GIT_TAG with real tag)

  - repo: https://github.com/crytic/slither
  rev: $GIT_TAG
  hooks:
    - id: slither

• To generate a Markdown report, use slither [target] --checklist.
• To generate a Markdown with GitHub source code highlighting, use slither [target] --checklist --markdown-root https://github.com/ORG/REPO/blob/COMMIT/ (replace ORG, REPO, COMMIT)

Detectors

For more information, see

• The Detector Documentation for details on each detector
• The Detection Selection to run only selected detectors. By default, all the detectors are run.
• The Triage Mode to filter individual results

Printers

Quick Review Printers

• human-summary: Print a human-readable summary of the contracts
• inheritance-graph: Export the inheritance graph of each contract to a dot file
• contract-summary: Print a summary of the contracts
• loc: Count the total number lines of code (LOC), source lines of code (SLOC), and comment lines of code (CLOC) found in source files (SRC), dependencies (DEP), and test files (TEST).

In-Depth Review Printers

• call-graph: Export the call-graph of the contracts to a dot file
• cfg: Export the CFG of each functions
• function-summary: Print a summary of the functions
• vars-and-auth: Print the state variables written and the authorization of the functions
• not-pausable: Print functions that do not use whenNotPaused modifier.

To run a printer, use --print and a comma-separated list of printers.

See the Printer documentation for the complete lists.

Tools

• slither-check-upgradeability: Review delegatecall-based upgradeability
• slither-prop: Automatic unit test and property generation
• slither-flat: Flatten a codebase
• slither-check-erc: Check the ERC's conformance
• slither-format: Automatic patch generation
• slither-read-storage: Read storage values from contracts
• slither-interface: Generate an interface for a contract

See the Tool documentation for additional tools.

Contact us to get help on building custom tools.

API Documentation

Documentation on Slither's internals is available here.

Getting Help

Feel free to stop by our Slack channel (#ethereum) for help using or extending Slither.

• The Printer documentation describes the information Slither is capable of visualizing for each contract.

• The Detector documentation describes how to write a new vulnerability analyses.

• The API documentation describes the methods and objects available for custom analyses.

• The SlithIR documentation describes the SlithIR intermediate representation.

FAQ

How do I exclude mocks or tests?

• View our documentation on path filtering.

How do I fix "unknown file" or compilation issues?

• Because slither requires the solc AST, it must have all dependencies available. If a contract has dependencies, slither contract.sol will fail. Instead, use slither . in the parent directory of contracts/ (you should see contracts/ when you run ls). If you have a node_modules/ folder, it must be in the same directory as contracts/. To verify that this issue is related to slither, run the compilation command for the framework you are using e.g npx hardhat compile. That must work successfully; otherwise, slither's compilation engine, crytic-compile, cannot generate the AST.

License

Slither is licensed and distributed under the AGPLv3 license. Contact us if you're looking for an exception to the terms.

Publications

Trail of Bits publication

• Slither: A Static Analysis Framework For Smart Contracts, Josselin Feist, Gustavo Grieco, Alex Groce - WETSEB '19

External publications

If you are using Slither on an academic work, consider applying to the Crytic $10k Research Prize.