slither/README.md

# Slither, the Solidity source analyzer
<img src="./logo.png" alt="Logo" width="500"/>

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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)

## 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:
```
slither .
```

Run Slither on a single file:
```
$ 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 | `rtlo` | [Right-To-Left-Override control character is used](https://github.com/crytic/slither/wiki/Detector-Documentation#right-to-left-override-character) | High | High
2 | `shadowing-state` | [State variables shadowing](https://github.com/crytic/slither/wiki/Detector-Documentation#state-variable-shadowing) | High | High
3 | `suicidal` | [Functions allowing anyone to destruct the contract](https://github.com/crytic/slither/wiki/Detector-Documentation#suicidal) | High | High
4 | `uninitialized-state` | [Uninitialized state variables](https://github.com/crytic/slither/wiki/Detector-Documentation#uninitialized-state-variables) | High | High
5 | `uninitialized-storage` | [Uninitialized storage variables](https://github.com/crytic/slither/wiki/Detector-Documentation#uninitialized-storage-variables) | High | High
6 | `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
7 | `controlled-delegatecall` | [Controlled delegatecall destination](https://github.com/crytic/slither/wiki/Detector-Documentation#controlled-delegatecall) | High | Medium
8 | `reentrancy-eth` | [Reentrancy vulnerabilities (theft of ethers)](https://github.com/crytic/slither/wiki/Detector-Documentation#reentrancy-vulnerabilities) | High | Medium
9 | `erc20-interface` | [Incorrect ERC20 interfaces](https://github.com/crytic/slither/wiki/Detector-Documentation#incorrect-erc20-interface) | Medium | High
10 | `erc721-interface` | [Incorrect ERC721 interfaces](https://github.com/crytic/slither/wiki/Detector-Documentation#incorrect-erc721-interface) | Medium | High
11 | `incorrect-equality` | [Dangerous strict equalities](https://github.com/crytic/slither/wiki/Detector-Documentation#dangerous-strict-equalities) | Medium | High
12 | `locked-ether` | [Contracts that lock ether](https://github.com/crytic/slither/wiki/Detector-Documentation#contracts-that-lock-ether) | Medium | High
13 | `shadowing-abstract` | [State variables shadowing from abstract contracts](https://github.com/crytic/slither/wiki/Detector-Documentation#state-variable-shadowing-from-abstract-contracts) | Medium | High
14 | `tautology` | [Tautology or contradiction](https://github.com/crytic/slither/wiki/Detector-Documentation#tautology-or-contradiction) | Medium | High
15 | `boolean-cst` | [Misuse of Boolean constant](https://github.com/crytic/slither/wiki/Detector-Documentation#misuse-of-a-boolean-constant) | Medium | Medium
16 | `constant-function-asm` | [Constant functions using assembly code](https://github.com/crytic/slither/wiki/Detector-Documentation#constant-functions-using-assembly-code) | Medium | Medium
17 | `constant-function-state` | [Constant functions changing the state](https://github.com/crytic/slither/wiki/Detector-Documentation#constant-functions-changing-the-state) | Medium | Medium
18 | `divide-before-multiply` | [Imprecise arithmetic operations order](https://github.com/crytic/slither/wiki/Detector-Documentation#divide-before-multiply) | Medium | Medium
19 | `reentrancy-no-eth` | [Reentrancy vulnerabilities (no theft of ethers)](https://github.com/crytic/slither/wiki/Detector-Documentation#reentrancy-vulnerabilities-1) | Medium | Medium
20 | `tx-origin` | [Dangerous usage of `tx.origin`](https://github.com/crytic/slither/wiki/Detector-Documentation#dangerous-usage-of-txorigin) | Medium | Medium
21 | `unchecked-lowlevel` | [Unchecked low-level calls](https://github.com/crytic/slither/wiki/Detector-Documentation#unchecked-low-level-calls) | Medium | Medium
22 | `unchecked-send` | [Unchecked send](https://github.com/crytic/slither/wiki/Detector-Documentation#unchecked-send) | Medium | Medium
23 | `uninitialized-local` | [Uninitialized local variables](https://github.com/crytic/slither/wiki/Detector-Documentation#uninitialized-local-variables) | Medium | Medium
24 | `unused-return` | [Unused return values](https://github.com/crytic/slither/wiki/Detector-Documentation#unused-return) | Medium | Medium
25 | `shadowing-builtin` | [Built-in symbol shadowing](https://github.com/crytic/slither/wiki/Detector-Documentation#builtin-symbol-shadowing) | Low | High
26 | `shadowing-local` | [Local variables shadowing](https://github.com/crytic/slither/wiki/Detector-Documentation#local-variable-shadowing) | Low | High
27 | `void-cst` | [Constructor called not implemented](https://github.com/crytic/slither/wiki/Detector-Documentation#void-constructor) | Low | High
28 | `calls-loop` | [Multiple calls in a loop](https://github.com/crytic/slither/wiki/Detector-Documentation/#calls-inside-a-loop) | Low | Medium
29 | `reentrancy-benign` | [Benign reentrancy vulnerabilities](https://github.com/crytic/slither/wiki/Detector-Documentation#reentrancy-vulnerabilities-2) | Low | Medium
30 | `reentrancy-events` | [Reentrancy vulnerabilities leading to out-of-order Events](https://github.com/crytic/slither/wiki/Detector-Documentation#reentrancy-vulnerabilities-3) | Low | Medium
31 | `timestamp` | [Dangerous usage of `block.timestamp`](https://github.com/crytic/slither/wiki/Detector-Documentation#block-timestamp) | Low | Medium
32 | `assembly` | [Assembly usage](https://github.com/crytic/slither/wiki/Detector-Documentation#assembly-usage) | Informational | High
33 | `boolean-equal` | [Comparison to boolean constant](https://github.com/crytic/slither/wiki/Detector-Documentation#boolean-equality) | Informational | High
34 | `deprecated-standards` | [Deprecated Solidity Standards](https://github.com/crytic/slither/wiki/Detector-Documentation#deprecated-standards) | Informational | High
35 | `erc20-indexed` | [Un-indexed ERC20 event parameters](https://github.com/crytic/slither/wiki/Detector-Documentation#unindexed-erc20-event-parameters) | Informational | High
36 | `low-level-calls` | [Low level calls](https://github.com/crytic/slither/wiki/Detector-Documentation#low-level-calls) | Informational | High
37 | `naming-convention` | [Conformance to Solidity naming conventions](https://github.com/crytic/slither/wiki/Detector-Documentation#conformance-to-solidity-naming-conventions) | Informational | High
38 | `pragma` | [If different pragma directives are used](https://github.com/crytic/slither/wiki/Detector-Documentation#different-pragma-directives-are-used) | Informational | High
39 | `solc-version` | [Incorrect Solidity version](https://github.com/crytic/slither/wiki/Detector-Documentation#incorrect-versions-of-solidity) | Informational | High
40 | `unused-state` | [Unused state variables](https://github.com/crytic/slither/wiki/Detector-Documentation#unused-state-variables) | Informational | High
41 | `reentrancy-unlimited-gas` | [Reentrancy vulnerabilities through send and transfer](https://github.com/crytic/slither/wiki/Detector-Documentation#reentrancy-vulnerabilities-4) | Informational | Medium
42 | `too-many-digits` | [Conformance to numeric notation best practices](https://github.com/crytic/slither/wiki/Detector-Documentation#too-many-digits) | Informational | Medium
43 | `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
44 | `external-function` | [Public function that could be declared as external](https://github.com/crytic/slither/wiki/Detector-Documentation#public-function-that-could-be-declared-as-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-flat`: [Flatten a codebase](https://github.com/crytic/slither/wiki/Contract-Flattening)
- `slither-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

```
$ 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.

```
docker pull trailofbits/eth-security-toolbox
```

To share a directory in the container:

```
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.


## Publication
- [Slither: A Static Analysis Framework For Smart Contracts](https://arxiv.org/abs/1908.09878), Josselin Feist, Gustavo Grieco, Alex Groce - WETSEB '19

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/).