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
• Bugs and Optimizations Detection
• Printers
• Tools
• How to Install
• Getting Help
• 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 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
• 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/Hardhat application:

slither .

Run Slither on a single file:

slither tests/uninitialized.sol

For additional configuration, see the usage documentation.

Use solc-select if your contracts require older versions of solc.

Detectors

Num	Detector	What it Detects	Impact	Confidence

1 | abiencoderv2-array | Storage abiencoderv2 array | High | High 2 | array-by-reference | Modifying storage array by value | High | High 3 | incorrect-shift | The order of parameters in a shift instruction is incorrect. | High | High 4 | multiple-constructors | Multiple constructor schemes | High | High 5 | name-reused | Contract's name reused | High | High 6 | public-mappings-nested | Public mappings with nested variables | High | High 7 | rtlo | Right-To-Left-Override control character is used | High | High 8 | shadowing-state | State variables shadowing | High | High 9 | suicidal | Functions allowing anyone to destruct the contract | High | High 10 | uninitialized-state | Uninitialized state variables | High | High 11 | uninitialized-storage | Uninitialized storage variables | High | High 12 | unprotected-upgrade | Unprotected upgradeable contract | High | High 13 | arbitrary-send | Functions that send Ether to arbitrary destinations | High | Medium 14 | controlled-array-length | Tainted array length assignment | High | Medium 15 | controlled-delegatecall | Controlled delegatecall destination | High | Medium 16 | delegatecall-loop | Payable functions using delegatecall inside a loop | High | Medium 17 | msg-value-loop | msg.value inside a loop | High | Medium 18 | reentrancy-eth | Reentrancy vulnerabilities (theft of ethers) | High | Medium 19 | storage-array | Signed storage integer array compiler bug | High | Medium 20 | unchecked-transfer | Unchecked tokens transfer | High | Medium 21 | weak-prng | Weak PRNG | High | Medium 22 | enum-conversion | Detect dangerous enum conversion | Medium | High 23 | erc20-interface | Incorrect ERC20 interfaces | Medium | High 24 | erc721-interface | Incorrect ERC721 interfaces | Medium | High 25 | incorrect-equality | Dangerous strict equalities | Medium | High 26 | locked-ether | Contracts that lock ether | Medium | High 27 | mapping-deletion | Deletion on mapping containing a structure | Medium | High 28 | shadowing-abstract | State variables shadowing from abstract contracts | Medium | High 29 | tautology | Tautology or contradiction | Medium | High 30 | write-after-write | Unused write | Medium | High 31 | boolean-cst | Misuse of Boolean constant | Medium | Medium 32 | constant-function-asm | Constant functions using assembly code | Medium | Medium 33 | constant-function-state | Constant functions changing the state | Medium | Medium 34 | divide-before-multiply | Imprecise arithmetic operations order | Medium | Medium 35 | reentrancy-no-eth | Reentrancy vulnerabilities (no theft of ethers) | Medium | Medium 36 | reused-constructor | Reused base constructor | Medium | Medium 37 | tx-origin | Dangerous usage of tx.origin | Medium | Medium 38 | unchecked-lowlevel | Unchecked low-level calls | Medium | Medium 39 | unchecked-send | Unchecked send | Medium | Medium 40 | uninitialized-local | Uninitialized local variables | Medium | Medium 41 | unused-return | Unused return values | Medium | Medium 42 | incorrect-modifier | Modifiers that can return the default value | Low | High 43 | shadowing-builtin | Built-in symbol shadowing | Low | High 44 | shadowing-local | Local variables shadowing | Low | High 45 | uninitialized-fptr-cst | Uninitialized function pointer calls in constructors | Low | High 46 | variable-scope | Local variables used prior their declaration | Low | High 47 | void-cst | Constructor called not implemented | Low | High 48 | calls-loop | Multiple calls in a loop | Low | Medium 49 | events-access | Missing Events Access Control | Low | Medium 50 | events-maths | Missing Events Arithmetic | Low | Medium 51 | incorrect-unary | Dangerous unary expressions | Low | Medium 52 | missing-zero-check | Missing Zero Address Validation | Low | Medium 53 | reentrancy-benign | Benign reentrancy vulnerabilities | Low | Medium 54 | reentrancy-events | Reentrancy vulnerabilities leading to out-of-order Events | Low | Medium 55 | timestamp | Dangerous usage of block.timestamp | Low | Medium 56 | assembly | Assembly usage | Informational | High 57 | assert-state-change | Assert state change | Informational | High 58 | boolean-equal | Comparison to boolean constant | Informational | High 59 | deprecated-standards | Deprecated Solidity Standards | Informational | High 60 | erc20-indexed | Un-indexed ERC20 event parameters | Informational | High 61 | function-init-state | Function initializing state variables | Informational | High 62 | low-level-calls | Low level calls | Informational | High 63 | missing-inheritance | Missing inheritance | Informational | High 64 | naming-convention | Conformity to Solidity naming conventions | Informational | High 65 | pragma | If different pragma directives are used | Informational | High 66 | redundant-statements | Redundant statements | Informational | High 67 | solc-version | Incorrect Solidity version | Informational | High 68 | unimplemented-functions | Unimplemented functions | Informational | High 69 | unused-state | Unused state variables | Informational | High 70 | costly-loop | Costly operations in a loop | Informational | Medium 71 | dead-code | Functions that are not used | Informational | Medium 72 | reentrancy-unlimited-gas | Reentrancy vulnerabilities through send and transfer | Informational | Medium 73 | similar-names | Variable names are too similar | Informational | Medium 74 | too-many-digits | Conformance to numeric notation best practices | Informational | Medium 75 | constable-states | State variables that could be declared constant | Optimization | High 76 | external-function | Public function that could be declared external | Optimization | High

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

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

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

See the Tool documentation for additional tools.

Contact us to get help on building custom tools.

How to install

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

Using Pip

pip3 install slither-analyzer

Using Git

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, 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

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.

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

Title	Usage	Authors	Venue
ReJection: A AST-Based Reentrancy Vulnerability Detection Method	AST-based analysis built on top of Slither	Rui Ma, Zefeng Jian, Guangyuan Chen, Ke Ma, Yujia Chen	CTCIS 19
MPro: Combining Static and Symbolic Analysis forScalable Testing of Smart Contract	Leverage data dependency through Slither	William Zhang, Sebastian Banescu, Leodardo Pasos, Steven Stewart, Vijay Ganesh	ISSRE 2019
ETHPLOIT: From Fuzzing to Efficient Exploit Generation against Smart Contracts	Leverage data dependency through Slither	Qingzhao Zhang, Yizhuo Wang, Juanru Li, Siqi Ma	SANER 20
Verification of Ethereum Smart Contracts: A Model Checking Approach	Symbolic execution built on top of Slither’s CFG	Tam Bang, Hoang H Nguyen, Dung Nguyen, Toan Trieu, Tho Quan	IJMLC 20
Smart Contract Repair	Rely on Slither’s vulnerabilities detectors	Xiao Liang Yu, Omar Al-Bataineh, David Lo, Abhik Roychoudhury	TOSEM 20
Demystifying Loops in Smart Contracts	Leverage data dependency through Slither	Ben Mariano, Yanju Chen, Yu Feng, Shuvendu Lahiri, Isil Dillig	ASE 20
Trace-Based Dynamic Gas Estimation of Loops in Smart Contracts	Use Slither’s CFG to detect loops	Chunmiao Li, Shijie Nie, Yang Cao, Yijun Yu, Zhenjiang Hu	IEEE Open J. Comput. Soc. 1 (2020)

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