Cyber Apocalypse 2023

Navigating the unknown

Solved by : thewhiteh4t

Unknown.sol contains our contract with a simple condition i.e. if value version is 10 updated is set to True
When we connect with netcat and print flag, value of updated is checked, if value is True the flag is presented
First we need to get the current value of target address :

Target address is required to interact with the contract
I used web3py to interact with the contract using the following script :

from web3 import Web3
from solcx import compile_source

w3 = Web3(Web3.HTTPProvider('http://167.172.50.208:32499'))

print(f'Connected : {w3.is_connected()}')

target = '0xBB5Cd458D2691070a1c9460C2d5882253e36a5c0'

with open('Unknown.sol', 'r') as solfile:
        sol_code = solfile.read()

compiled_sol = compile_source(sol_code, output_values=['abi', 'bin'])
contract_id, contract_interface = compiled_sol.popitem()
abi = contract_interface['abi']

print('Updating Value to 10')
contract_instance = w3.eth.contract(address=target, abi=abi)
contract_instance.functions.updateSensors(10).transact()

Script first checks connection with the rpc endpoint
After that it compiles the contract source code, this is required to get value of abi i.e. Application Binary Interface
Its a sort of definition of the functions and data types present in the contract
abi of unknown.sol :

    [
            {
                    'inputs': [
                            {
                                    'internalType': 'uint256',
                                    'name': 'version',
                                    'type': 'uint256'
                            }
                    ],
                    'name': 'updateSensors', 
                    'outputs': [], 
                    'stateMutability': 'nonpayable', 
                    'type': 'function'
            }, 
            {
                    'inputs': [],
                    'name': 'updated', 
                    'outputs': 
                            [
                                    {
                                            'internalType': 'bool', 
                                            'name': '', 
                                            'type': 'bool'
                                    }
                            ],
                    'stateMutability': 'view',
                    'type': 'function'
            }
    ]

So in this we can see our target function name is updateSensors
Finally script calls transact function on updateSensors with argument 10 which is the value of version required to set updated to True
After running the script and going back to netcat we can print the flag

nigamelastic’s method

A lot of stuff to install web3py https://remix.ethereum.org/#lang=en&optimize=false&runs=200&evmVersion=null&version=soljson-v0.8.18+commit.87f61d96.js

Target details:

Private key     :  0x9ccac2d9cb08e106e616725eb93ae220b74e45f84fcba7144385cbbf50be4287
Address         :  0x2F89F82055E803b470Da977C8260B4B25d0Fc43B
Target contract :  0x91FCa15f2602469894850ACEd90A6Fa523338e5d
Setup contract  :  0x00Ac07B771a835CA9E31A38B2FFFB2F1695dF6Fe

connected to rpc url:

 kali  python3
Python 3.11.2 (main, Feb 12 2023, 00:48:52) [GCC 12.2.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> from web3 import Web3
>>> rpc_url="http://144.126.196.198:31920"
>>> web3 = Web3(Web3.HTTPProvider(rpc_url))
>>> web3.isConnected()

Checking stuff in ur private key:

private_key = '0x9ccac2d9cb08e106e616725eb93ae220b74e45f84fcba7'
account: LocalAccount = Account.from_key(private_key)
print(f"Your hot wallet address is {account.address}")
public_address='0x2F89F82055E803b470Da977C8260B4B25d0Fc43B'
>>> balance = web3.eth.get_balance(public_address)
>>> print(balance)
5000000000000000000000
web3.default_account = account.address
target_contract='0x91FCa15f2602469894850ACEd90A6Fa523338e5d'
from web3.gas_strategies.rpc import rpc_gas_price_strategy
web3.eth.set_gas_price_strategy(rpc_gas_price_strategy)

running transaction keeps giving me error

Traceback (most recent call last):
  File "/home/kali/Desktop/repos/Writeups/cyberapocalypse/cyberapolcalypse2023/blockchain/blockchain_navigating_the_unknown/solution2.py", line 6, in <module>
    print(w3.isConnected())
          ^^^^^^^^^^^^^^
AttributeError: 'Web3' object has no attribute 'isConnected'. Did you mean: 'is_connected'?

yeah all of that is BS, screw python learn nodejs like this:

const Web3 = require('web3');
const abi = [
    {
        "inputs": [
            {
                "internalType": "uint256",
                "name": "version",
                "type": "uint256"
            }
        ],
        "name": "updateSensors",
        "outputs": [],
        "stateMutability": "nonpayable",
        "type": "function"
    },
    {
        "inputs": [],
        "name": "updated",
        "outputs": [
            {
                "internalType": "bool",
                "name": "",
                "type": "bool"
            }
        ],
        "stateMutability": "view",
        "type": "function"
    }
];
const contractAddress = '0x7b92F8C66e04b3cc857218EeFaA433eab35F10d0';
const rpcUrl = 'http://188.166.152.84:30963';
const web3 = new Web3(new Web3.providers.HttpProvider(rpcUrl));
const contract = new web3.eth.Contract(abi, contractAddress);
const version = 10;
contract.methods.updateSensors(version).send({ from: '0x5Bb68dc361f80fabB55916189af56d850d98FFDE' }, (error, txHash) => {
    if (error) {
        console.log('Error:', error);
    } else {
        console.log('Transaction hash:', txHash);
    }
});

to get the flag

Published on : 27 Mar 2023