Mythril is a security analysis tool for Ethereum smart contracts. It was [introduced at HITBSecConf 2018](https://github.com/b-mueller/smashing-smart-contracts/blob/master/smashing-smart-contracts-1of1.pdf).
* [Installation and setup](#installation-and-setup)
+ [Calculating function hashes](#calculating-function-hashes)
+ [Function signatures](#function-signatures)
* [Credit](#credit)
Mythril is a security analysis tool for Ethereum smart contracts.
## Installation and setup
@ -39,232 +21,20 @@ Install from Pypi:
$ pip3 install mythril
```
If you plan to analyze Solidity code you'll also need the [native version of solc](http://solidity.readthedocs.io/en/v0.4.21/installing-solidity.html#binary-packages). Solcjs is not supported.
## Security analysis
Run `myth -x` with one of the input options described below to run the analysis. This will run the Python modules in the [/analysis/modules](https://github.com/b-mueller/mythril/tree/master/mythril/analysis/modules) directory.
Mythril detects a range of [security issues](security_checks.md), including integer underflows, owner-overwrite-to-Ether-withdrawal, and others. However, the analysis will not detect business logic issues and is not equivalent to formal verification.
### Analyzing Solidity code
In order to work with Solidity source code files, the [solc command line compiler](http://solidity.readthedocs.io/en/develop/using-the-compiler.html) needs to be installed and in path. You can then provide the source file(s) as positional arguments, e.g.:
```
$ myth -x solidity_examples/ether_send.sol
==== Ether send ====
Type: Warning
Contract: Crowdfunding
Function name: withdrawfunds()
PC address: 816
In the function `withdrawfunds()` a non-zero amount of Ether is sent to msg.sender.
There is a check on storage index 7. This storage slot can be written to by calling the function `crowdfunding()`.
--------------------
In file: solidity_examples/ether_send.sol:18
msg.sender.transfer(this.balance)
```
If an input file contains multiple contract definitions, Mythril analyzes the *last* bytecode output produced by solc. You can override this by specifying the contract name explicitly:
```
$ myth -x OmiseGo.sol:OMGToken
```
#### Specifying Solc versions
You can specify a version of the solidity compiler to be used with `--solv <version number>`. Please be aware that this uses [py-solc](https://github.com/ethereum/py-solc) and will only work on Linux and OS X versions of Mavericks, Yosemite and El Capitan as of the time of this writing. It will check you locally installed compiler, if this is not what is specified, it will download binaries on Linux or try to compile from source on OS X.
#### Output formats
By default, analysis results are printed to the terminal in text format. You can change the output format with the `-o` argument:
```
$ myth -xo json underflow.sol
```
The `json` format is useful for integration into other tools, while `-o markdown` creates a [human-readable report](static/sample_report.md).
#### Analyzing a Truffle project
[Truffle Suite](http://truffleframework.com) is a popular development framework for Ethereum. To analyze the smart contracts in a Truffle project, change in the project root directory and run `truffle compile` followed by `myth --truffle`.
### Analyzing on-chain contracts
When analyzing contracts on the blockchain, Mythril will by default query a local node via RPC. You can also use the built-in [INFURA](https://infura.io) support. Alternatively, you can override the RPC settings with the `--rpc` argument.
| Argument | Description |
| ------------- |:-------------:|
| None | Connect to local Ethereum node |
| `-i` | Connect to INFURA Mainnet via HTTPS |
| `--rpc ganache` | Connect to local Ganache |
| `--rpc infura-[netname]` | Connect to infura-mainnet, rinkeby, kovan or ropsten |
The maximum recursion depth for the symbolic execution engine can be controlled with the `--max-depth` argument. The default value is 12. Lowering this value reduces the analysis time as well as the coverage / number of explored states.
The `-g FILENAME` option generates an [interactive jsViz graph](http://htmlpreview.github.io/?https://github.com/b-mueller/mythril/blob/master/static/mythril.html):
```bash
$ myth -ig ./graph.html -a 0x5c436ff914c458983414019195e0f4ecbef9e6dd --max-depth 8
~~The "bounce" effect, while awesome (and thus enabled by default), sometimes messes up the graph layout.~~ Try adding the `--enable-physics` flag for a very entertaining "bounce" effect that unfortunately completely destroys usability.
## Statespace JSON for Traceview Explorer
The `-j FILENAME` option dumps the statespace to json in the format that is required by the [Symbolic Trace Explorer GUI](https://github.com/ConsenSys/mythril-trace-explorer).
```bash
$ ./myth -ij ./statespace.json -a 0x5c436ff914c458983414019195e0f4ecbef9e6dd --max-depth 8
```
## Blockchain exploration
If you are planning to do batch operations or use the contract search features, running a [go-ethereum](https://github.com/ethereum/go-ethereum) node is recommended. Start your local node as follows:
```bash
$ geth --syncmode fast --rpc
```
Mythril builds its own contract database to enable fast search operations. This enables operations like those described in the [legendary "Mitch Brenner" blog post](https://medium.com/@rtaylor30/how-i-snatched-your-153-037-eth-after-a-bad-tinder-date-d1d84422a50b) in ~~seconds~~ minutes instead of days. Unfortunately, the initial sync process is slow. You don't need to sync the whole blockchain right away though: If you abort the syncing process with `ctrl+c`, it will be auto-resumed the next time you run the `--init-db` command.
```bash
$ myth --init-db
Starting synchronization from latest block: 4323706
Processing block 4323000, 3 individual contracts in database
(...)
```
Note that only contracts with non-zero balance are added to the database.
If you experience syncing errors on Mac OS High Sierra, run the following command before starting the sync:
```
export OBJC_DISABLE_INITIALIZE_FORK_SAFETY=YES
```
### Searching from the command line
The search feature allows you to find contract instances that contain specific function calls and opcode sequences. It supports simple boolean expressions, such as:
```bash
$ myth --search "func#changeMultisig(address)#"
$ myth --search "code#PUSH1 0x50,POP#"
$ myth --search "func#changeMultisig(address)# and code#PUSH1 0x50#"
```
### Reading contract storage
You can read the contents of storage slots from a deployed contract as follows.
```bash
$ myth --storage 0,1 -a "0x76799f77587738bfeef09452df215b63d2cfb08a"
Use the `-d` flag to disassemble code. The disassembler accepts a bytecode string or a contract address as its input.
```bash
$ myth -d -c "0x6060"
0 PUSH1 0x60
```
Specifying an address via `-a ADDRESS` will download the contract code from your node.
```bash
$ myth -d -a "0x2a0c0dbecc7e4d658f48e01e3fa353f44050c208"
0 PUSH1 0x60
2 PUSH1 0x40
4 MSTORE
(...)
1135 - FUNCTION safeAdd(uint256,uint256) -
1136 CALLVALUE
1137 ISZERO
```
### Calculating function hashes
To print the Keccak hash for a given function signature:
```bash
$ myth --hash "setOwner(address)"
0x13af4035
```
### Function signatures
Whenever you disassemble or analyze binary code, Mythril will try to resolve function names using its local signature database. The database must be provided at `~/.mythril/signatures.json`. You can start out with the [default file](signatures.json) as follows:
- [EDCon Toronto 2018 - Mythril: Find bugs and verify security properties in your contracts](https://www.youtube.com/watch?v=NJ9StJThxZY&feature=youtu.be&t=3h3m18s)
## Credit
## Acknowledgements
- JSON RPC library is adapted from [ethjsonrpc](https://github.com/ConsenSys/ethjsonrpc) (it doesn't seem to be maintained anymore, and I needed to make some changes to it).
Bernhard Mueller
7 years ago
committed by
GitHub