All aboard the internship – whispering past defenses and sailing into kernel space

Previously, we have already published Sander’s (@cerbersec) internship testimony. Since this post does not really contain any juicy technical details and Sander has done a terrific job putting together a walkthrough of his process, we thought it would be a waste not to highlight his previous posts again.

In Part 1, Sander explains how he started his journey and dove into process injection techniques, WIN32 API (hooking), userland vs kernel space, and Cobalt Strike’s Beacon Object Files (BOF).

Just being able to perform process injection using direct syscalls from a BOF did not signal the end of his journey yet, on the contrary. In Part 2, Sander extended our BOF arsenal with additional process injections techniques and persistence. With all this functionality bundled in an Agressor Script, CobaltWispers was born.

We are considering to open source this little framework, but some final tweaks would be required first, as explained in the part 2 blog post.

While this is the end (for now) of Sander’s BOF journey, we have another challenging topic lined up for him: The Kernel. Here’s a little sneak peek of the next blog series/walkthrough we will be releasing. Stay tuned!

KdPrint(“Hello, world!\n”);

When I finished my previous internship, which was focused on bypassing Endpoint Detection and Response (EDR) software and Anti-Virus (AV) software from a user land point of view, we joked around with the idea that the next topic would be defeating the same problem but from kernel land. At that point in time I had no experience at all with the Windows kernel and it all seemed very advanced and above my level of technical ability. As I write this blogpost, I have to admit it wasn’t as scary or difficult as I thought it to be. C/C++ is still C/C++ and assembly instructions are still headache-inducing, but comprehensible with the right resources and time dedication.

In this first post, I will lay out some of the technical concepts and ideas behind the goal of this internship, as well as reflect back on my first steps in successfully bypassing/disabling a reputable Anti-Virus product, but more on that later.

About the authors

Jonas is NVISO’s red team lead and thus involved in all red team exercises, either from a project management perspective (non-technical), for the execution of fieldwork (technical), or a combination of both. You can find Jonas on LinkedIn.
Sander is a cyber security student with a passion for red teaming and malware development. He’s a two-time intern at NVISO and a future NVISO bird.

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