A Week with Saumil (aka "The ARM Exploit Laboratory")

Last month we downed tools for a week as we hosted a private, on-site version of the well regarded “ARM Exploit Laboratory” (by Saumil Shah). The class is billed as “a practical hands-on approach to exploit development on ARM based systems” and Saumil is world respected, delivering versions of the class at conferences like 44con, Recon and Blackhat for years.

It.absolutely.delivered!

With a quick refresher on ARM assembly and system programming on day-1, by day-2 everyone in the class was fairly comfortable writing their own shellcode on ARM. By the end of day-3 everyone was comfortable converting their payloads to ROP gadgets and by day-4 everybody had obtained reverse shells on emulated systems and actual vulnerable routers and IP-Cameras. Without any false modesty, this is due to Saumil's skill as an educator much more than anything else.

Pre-Class Preparation


While our Canary is used by security teams the world over, many people in the team have backgrounds in development (not security) so we felt we had some catching up to do. A few months before the class, we formed an #arm-pit slack channel and started going through the excellent Azeria Labs chapters and challenges. (It’s worth noting that Saumil's class managed to work for people on the team that were not taking part in our weekly #arm-pit sessions, but those of us who did the sessions were glad that we did anyway).

A special shout out to @anna who didn’t actually attend the ARM exploitation sessions but made sure that everything from food and drinks, to conference room and accomodation were all sorted. An echo that great preparation made for a great experience. Thank you @anna.

The Class


We’ve all sat in classes where the instructor raced ahead and knowledge that we thought we had proved to be poorly understood when we needed to apply it. As the course progressed, each new concept was challenged with practical exercises. Each concept needed to be understood as the following concepts (and exercises) would largely build on the prior knowledge. And in this fashion, we quickly weeded out gaps in our knowledge because practically we could not apply something we
did not understand.

The addition of shellcode-restrictions (and processor mitigations) tested a particular way of thinking which seemed to come more naturally to those of us with a history of “breaking” versus “building”. The breakers learned some new tricks, but the builders learned some completely new ways of thinking. It was illuminating.

The class was choc-full of other little gems, from methodologies for debugging under uncertainty to even just how slickly Saumil shares his live thoughts with his students via a class webserver (that converts his ascii-art memory layout diagrams to prettier SVG versions in real time)





It’s the mark of an experienced educator who has spotted the areas that students have struggled with, and has now built examples and tooling to help overcome them. We didn’t just learn ARM exploitation from the class, it was a master class in professionalism and how to educate others.

Where to now?


A bunch of people now have a gleam in their eyes and have started looking at their routers and IOT devices with relish. Everyone has a much deeper understanding of memory corruption attacks and the current state of mitigation techniques

Why we took the course?


Team Thinkst is quite a diverse bunch and exploitation isn’t part of anyone’s day job. We do however, place a huge emphasis on learning, and the opportunity to dedicate some time to bare metal, syscalls and shellcode was too good to pass up. We’ve taken group courses before, but this is the first time we’ve felt compelled to write it up. Two thumbs up! Will strongly recommend.

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