# Slither, the Solidity source analyzer Logo [![Build Status](https://img.shields.io/github/workflow/status/crytic/slither/CI/master)](https://github.com/crytic/slither/actions?query=workflow%3ACI) [![Slack Status](https://empireslacking.herokuapp.com/badge.svg)](https://empireslacking.herokuapp.com) [![PyPI version](https://badge.fury.io/py/slither-analyzer.svg)](https://badge.fury.io/py/slither-analyzer) Slither is a Solidity static analysis framework written in Python 3. 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](#features) - [Bugs and Optimizations Detection](#bugs-and-optimizations-detection) - [Printers](#printers) - [Tools](#tools) - [How to Install](#how-to-install) - [Getting Help](#getting-help) - [Publications](#publications) ## Features * Detects vulnerable Solidity code with low false positives * Identifies where the error condition occurs in the source code * Easily integrates into continuous integration and Truffle 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](https://github.com/trailofbits/slither/wiki/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 ## Bugs and Optimizations Detection Run Slither on a Truffle/Embark/Dapp/Etherlime application: ```bash slither . ``` Run Slither on a single file: ```bash slither tests/uninitialized.sol ``` For additional configuration, see the [usage](https://github.com/trailofbits/slither/wiki/Usage) documentation. Use [solc-select](https://github.com/crytic/solc-select) if your contracts require older versions of solc. ### Detectors Num | Detector | What it Detects | Impact | Confidence --- | --- | --- | --- | --- 1 | `name-reused` | [Contract's name reused](https://github.com/crytic/slither/wiki/Detector-Documentation#name-reused) | High | High 2 | `rtlo` | [Right-To-Left-Override control character is used](https://github.com/crytic/slither/wiki/Detector-Documentation#right-to-left-override-character) | High | High 3 | `shadowing-state` | [State variables shadowing](https://github.com/crytic/slither/wiki/Detector-Documentation#state-variable-shadowing) | High | High 4 | `suicidal` | [Functions allowing anyone to destruct the contract](https://github.com/crytic/slither/wiki/Detector-Documentation#suicidal) | High | High 5 | `uninitialized-state` | [Uninitialized state variables](https://github.com/crytic/slither/wiki/Detector-Documentation#uninitialized-state-variables) | High | High 6 | `uninitialized-storage` | [Uninitialized storage variables](https://github.com/crytic/slither/wiki/Detector-Documentation#uninitialized-storage-variables) | High | High 7 | `unprotected-upgrade` | [Unprotected upgradeable contract](https://github.com/crytic/slither/wiki/Detector-Documentation#unprotected-upgradeable-contract) | High | High 8 | `arbitrary-send` | [Functions that send Ether to arbitrary destinations](https://github.com/crytic/slither/wiki/Detector-Documentation#functions-that-send-ether-to-arbitrary-destinations) | High | Medium 9 | `controlled-delegatecall` | [Controlled delegatecall destination](https://github.com/crytic/slither/wiki/Detector-Documentation#controlled-delegatecall) | High | Medium 10 | `reentrancy-eth` | [Reentrancy vulnerabilities (theft of ethers)](https://github.com/crytic/slither/wiki/Detector-Documentation#reentrancy-vulnerabilities) | High | Medium 11 | `erc20-interface` | [Incorrect ERC20 interfaces](https://github.com/crytic/slither/wiki/Detector-Documentation#incorrect-erc20-interface) | Medium | High 12 | `erc721-interface` | [Incorrect ERC721 interfaces](https://github.com/crytic/slither/wiki/Detector-Documentation#incorrect-erc721-interface) | Medium | High 13 | `incorrect-equality` | [Dangerous strict equalities](https://github.com/crytic/slither/wiki/Detector-Documentation#dangerous-strict-equalities) | Medium | High 14 | `locked-ether` | [Contracts that lock ether](https://github.com/crytic/slither/wiki/Detector-Documentation#contracts-that-lock-ether) | Medium | High 15 | `shadowing-abstract` | [State variables shadowing from abstract contracts](https://github.com/crytic/slither/wiki/Detector-Documentation#state-variable-shadowing-from-abstract-contracts) | Medium | High 16 | `tautology` | [Tautology or contradiction](https://github.com/crytic/slither/wiki/Detector-Documentation#tautology-or-contradiction) | Medium | High 17 | `boolean-cst` | [Misuse of Boolean constant](https://github.com/crytic/slither/wiki/Detector-Documentation#misuse-of-a-boolean-constant) | Medium | Medium 18 | `constant-function-asm` | [Constant functions using assembly code](https://github.com/crytic/slither/wiki/Detector-Documentation#constant-functions-using-assembly-code) | Medium | Medium 19 | `constant-function-state` | [Constant functions changing the state](https://github.com/crytic/slither/wiki/Detector-Documentation#constant-functions-changing-the-state) | Medium | Medium 20 | `divide-before-multiply` | [Imprecise arithmetic operations order](https://github.com/crytic/slither/wiki/Detector-Documentation#divide-before-multiply) | Medium | Medium 21 | `reentrancy-no-eth` | [Reentrancy vulnerabilities (no theft of ethers)](https://github.com/crytic/slither/wiki/Detector-Documentation#reentrancy-vulnerabilities-1) | Medium | Medium 22 | `tx-origin` | [Dangerous usage of `tx.origin`](https://github.com/crytic/slither/wiki/Detector-Documentation#dangerous-usage-of-txorigin) | Medium | Medium 23 | `unchecked-lowlevel` | [Unchecked low-level calls](https://github.com/crytic/slither/wiki/Detector-Documentation#unchecked-low-level-calls) | Medium | Medium 24 | `unchecked-send` | [Unchecked send](https://github.com/crytic/slither/wiki/Detector-Documentation#unchecked-send) | Medium | Medium 25 | `uninitialized-local` | [Uninitialized local variables](https://github.com/crytic/slither/wiki/Detector-Documentation#uninitialized-local-variables) | Medium | Medium 26 | `unused-return` | [Unused return values](https://github.com/crytic/slither/wiki/Detector-Documentation#unused-return) | Medium | Medium 27 | `shadowing-builtin` | [Built-in symbol shadowing](https://github.com/crytic/slither/wiki/Detector-Documentation#builtin-symbol-shadowing) | Low | High 28 | `shadowing-local` | [Local variables shadowing](https://github.com/crytic/slither/wiki/Detector-Documentation#local-variable-shadowing) | Low | High 29 | `void-cst` | [Constructor called not implemented](https://github.com/crytic/slither/wiki/Detector-Documentation#void-constructor) | Low | High 30 | `calls-loop` | [Multiple calls in a loop](https://github.com/crytic/slither/wiki/Detector-Documentation/#calls-inside-a-loop) | Low | Medium 31 | `reentrancy-benign` | [Benign reentrancy vulnerabilities](https://github.com/crytic/slither/wiki/Detector-Documentation#reentrancy-vulnerabilities-2) | Low | Medium 32 | `reentrancy-events` | [Reentrancy vulnerabilities leading to out-of-order Events](https://github.com/crytic/slither/wiki/Detector-Documentation#reentrancy-vulnerabilities-3) | Low | Medium 33 | `timestamp` | [Dangerous usage of `block.timestamp`](https://github.com/crytic/slither/wiki/Detector-Documentation#block-timestamp) | Low | Medium 34 | `assembly` | [Assembly usage](https://github.com/crytic/slither/wiki/Detector-Documentation#assembly-usage) | Informational | High 35 | `boolean-equal` | [Comparison to boolean constant](https://github.com/crytic/slither/wiki/Detector-Documentation#boolean-equality) | Informational | High 36 | `deprecated-standards` | [Deprecated Solidity Standards](https://github.com/crytic/slither/wiki/Detector-Documentation#deprecated-standards) | Informational | High 37 | `erc20-indexed` | [Un-indexed ERC20 event parameters](https://github.com/crytic/slither/wiki/Detector-Documentation#unindexed-erc20-event-parameters) | Informational | High 38 | `low-level-calls` | [Low level calls](https://github.com/crytic/slither/wiki/Detector-Documentation#low-level-calls) | Informational | High 39 | `naming-convention` | [Conformity to Solidity naming conventions](https://github.com/crytic/slither/wiki/Detector-Documentation#conformance-to-solidity-naming-conventions) | Informational | High 40 | `pragma` | [If different pragma directives are used](https://github.com/crytic/slither/wiki/Detector-Documentation#different-pragma-directives-are-used) | Informational | High 41 | `solc-version` | [Incorrect Solidity version](https://github.com/crytic/slither/wiki/Detector-Documentation#incorrect-versions-of-solidity) | Informational | High 42 | `unused-state` | [Unused state variables](https://github.com/crytic/slither/wiki/Detector-Documentation#unused-state-variables) | Informational | High 43 | `reentrancy-unlimited-gas` | [Reentrancy vulnerabilities through send and transfer](https://github.com/crytic/slither/wiki/Detector-Documentation#reentrancy-vulnerabilities-4) | Informational | Medium 44 | `too-many-digits` | [Conformance to numeric notation best practices](https://github.com/crytic/slither/wiki/Detector-Documentation#too-many-digits) | Informational | Medium 45 | `constable-states` | [State variables that could be declared constant](https://github.com/crytic/slither/wiki/Detector-Documentation#state-variables-that-could-be-declared-constant) | Optimization | High 46 | `external-function` | [Public function that could be declared external](https://github.com/crytic/slither/wiki/Detector-Documentation#public-function-that-could-be-declared-external) | Optimization | High See the [Detectors Documentation](https://github.com/crytic/slither/wiki/Detector-Documentation) for more information. By default, all the detectors are run. Check out [Crytic](https://crytic.io/) to get access to additional Slither's detectors and GitHub integration. ## Printers ### Quick Review Printers - `human-summary`: [Print a human-readable summary of the contracts](https://github.com/trailofbits/slither/wiki/Printer-documentation#human-summary) - `inheritance-graph`: [Export the inheritance graph of each contract to a dot file](https://github.com/trailofbits/slither/wiki/Printer-documentation#inheritance-graph) - `contract-summary`: [Print a summary of the contracts](https://github.com/trailofbits/slither/wiki/Printer-documentation#contract-summary) ### In-Depth Review Printers - `call-graph`: [Export the call-graph of the contracts to a dot file](https://github.com/trailofbits/slither/wiki/Printer-documentation#call-graph) - `cfg`: [Export the CFG of each functions](https://github.com/trailofbits/slither/wiki/Printer-documentation#cfg) - `function-summary`: [Print a summary of the functions](https://github.com/trailofbits/slither/wiki/Printer-documentation#function-summary) - `vars-and-auth`: [Print the state variables written and the authorization of the functions](https://github.com/crytic/slither/wiki/Printer-documentation#variables-written-and-authorization) To run a printer, use `--print` and a comma-separated list of printers. See the [Printer documentation](https://github.com/crytic/slither/wiki/Printer-documentation) for the complete lists. ## Tools - `slither-check-upgradeability`: [Review `delegatecall`-based upgradeability](https://github.com/crytic/slither/wiki/Upgradeability-Checks) - `slither-prop`: [Automatic unit test and property generation](https://github.com/crytic/slither/wiki/Property-generation) - `slither-flat`: [Flatten a codebase](https://github.com/crytic/slither/wiki/Contract-Flattening) - `slither-check-erc`: [Check the ERC's conformance](https://github.com/crytic/slither/wiki/ERC-Conformance) - `slither-format`: [Automatic patches generation](https://github.com/crytic/slither/wiki/Slither-format) See the [Tool documentation](https://github.com/crytic/slither/wiki/Tool-Documentation) for additional tools. [Contact us](https://www.trailofbits.com/contact/) to get help on building custom tools. ## How to install Slither requires Python 3.6+ and [solc](https://github.com/ethereum/solidity/), the Solidity compiler. ### Using Pip ```bash pip3 install slither-analyzer ``` ### Using Git ```bash git clone https://github.com/crytic/slither.git && cd slither python3 setup.py install ``` We recommend using an Python virtual environment, as detailed in the [Developer Installation Instructions](https://github.com/trailofbits/slither/wiki/Developer-installation), if you prefer to install Slither via git. ### Using Docker Use the [`eth-security-toolbox`](https://github.com/trailofbits/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. ```bash docker pull trailofbits/eth-security-toolbox ``` To share a directory in the container: ```bash docker run -it -v /home/share:/share trailofbits/eth-security-toolbox ``` ## Getting Help Feel free to stop by our [Slack channel](https://empireslacking.herokuapp.com) (#ethereum) for help using or extending Slither. * The [Printer documentation](https://github.com/trailofbits/slither/wiki/Printer-documentation) describes the information Slither is capable of visualizing for each contract. * The [Detector documentation](https://github.com/trailofbits/slither/wiki/Adding-a-new-detector) describes how to write a new vulnerability analyses. * The [API documentation](https://github.com/trailofbits/slither/wiki/API-examples) describes the methods and objects available for custom analyses. * The [SlithIR documentation](https://github.com/trailofbits/slither/wiki/SlithIR) describes the SlithIR intermediate representation. ## License Slither is licensed and distributed under the AGPLv3 license. [Contact us](mailto:opensource@trailofbits.com) if you're looking for an exception to the terms. ## Publications ### Trail of Bits publication - [Slither: A Static Analysis Framework For Smart Contracts](https://arxiv.org/abs/1908.09878), Josselin Feist, Gustavo Grieco, Alex Groce - WETSEB '19 ### External publications - [ReJection: A AST-Based Reentrancy Vulnerability Detection Method](https://www.researchgate.net/publication/339354823_ReJection_A_AST-Based_Reentrancy_Vulnerability_Detection_Method), Rui Ma, Zefeng Jian, Guangyuan Chen, Ke Ma, Yujia Chen - CTCIS 19 - [MPro: Combining Static and Symbolic Analysis forScalable Testing of Smart Contract](https://arxiv.org/pdf/1911.00570.pdf), William Zhang, Sebastian Banescu, Leodardo Pasos, Steven Stewart, Vijay Ganesh - ISSRE 2019 - [ETHPLOIT: From Fuzzing to Efficient Exploit Generation against Smart Contracts](https://wcventure.github.io/FuzzingPaper/Paper/SANER20_ETHPLOIT.pdf), Qingzhao Zhang, Yizhuo Wang, Juanru Li, Siqi Ma - SANER 20 - [Verification of Ethereum Smart Contracts: A Model Checking Approach](http://www.ijmlc.org/vol10/977-AM0059.pdf), Tam Bang, Hoang H Nguyen, Dung Nguyen, Toan Trieu, Tho Quan - IJMLC 20 - [Smart Contract Repair](https://arxiv.org/pdf/1912.05823.pdf), Xiao Liang Yu, Omar Al-Bataineh, David Lo, Abhik Roychoudhury - TOSEM 20 If you are using Slither on an academic work, consider applying to the [Crytic $10k Research Prize](https://blog.trailofbits.com/2019/11/13/announcing-the-crytic-10k-research-prize/).