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Ethpector

Ethpector extracts useful information from smart contract binaries.

Smart contracts are computer programs that coordinate financial agreements on blockchain systems. Although smart contract platforms are transparent in general smart contracts can be pretty opaque if their source-code is not available.

Ethpector sets out to provide tools to analyze smart contracts with and without access to their source-code. Its main focus is to provide tools and heuristics for the automated analysis and classification of smart contracts.

Currently the tool enables:

  • Fetching byte-code for addresses (via web3 RPC and Etherscan)
  • Fetching source-code for addresses (Etherscan and Sourcify)
  • Recovering interfaces including logs from binaries
  • Resolving function and event signatures (via 4bytes and more)
  • It uses control-flow analysis and symbolic execution (mythril) to extract data like calls, stores, logs, etc. including parameters if possible
  • It creates annotated disassembly
  • It implements a simple contract classification method based on interfaces and bytecode
  • It parses metadata like swarm and ipfs hashes

For a more advanced example of how to use this data look at the examples in the experiments folder.

Install

To install run

> pip install ethpector

or build from source directly by first cloning the repository and then running

> make install

CLI

Example:

> ethpector -a --output=functions 0x34CfAC646f301356fAa8B21e94227e3583Fe3F5F

The above command outputs a JSON data-structure describing all functions found in the ethereum binary including entry points (pcs). Furthermore, it contains information on if a function can only be executed by a particular sender (sender constraint) and if it contains certain instructions like logs, creates, suicides etc. To use the -a parameter a connection to an ethereum node or the Etherscan API is needed.

> ethpector -a --output=summary 0x34CfAC646f301356fAa8B21e94227e3583Fe3F5F

The summary output provides an overview of functions and relevant instructions found in the binary like calls to other contracts, logs emitted positions of self destructs etc.

Full list of CLI options:

usage: ethpector [-h] [--version] [-r rpc] [-e etherscan_token] [-c] [-v] [-vv] [-d] [-a] [-f] [--dont_drop_metadatastring] [--output OUTPUT [OUTPUT ...]] [--output_dir OUTPUT_DIR] contract

ethpector -- getting insights into evm binaries.

positional arguments:
  contract              EVM input bytecode or address if -a is provided
options:
-h, --help show this help message and exit.
--version show program's version number and exit.
-r rpc, --rpc rpc
 Ethereum node RPC url.
-e etherscan_token, --etherscan etherscan_token
 Etherscan access token.
-c, --concolic Symbolic execution engine loads values (storage state, call targets) from a node via RPC.
-v, --verbose set loglevel to INFO.
-vv, --very-verbose
 set loglevel to DEBUG.
-d, --deploy Sets if deployment code is provided. EXPERIMENTAL.
-a, --address Analyse address: data is loaded either via RPC or Etherscan.
-f, --tofile Dump output as files.
--offline Do not use any online resources.
--nodotenv Do not load dotenv file to initialize config values.
--dont_drop_metadatastring
 Includes the metadata string to the bytecode analysis.
--output OUTPUT
 Output that should be produced: summary|disassembly|sourcecode|all|basicblocks|calls|storage|functions|known_interfaces. Note: Multiple OUTPUTS possible.
--output_dir OUTPUT_DIR
 Directory to save the results if -f is specified. Default is ethspector-output/.

Data Sources

For improved analysis results both an etherscan API token as well as a ethereum rpc node (infura, alchemy etc.) is beneficial. They can either be configured via command-line options (--rpc and --etherscan), via environment variables or .env files.

An example .env file could look as follows:

ETHPECTOR_ETHERSCAN_TOKEN=[YOUR ETHERSCAN TOKEN]
ETHPECTOR_RPC=https://mainnet.infura.io/v3/[YOUR INFURA TOKEN]
ETHPECTOR_CHAINID=1
ETHPECTOR_MYTHRIL_EXECUTION_TIMEOUT=100
ETHPECTOR_MYTHRIL_CREATE_TIMEOUT=60
ETHPECTOR_MYTHRIL_MAX_DEPTH=512
ETHPECTOR_MYTHRIL_SOLVER_TIMEOUT=200000

A full list of configurable options can be found in src/ethpector/config/config.py.

Library Usage and Examples

In the experiments folder you can find examples of how to use ethpector as a library which is the best way to use it to its full potential.

The example folder holds some interesting binaries as well as addresses to test on.

Graphical User Interface

Ethpector itself does not offer a graphical user interface to conveniently explore the binary code of a smart contract. The project CtrlEth builds a UI for exactly that on top of the Ethpector analysis library.

Development

it is advised to use a virtual environment (venv) for development. Run the following command to initialize one

> python3 -m venv .venv

and activate it (in bash) using

   > source .venv/bin/activate

For more information refer to (venv_). Run

> make dev

to initialize the dev environment. If you want to install ethpector in development mode run

> make install-dev

Before committing anything to the repository please format, lint and test your code in that order. Fix all linter warnings and make sure all test are passing before a commit.

Use the following commands for that:

> make format
> make lint
> make test

or equivalently run

> make pre-commit

Some slow tests are excluded when running make test. Occasionally, one should run

> make test-all

to run the entire test-suite.

Linting and formatting should be automatically executed on every git commit, using pre-commit.

To create the documentation please run:

> make docs

Creating the docs need python dev dependencies to build see (Stackoverflow)

Credits

We thank all the developers of mythril for their great work. Without which this project would not exist.

We would like to thank the following projects for inspiration.

Similar Projects

The following section contains a couple of similar projects and useful libraries that could serve as an alternative or to amend ethpector when analyzing smart contract binaries.

Funding

This project was created at Universität Innsbruck, Austria, in the course of the KRYPTOMONITOR project.

The security research project KRYPTOMONITOR is funded by the Austrian security research programme KIRAS of the Federal Ministry of Agriculture, Regions and Tourism (BMLRT).