An EVM symbolic execution tool and vulnerability scanner
Project description
Pakala
"ilo Pakala li pakala e mani sona"
- Pakala is a tool to search for exploitable bugs in Ethereum smart contracts.
- Pakala is a symbolic execution engine for the Ethereum Virtual Machine.
The intended public for the tool are security researchers interested by Ethereum / the EVM.
Installation
pip3 install pakala
It works only with python 3.
Usage
Let's look at 0xeBE6c7a839A660a0F04BdF6816e2eA182F5d542C:
it has a transfer(address _to, uint256 _value) function. It is supposedly protected by a require(call.value - _value) >= 0
but that condition always holds because we are substracting two unsigned integers, so the result is also an unsigned integer.
Let's scan it:
./pakala.py 0xeBE6c7a839A660a0F04BdF6816e2eA182F5d542C --force-balance="1 ether"
The contract balance being 0, we won't be able to have it send us some ethers. So we override the balance to be 1 ETH: then it has some "virtual" money to send us.
The tool with tell you a bug was found, and dump you a path of "states". Each state corresponds to a transaction, with constraints that needs to be respected for that code path to be taken, storage that has been read/written...
Advice: look at calldata[0] in the constraints to see the function signature for each transaction.
See ./pakala.py help for more complete usage information.
How does it works? What does it do?
See the introductory article for more information and a demo.
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