hackfulogo

First off let me just say a big thank you to the MWR guys who put this CTF together, usually I don’t partake in CTFs because the skillset required is usually out of my grasp (IANAP).

To have developed this CTF in a manner that allows people who do not work with crypto/hackz0r wizardry to still have a chance of solving the problems is awesome! I didn’t solve all of the problems, but I did spend far too much of my free time and apologise to the many bars I had to let down during that time. After this writeup I shall resume my social responsibilities ;)

Each of the various problems took my many hours of frustrating, wallpunching, facepalming and omgnoobing to complete, however I will just go over the solutions to each of them without the hours of frustration — the tl;dr of each one if you will.

Challenges:

Challenge 1 ( GUASS RIFLE ) — A book cipher requiring you to parse various words from lines in books
Challenge 2 ( RADIATION POISONING ) — An LSB Stego QR code that needed to be decoded and then parsed
Challenge 3 — Not completed
Challenge 4 ( FACSIMILE ) — A audio fax that needed to be decoded
Challenge 5 ( GREEN SKIN ) — A literal jigsaw puzzle representing 4 sides of a puzzle piece with 3 characters
Challenge 6 ( WHIRLPOOL ) — A multiple times rotated image that needed to be ‘unrotated’
Challenge 7 ( SCORCHED EARTH ) — An Office document with a weak password
Challenge 8 ( SMOG AND SMOKE ) — A Modified playfair cipher that needed to be recronstructed based on solar systems
Challenge 9 — Not completed
Challenge 10 — Not completed

If you have the writeup to challenges 3/9/10 please let me know so I can link to them!

GitHub

All the challenges/instruction text and solutions are available on the following github: https://github.com/AndrewMohawk/HackFu2016

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This blog post will discuss the implementation of Codegrabbing / RollJam, just one method of attacking AM/OOK systems that implement rolling codes (such as keeloq) — these systems are commonly found on modern vehicles and entry systems such as gates and garages. This technique has been used and spoken about for a number of years (Marko Wolf describes it in “Security Engineering for Vehicular IT Systems” from 2009).

However the advancement in easy to use and cheap hardware has made this a readily available research path for almost anyone. Samy Kamkar showed it at Defcon 2015, you can read about that and his device at http://www.wired.com/2015/08/hackers-tiny-device-unlocks-cars-opens-garages/. This blog entry will be more discussing the integral parts of how it works and how easy it is to do.

I was optimistic that the 2015 talk @elasticninja and myself did at zacon on this topic would be published so that I could lazily just link to the video instead of having to write it up, but alas, here we are! ;)

Naturally its important to have a spoiler before the long boring text. Here is a video carefully crafted by my friend Roelof Temmingh showing us opening a VW car with two YS1 (YardStick One):

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Introduction

Its been absolutely ages since I’ve posted anything on the blog, not that I havent been doing things, just really not many things I felt good enough to write an entry about. I got a lot of feedback regarding my previous entry about Hacking Fixed key remotes and I decided to build on that slightly.

One of the pains of the previous method was that it was a rather tedious to do the following:

* Finding the key for the remote essentially it was broken into:

* Finding the signal with RTLSDR
* Saving demodulated .wav
* Running a script to decode that audio
* Replay remote with RFCat

* Transmitting the remote also meant another piece of hardware (RFcat) and then taking the signal from the decoded script into a format RFCat understands.

So much like the sex pistols album I am also going to be flogging a dead horse, this time the AM/OOK one. In this blog post I will explore discovering signals as well as replaying them with RFCat.

YardStickOnePacket

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The ZaCon badges were a ton of work on the hardware side (see ZaCon V Badge [1/2]: Build Time), however they provided their own challenges on the software side as well.

Since my knowledge of chipsets only extended to the Arduino the badges are essentially a complete Arduino without the UBS->FTDI breakout. This means that each badge includes an Arduino bootloader which is _really_ nice if you are coming from an Arduino background or simply have an Arduino and want to play.

The idea behind the badges was that they would provide a means of tracking communication between individuals at the conference. Additionally I wanted this information transmitted to a central location so that it could be stored and visualised (yes yes, Maltego and all). Additionally because people would be moving around I needed to create a ‘mesh network’ of sorts so that anytime someone came into range of any other badges they would be automatically be part of the network. This blog entry is going to cover how the badges did this and the challenges faced, if you are not interested make like a heartbleed and go away.

Eye Candy:

Here is a video of a few of the black badges communicating to each and flashing for all the valid messages received:

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I realise I should have done this entry a little sooner, but as everyone should be well aware of by now, I am lazy. Also I moved to Cape Town just after ZaCon V which proved rather time consuming! Please note this is gonna be a first of 2 big entries on them so if you don’t like reading, pull up now.

Overview

zaconPic
(pic from https://twitter.com/DavidBisschoff/status/401460570911956993/photo/1)

One of the highlights of the annual Las Vegas pilgrimage for me has always been the electronic badges, whether it’s for defcon, ninja networks or custom badges that people have built for their hackerspaces. I especially enjoy the ones that are a little more complex (more than just lights) and are hackable. I have always been in awe of security researchers such as Adam Laurie, Zak Franken, Michael Ossman, At1as and the other hardware hackers.

For ZaCon V ( www.zacon.org.za ) I built some electronic badges for the conference that are based on an Arduino framework (at least using an ATMega328 with an Arduino Bootloader) and communicate to each other via 433Mhz RF (the same that is used in remotes). The idea with the badges was to have a way to see who was interacting with whom and show it in a visual representation (Maltego — yes yes, man with a hammer etc). Additionally I needed the badges to be cheap as.. well… I am cheap :)

The badges took about 3 months to go from breadboard to finished and a large majority of that time was spent learning how electronics work (and don’t!). This however was not my first attempt at building badges, for the last 3 years I have built a design on a breadboard and then basically done nothing with it (apart from make a shakey cam video at 3am and suggest the idea).

A lot of the design actually came from me wondering around hobbyist electronic stores on the internet and coming across two really cool things namely, very cheap communication in the form of 433mhz RF chips and Nokia 5110 LCDs (also cheap :P ).

I ordered a few of the screens and RF kits and started tinkering- having a display connected to my Arduino brought all kinds of warm and fuzzy feelings. Next I started playing with the 433Mhz, originally thinking that the badges would only receive a simple message, something like who was currently speaking, from a PC near the stage. Roelof looked at it and suggested that this idea was boring and if I really wanted to do something cool I should make all the badges talk to each other. And so the tinkering began.

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