With our partners* and sponsors* we are organizing CCTF for the 5th and 6th time in 2021 May. Just like at the previous events, we are providing a guide for beginners. This helps you to get started with hacking Ethereum smart contracts.
It is recommended to move step by step. Follow this guide and you will understand the basic logic of cryptocurrencies, blockchain and smart contracts.
CCTF Vol6. starts on 27th May, at 8:35 and finishes at 17:00.
Cryptocurrencies such as Bitcoin and Ethereum allow you to handle digital assets on decentralized networks. There is no central authority which can censor or block your account.
Accounts are stored in digital wallets, eg. “ethereum wallet”. If you use “Metamask ethereum wallet”, you have full access your wallet, meaning only you have the private keys that are needed to make transactions. The public part to share from this wallet is only your ethereum address. In fact, when you send 1 Ethereum to another person, to his address (into her/his wallet) what happens is that you sign a transaction with your private key that this 1 Ethereum no longer belongs to you, but to the other address. That’s it. The transaction gets propagated on the Ethereum network and miners verify that transaction.
Here are the screenshots in 3 steps of sending 1 Ethereum to another address:
No central bank or complicated legal processes: you have the power to make transactions anywhere in the world fast and with a few clicks. Also, none can block it. Follow this guide further and we will create your first Ethereum wallet.
But why Ethereum? Because you can do more with transaction: engage with smart contracts. Imagine coding a program that you upload to a decentralized network, it gets stored there and can be called anytime in the future. Or imagine a business that does not have physical contracts, just virtual ones on the blockchain. All these are secure as long as somebody successfully cheats/hacks the network consensus or exploits vulnerabilities in the smart contrats itself. It may sound complicated for the first, but it is not rocket science. Let’s start creating your wallet.
Creating a wallet
Most of the Ethereum hacks (breaking smart contracts, accessing accounts without or with weak authentication, phishing) do not require more than a web browser and a bit of coding skills. For the start, only a FireFox or a Chromium/Chrome web broswer is enough with the MetaMask addon. You can connect this wallet to the Ethereum test networks and play around.
Open your FireFox or Chromium browser and install the MetaMask extension: https://metamask.io/. Currenly, MetaMask is the most commonly used software by end users to interact with Ethereum contracts (these are called “dapps”/”decentralized apps” too).
After installing the extension, it either automatically opens up or you can open it from the top right bar in your browser.
The first step of using MetaMask is to generate your wallet. At this point you are asked to provide a password. Preferably, use a passphrase that is like a sentence, but does not include words from dictionaries (example: “HaxxA11co|ns”). Choose wisely.
Move on and read the phishing warning carefully!
Finally you need to make sure the secret backup words that allows restoring the wallet is secured: of course in a place only you can access and see. For playing you can just use paper, but for real wallets with high balances it is better to write the words on something that can survive even if your house burns down (eg. MyCryptoSeed)
All is set. Now you have an Ethereum wallet and inside: an Ethereum account.
Changing networks and faucets
MetaMask allows you to change between Ethereum networks. Please change to Ropsten Test Network and remember that the game will be played from there.
Faucets provide free Ethereum for you on the test networks. Now it is time to get some from: https://faucet.ropsten.be/ (if it does not work, you can find other Ropsten faucets online or contact the CCTF organizers).
Congratulations, you are ready: time to get into code and hacking!
Coding and compiling a smart contract
Let’s compile an example smart contract and interact with it. Open https://remix.ethereum.org/ where you get an example contract written in Solidity language. Remix website has an inbuilt compiler and if you click on “Start to compile” it will compile the code. Now you can swith to the “Run” tab. If you have MetaMask running, then you should see “Injected web3” in the environment.
MetaMask injects the so called web3.js into each website you visit, that way the website can communicate with MetaMask (also think about that: is it a good idea to inject to all sites?).
Deploying a smart contract
Make sure your MetaMask account is unlocked, switched to “Ropsten” and you got a coin from the faucet. Then click on “Deploy”.
MetaMask pops you up a transaction which is actually the deployment of the compiled smart contract to the Ropsten Ethereum test network. Now you may wonder what “gas fee” is? Gas limits the computational efforts of the smart contract, meaning you cannot deploy a computational heavy infinite loop for free. You can only use a smart contract if enough gas is provided. If you are ready, click on “Confirm”.
Wait until the transaction changes from “Pending” state to “Confirmed”. This is indicated in MetaMask. The network needs time to make sure your conract is broadcasted and mined successfully. If you click on the transaction, you have a button “View transaction on Etherscan”: click on it and have a look at what happened.
Interacting with the contract functions
By going back to https://remix.ethereum.org/ you can start playing with the “Deployed Contracts”, under the “Run” tab. You can call the deployed smart contract’s functions one by one. Each call you initiate takes a transaction. The executed code runs on all of the Ropsten Ethereum nodes.
Congratulations, you have compiled your first smart contract and interacted with it.
You have seen the very basics and it is time to think about what else can go wrong… Weak passwords, MetaMask seeds all over the place, programmers making mistakes in smart contracts that you can call, logic, broken crypto problems and so on.
Looking for meeting other people who are into crypto*? Wants to find the best place to start your blockchain business? Awalcon and the HODLbag project shares the best places to get started. If you are an enthusiast, already have a project, looking for investors or just a beginner who wants to learn and meet interesting people: this is what you need to know.
EcoX Networking Events
Every Tuesday, you have the chance to meet people from different backgrounds, many of them are into crypto*. Just get there and be brave to start discussions with people you do not know yet!
Dubai allows crypto businesses to set up in free zone
Just as the heading says, things are moving on in the free zone.
An economic free zone in Dubai has opened for businesses that are offering, issuing, listing and trading crypto assets. The Dubai Multi Commodities Center (DMCC) signed the initial agreement with the Securities and Commodities Authority (SCA) to allow licensing for firms that deal with crypto assets.
The Awalcon HODL Bag team visited Dubai for finding new possibilities, inspiration and attending the Global Blockchain/DeFi congress which took place between 2021.02.09.-10.
The whole trip was a positive experience from the point of meeting new people, learning more about DeFi projects and discussing with investors (VCs, Private Equity Firms, Family Offices and High Networth Individuals). Though we are not seeking financial support, advice is always welcome from individuals who have already created projects that work on the long run.
The days we have spent in Dubai truly gave us inspiration and new ideas to push our IDeaLs (Indpendent Decentralized Life System) further. We are very soon making the HODL Bag system public and accessible for everyone who is interested.
Awalcon OÜ has also been fully initialized in Estonia (registration code 16156552). That means we are ready to sell the HODL Bags and also ready to work for the system.
We take decentralization serious: you will be able to use the first functions in this HODL Bag NFT smart contract with just your MetaMask app and the frontend will also be runable from any computers, not centralizing all the contact interactions to a single website.
We are looking forward to keeping in touch with all our new friends.
In Hungary, most of the companies are just getting started with information security. Our goal is to support them to implement more secure systems, both from human and technical point of views: IT security awareness, policies, audits, penetration testing, cryptography and the Awalcon Certification system.
The presentation covers an introduction to IT and Information Security. We start from the topic of homeoffice and arrive to enterprise networks.
The task was to somehow break a specified website. The HTML markup of the website contained the text “Figwheel”. A quick web search will reveal that Figwheel is a software package for developing websites — live¹ — in the Clojure programming language.
On the website, the only item of interest was the link anchored to the text “do you even REPL, bro?”: the URL contained an argument of “(cons 1 2)”, which looks like Clojure code (a lot like Lisp). Along with the challenge’s name of “Don’t be eval”, these all gave the suggestion that the web request’s single parameter was taken as Clojure code to be evaluated, and indeed it was.
Clojure has access to the full Java ecosystem, including IO functions. By sending in appropriate code snippets (in the URL parameter), it was possible to list the contents of the current directory; it contained a file called “flag.txt”. Then that file could be printed, which contained the flag.
For this challenge, a host was specified, and it was suggested that one ought to use Netcat. It was also blatantly stated that one should try overflowing the “meaning of life” (i.e. 42). The solution was to send an arbitrary string exactly of length 43 (not more, which might be weird, but is realistic), over a plain TCP connection; this revealed the flag.
On top of that — and this is something that even the creator of this challenge didn’t think about —, one could discover that the service served at most 1 client at a time, denying other connections while one is open. This permitted a shrewd contestant to prevent other contestants from even attempting to solve this challenge thereafter, by leaving a connection to the server hanging without submitting anything — it wasn’t me! :trollface.jpg:
Note from six for this solution: it was a wargame! 🙂
We have received many requests for the CCTF game writeups. Here is the first one, the challenge was called “BIPolognese”. Be careful, spoilers follow.
BIPolognese (100 points)
Crypto Wojack (beginner)
Crypto Wojack was considerate again and made a cold backup of his wallet seed so Bogdanoff can't hak it again.
Meanwhile, he was lost in eating ₿10.000 pizza.
Look at that picture! Can you get the account address?
CCTF is organized the third time, now for Bday 3.0 (Blockchain Day) which is one of the largest cryptocurrency related event in Central-Europe.
CCTF is a “Capture The Flag” game where the participants need to hack realistic challenges related to cryptography and cryptocurrencies. The best ones will get rewarded by some presents and QARK tokens, offered by QAN.
What about the previous CCTF events? An archive will be created including all the three of them after the last finishes. It will be available on the CCTF’s website.
Who creates these events? The founder of the CCTF project is six from Awalcon who initiated it in 2019 by calling fellow hackers into the project. It is a joint project where the creators include not just Awalcon, but also members from H.A.C.K. and this year Silur from QAN.