Slither, the Solidity source 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

• Detects vulnerable Solidity code with low false positives
• Identifies where the error condition occurs in the source code
• Easy integration 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) enables simple, high-precision analyses

Changelog v0.8.3

This release lets users to enhance Slither through code comments (see example below), adds a new tool to read variable storage values on-chain (slither-read-storage), removes false positives in existing detectors, improves Solidity 0.8 support, and fixes several bugs. Slither also now supports Foundry.

Please use our slither-action for CI integration!

Enhancing Slither through code comments

In the following code:

• @custom:security non-reentrant before the variable declaration will indicate to Slither that the external calls from this variable are non-reentrant
• @custom:security write-protection="onlyOwner()" will indicate to Slither that writing to this variable must be done through onlyOwner

  contract ReentrancyAndWrite{
  
      /// @custom:security non-reentrant
      /// @custom:security write-protection="onlyOwner()"
      I external_contract;
  
      modifier onlyOwner(){
          // lets assume there is an access control
          _;
      }   
  
      mapping(address => uint) balances;
  
      function withdraw() public{
          uint balance = balances[msg.sender];
  
          external_contract.external_call();
  
          balances[msg.sender] = 0;
          payable(msg.sender).transfer(balance);
      }
      
      function set_protected() public onlyOwner(){
          external_contract = I(msg.sender);
      }  
  
      function set_not_protected() public{
          external_contract = I(msg.sender);
      }
  }

Added

• Enhanced analyses through code comments (#1089)
• slither-read-storage (#968)
• New printer to identify misuse of whenNotPaused (#1128)
• slither-action in the README (#1053)
• Solidity support
  • user defined types (#1135)
  • top level variables (#1032)
  • string.concat (#1086)
  • .offset/length in yul (#1085)
  • unary operation on constant (#1094)
• Support for ERC4626, 2612 in slither-check-erc (#1111)
• pip-audit in the CI (#1006)
• Template for github issue (#1044, #1083)

Improved

• Remove FPs in detectors:
  • dead-code (#1040)
  • Reentrancy in constructor (#1048)
  • reentrancy-no-eth staticall (#1119)
  • unprotected-upgrade (#1046, #1122)
• Solidity support
  • custom error lookup (#1156)
  • Function lookup for bytes (#1163)
  • ternary operator (#1162)
  • Top-level structure with import (#1068)
  • Top level with custom error (#1131)
• Notification when the config file is missing (#1041, #1054)
• Github super linter improvements (#1023, #1045, #1088, #1157)
• slither-check-erc output (#1016)
• Typo in missing zero validation detector (#1037)
• slither-prop support for builder (#712)
• Improved to the Echidna printer (#878, #1132)
• Improve determinism for detector results (#1049)
• Python type hint (#1055)
• Unit tests for the AST parsing (#1069, #1118, #1101)
• Auto install of solc versions in the CI (#1073)
• Show ignored findings by default for the checklist (#1082)
• Typo in slither-mutate (#1104)
• Move to f-strings (#1107, #1110)
• Multiple minors improvements to slither-flat (#1125)
• Prioritize ignore comment over exclude dependencies (#1120)
• Windows support (#1065, #1137)
• Crytic-compile@0.2.3 – which adds Foundry support

Fixed

• Missing json output for printers #1012
• Infinite loop in the RTLO detector (#1108)
• Infinite recursion in show_ignore_findings (#1092)

Install

Slither requires Python 3.6+ and solc, the Solidity compiler.

Using Pip

$ pip install slither-analyzer

Using Git

Use

Run Slither on a Truffle application:

slither .

Run Slither on a single file:

$ slither tests/uninitialized.sol 
[..]
INFO:Detectors:
Uninitialized.destination (tests/uninitialized.sol#5) is never initialized. It is used in:
	- transfer (tests/uninitialized.sol#7-9)
Reference: https://github.com/trailofbits/slither/wiki/Vulnerabilities-Description#uninitialized-state-variables
[..]

Slither can be run on:

• A .sol file
• A Truffle directory
• A directory containing *.sol files (all the *.sol files will be analyzed)
• A glob (be sure to quote the argument when using a glob)

Configuration

• --solc SOLC: Path to solc (default ‘solc’)
• --solc-args SOLC_ARGS: Add custom solc arguments. SOLC_ARGS can contain multiple arguments
• --disable-solc-warnings: Do not print solc warnings
• --solc-ast: Use the solc AST file as input (solc file.sol --ast-json > file.ast.json)
• --json FILE: Export results as JSON

Detectors

By default, all the detectors are run.

Printers

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

Tutorial

Copyright (C) 2018 trailofbits