Mythril is an assembler and disassembler for Ethereum VM bytecode
Project description
# Mythril
Mythril is an assembler and disassembler for Ethereum VM bytecode. It was created for low-level testing/fuzzing of EVM implementations.
## Installation
Install from Pypi:
`bash $ pip install mythril `
Or, clone the GitHub repo to install the newest master branch:
`bash $ git clone https://github.com/b-mueller/mythril/ $ cd mythril $ python setup.py install `
## Usage
To disassemble a piece of bytecode, pass it on the command line:
`bash $ mythril -d -c "0x606060405050" PUSH1 0x60 PUSH1 0x40 POP POP `
### Modifying and re-assembling code
Mythril can assemble code from input files that contain one instruction per line. To start from an existing contract, save the disassembly to a text file:
`bash $ mythril -d -c "0x606060405050" -o code.easm `
Edit the instructions in a text editor. For example, we can modify the PUSH instructions from the original example:
` PUSH2 0x4050 PUSH4 0x60708090 POP POP `
Save the file and run Mythril with the -a flag to re-assemble:
` $ mythril -a code.easm 0x61405063607080905050 `
The virtual machine language is described in the [Ethereum Yellowpaper](http://gavwood.com/paper.pdf).
### Tracing EVM execution
You can run a piece of bytecode in the [PyEthereum](https://github.com/ethereum/pyethereum) VM and trace its execution using the -t flag. This will output the instructions executed as well as the state of the stack for every execution step. To run code from the command line, use:
`bash $ ./mythril.py -t -c "0x606060405050" vm stack=[] op=PUSH1 steps=0 pc=b'0' address=b'\x01#Eg\x89\xab\xcd\xef\x01#Eg\x89\xab\xcd\xef\x01#Eg' depth=0 pushvalue=96 gas=b'1000000' storage={'code': '0x', 'nonce': '0', 'balance': '0', 'storage': {}} inst=96 vm stack=[b'96'] op=PUSH1 steps=1 depth=0 pushvalue=64 gas=b'999997' pc=b'2' inst=96 vm stack=[b'96', b'64'] op=POP steps=2 depth=0 gas=b'999994' pc=b'4' inst=80 vm stack=[b'96'] op=POP steps=3 depth=0 gas=b'999992' pc=b'5' inst=80 `
For larger contracts, you might prefer to compile them to a binary file instead:
` $ mythril -a contract.easm -o contract.bin $ mythril --trace -f contract.bin `
### Disassembling a contract from the Ethereum blockchain
You can also load code from an existing contract in the Ethereum blockchain. For this, you need to have a full node running, and the RPC debug interface must be activated. For example, when running geth you can do this as follows:
`bash $ geth --syncmode full --rpc --rpcapi eth,debug `
To load contract code from your node, pass the TxID of the transaction that created the contract:
`bash $ mythril -d --txid 0x23112645da9ae684270de843faaeb44918c79a09e019d3a6cf8b87041020340e -o some_contract.easm `
Note: If you want to get code from the Ethereum mainnet, it is easier to download it from [Etherscan](https://etherscan.io).
## Credit
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).
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