Ethereum Blockchain | "EtherHide" (Hackcon2018 CTF)

Key Takeaways

what's up guys this is a video right up for the challenge ever hide for 40 points the miscellaneous category of hakkon 2018 capture the flag so this challenge from here is my friend heard about the ethereum blockchain and thinks it to save this place to hide stuff prove him wrong and it gives us a network to would do whatever with and a contract address I didn't actually end up using this at all I didn't even realize it was there to be completely honest I am NOT in authority to really be going over this challenge I just kind of poked around and found it eventually so what I had done not knowing a whole lot about like cryptography like crypto currencies etc etc I was assuming okay a theory was a kind of like Bitcoin and it is a crypto currency I know there's a Bitcoin wallet so is there such thing as an ethereal wallet I googled that and I found my hair wallet or my ether-wall calm and it looked like I was able to change up at the very top right the network that I was on originally I was just on eth maya thorough home but i was able to move it down and I saw that if I choose Rob's 10 which is that network that it specifies Rob's 10 test network I couldn't tell the difference between Rob Stan my a third wold and Robson and Fuhrer so I was assuming the second one was their test network so I just switched over to that and then I went to view wallet info because it didn't look like I wanted to create a wallet I just wanted to find some other wallet and it asks okay how would you like to access a wallet and I look through this list it looked like I could supply an address and that's what I had I had an address so I copied and pasted of what I had in there could view that balance and it gives me whatever this is it looks like okay a QR code I could have decoded that but it would just give me what we've already seen so it said okay I can look at the transaction history over at this URL so I went ahead and tried to take a look at that at this point I'm looking at things that I don't understand and don't know what they are but it looked like okay these are transactions these are things happening during the time of the competition and it gave me a value as to whether or not there was either going through or like actual money working with it and I saw this one that was one decimal 337 either and that looked like leet so I thought okay that has to be a lead for a flag or something so I went ahead and clicked on that I scrolled down and it looked like okay check data string data and there's some stuff here after I looked through it in ok I got the note that this value looks like hex so what I did was I went ahead and checked out what that hex might be by Python right I did that dot decode hex and there was the flag with an old by character at the very end so ok let's go ahead and take that and use that as our get flag script because we've solved the challenge just now we we did it already so simple miscellaneous category but we can remove there's no bites there that is a little bit of the reconnaissance that I had done or at least what I kind of poked around with trying to bang my head against the wall until I knew what I was really working with there I totally put the wrong shebang line so simple challenge but finding your way and poking around and if you wanted to learn more about blockchain but I know parents ease but I didn't particularly want to at the time it was still easy enough to find the flag just like that so we can mark that challenge as complete you could submit it for points however unfortunately the game is no longer live if you would like to play other cat flip-flop competitions please join our discord server link in the description super quick shout out to the people that support me on patreon thank you guys so much you're the best $1.00 or more on patreon a month we'll give you a special shout out just like this at the end of every video five dollars or more on patreon if you early access to everything there at least on YouTube before it goes live cuz I normally record in bulk and then gradually release them if you did like this video please do that like comment and subscribe join the discourage server link in the description it's a cool community of CDI flavours programmers and hackers and I'd love to see you guys in the next video bye