Xeno Kovah
xenokovah.bsky.social
Xeno Kovah
@xenokovah.bsky.social
Interested in reverse engineering, firmware, bluetooth, trusted computing, and training. Founder of OpenSecurityTraining2 https://ost2.fyi
A ton of great info here about what Apple does for their secure boot chain: “A Reverse Engineer’s Anatomy of the macOS Boot Chain & Security Architecture” stack.int.mov/a-reverse-en...
A Reverse Engineer’s Anatomy of the macOS Boot Chain & Security Architecture
1.0 The Silicon Root of Trust: Pre-Boot & Hardware Primitives The security of the macOS platform on Apple Silicon is not defined by the kernel; it is d...
stack.int.mov
November 24, 2025 at 11:31 AM
I was invited to give a talk at VUSec while I was in AMS for HWIO. So of course I talked to the students about the value of grabbing some vocational skills from @opensectraining.bsky.social , to boost their resumes.
November 24, 2025 at 1:19 AM
Meh, I don’t particularly feel like breaking this up into threads for more size-limited platforms like this: infosec.exchange/@xenokovah/1...
Xeno Kovah: "Misc story time: tldr: I've been collecting secu…" - Infosec Exchange
Attached: 4 images Misc story time: tldr: I've been collecting security conference stickers for 20+ years and just now got around to using them ¯\_(ツ)_/¯ I'm not the kind of person to put stickers on my laptop. This means that for 23 years (apparently), when I got stickers from a conference, I kept them, put them in a bag, moved them from house-to-house, but never actually did anything with them. Until now. I finally found a usage; which is decorating the otherwise-sketchy-looking metal ammo case which @VeronicaKovah & I are now using to carry phones with us to trainings. We watched some videos on youtube that make it seem like those LiPo fire-protection bags would do a whole lot of not-much in the event that a fire broke out on one of the batteries. But a simple metal box seemed to do a lot better in terms of containing the flames. So we of course expect that airport security will always stop us when traveling with them (though at least this time our TSA pre-check status seemed to give us a pass on the way out). But the expectation is that contrary to what you might thing, adding hacking conference stickers will actually be disarming, rather than alarming, with security personnel - at least when compared to the alternative of seeing a raw ammo canister ;) The oldest sticker seems to be from DEF CON 10 (X), circa 2002 (my first DEF CON was 8 FWIW). In general I don't seek out stickers, but I do think the BadBIOS and "I want to believe" ones are things I probably got from Joe Fitz as they were of-the-moment and relevant to my interests. (If you're not familiar with the latter, it's from a very FUDish cover article [1]). I could have completely filled them, but I left a little bit of space for the future. Check out the larger pics for a potential stroll down memory lane. (RIP Shmoocon, Hackademic.info, NoSuchCon. Memento mori conference organizers ;)) #DEFCON, #BlackHat, #ShmooCon, #BlueHat, #RingZer0, #HackLU, #HardwearIO, #DistrictCon, #HackFest, #NoSuchCon, #DeepSec, #HITB, #HackersOnTheHill [1] https://www.bloomberg.com/news/features/2018-10-04/the-big-hack-how-china-used-a-tiny-chip-to-infiltrate-america-s-top-companies
infosec.exchange
November 24, 2025 at 12:42 AM
Thanks to everyone who attended my hardwear.io workshop about Blue2thprinting! The ~8.5h free class where you can learn more is at ost2.fyi/bt2222 . Once you finish that, you'll be eligible to join the 🏴‍☠️🔵BlueCrew🔵🏴‍☠️!
November 23, 2025 at 11:50 PM
Reposted by Xeno Kovah
I chatted with @hex-rays.bsky.social about how I found my place in the security industry, how @blackhoodie.bsky.social came to be, what our goals are and why community matters so much. hex-rays.com/blog/blackho...
BlackHoodie Interview: Building Community, Opportunity, & Confidence
BlackHoodie founder Marion Marschalek shares her journey from early challenges to creating a global, inclusive reverse-engineering network.
hex-rays.com
November 18, 2025 at 6:02 PM
Real ones post their slides before their talk (or at least very shortly thereafter) ;)

Slides & materials for HWIO NL talk later this week:
“Reverse engineering Realtek RTL8761B* Bluetooth chips, to make better Bluetooth security tools & classes”

darkmentor.com/publication/...
Reverse engineering Realtek RTL8761B* Bluetooth chips, to make better Bluetooth security tools & classes | Dark Mentor LLC
We hold this truth to be self-evident&#58; SUFFERING BUILDS STRENGTH! In this talk I will walk you through the trials, tribulations, and triumph(!) of the worst debugging setup I've ever hacked together, which I used to reverse engineer the Realtek RTL8761B* family of Bluetooth chips.<p>This work was done because Bluetooth security tools are in an abominable state. We use "CSR4" (Cambridge Silicon Radio) dongles that don't support packets newer than Bluetooth 4.0 (released in 2010!), just to be able to spoof the Bluetooth Device Address (BDADDR) for MitM attacks.<p>Veronica Kovah & I have been creating Bluetooth security classes for <a href="https://ost2.fyi/">OpenSecurityTraining2</a>. And we wanted to use better hardware; ideally something that supports BT 5.4 (released in 2023). So I bought a bunch of cheap dongles off Amazon, and found that most of them used the same RTL8761B chip. So the goal was clear&#58; at a minimum, figure out a way to spoof the BDADDR on these dongles. But I also a set out a nice-to-have stretch goal - to figure out how to use these dongles to send custom LMP packets (which are architecturally not meant to be under full user control.) That way, could replace a bulky and expensive $55 dev board (that is only used for BT Classic), with a cheap and small $14 USB dongle (which has a better antenna to boot!) This would make Blue2thprinting (released at Hardwear.io 2023), and thus Bluetooth reconnaissance & vulnerability assessment, cheaper & better.<p>Bloodied (but not broken) by the ordeal, I achieved my goals and stretch goals. And given that there are no public descriptions of how Realtek Bluetooth chips work, I look forward to sharing hitherto-unknown information about how to navigate and understand these mostly-16-bit-MIPS-code systems. And I'll discuss how their ROM-"patch"ing firmware update mechanism works, how you can patch it to change its code too, and the security implications thereof.
darkmentor.com
November 17, 2025 at 6:46 AM
Organic chemists:
November 17, 2025 at 6:44 AM
I'm looking forward to taking this class as a student, since I've always wanted to learn more about QEMU, since lots of security research projects work by augmenting it. And because it’s often used to run firmware too (from UEFI to embedded). If that's you too, take it too!
November 14, 2025 at 12:43 PM
Reposted by Xeno Kovah
📢Call for beta testers!📢
The "Architecture 1901: From zero to QEMU - A Gentle introduction to emulators from the ground up!" course by Antonio Nappa @jeppojeps.bsky.social will begin November 28th. Sign up here: forms.gle/LUXaThn4YSYS...
Architecture 1901: From zero to QEMU - A Gentle introduction to emulators from the ground up!
Enter the email you have used / will use when registering for beta.ost2.fyi. This will be used to enroll you in the beta class if you are selected. If your account does not exist at the time enrollmen...
forms.gle
November 14, 2025 at 12:10 PM
Reposted by Xeno Kovah
Squeeeee 🥳 I'll be teaching my Advanced Linux Malware Reverse Engineering class at RE//verse conference in 2026!! MORE Linux APT insides and peculiarities😍🥰🤩Pls share if you can🙃
shop.binary.ninja/products/re-...
RE//verse 2026 Training - Advanced Linux Malware Reverse Engineering with Marion Marschalek
This fast-paced 3-day training explores Linux internals and Linux binary analysis techniques, before jumping right in with common Linux malware. Work through advanced samples, Linux software protectio...
shop.binary.ninja
November 12, 2025 at 6:59 PM
‘The finding suggests that at current scales, language models treat “2+2=4” more like a memorized fact than a logical operation.”

Same, AI, same… I did really good in HS math, through calculus 2, because I’m really good at memorization. Linear algebra for EE in college proceeded to kick my ass…
November 11, 2025 at 11:31 AM
November 10, 2025 at 8:59 PM
Got the slides down from 350 to a lean 173! Finally going the right direction! I suspect I’ll land around 160+talking fast…
Added 24 summary slides to see how much work I have left to do…current slide count is 266. Thoughts and prayers appreciated 💀 (but realistically this deck will form the basis for a future “RE like me: Realtek edition” class)
The good news is also the bad news: 2 days of slide-making and I’m over 100 slides…to describe the first 5 days of the work 😬 There’s no way I’m going to be able to include everything in the talk. I’ll post a “Kovah Cut” on the DarkMentor website like in the past, but may have to break into 2 talks
November 10, 2025 at 8:58 PM
Real-talk: I’ve gone from updating every half-year to almost 1.5 years! I’ll need people to start submitting pull requests for changes to add or update new talks, or it’s very likely this timeline will come to an end. Anyone who’d like to join as a co-maintainer should LMK.
🧵⬇️Low level security timeline update!⬆️ 2025-11-09 Part 1
After over a year, I've finally updated the Low Level PC/Server Attack & Defense Timeline! darkmentor.com/timeline.html The 2025 talks are in this thread, and pre-2025 will be next time.
👇
Low Level PC/Server Attack & Defense Timeline — By @XenoKovah of @DarkMentorLLC
darkmentor.com
November 10, 2025 at 11:30 AM
🧵⬇️Low level security timeline update!⬆️ 2025-11-09 Part 1
After over a year, I've finally updated the Low Level PC/Server Attack & Defense Timeline! darkmentor.com/timeline.html The 2025 talks are in this thread, and pre-2025 will be next time.
👇
Low Level PC/Server Attack & Defense Timeline — By @XenoKovah of @DarkMentorLLC
darkmentor.com
November 10, 2025 at 11:28 AM
Reposted by Xeno Kovah
The recording of my talk at OSFC 2025 earlier this year is now live at:

www.osfc.io/2025/talks/t...
November 5, 2025 at 7:08 PM
New life philosophy (x.com/xenokovah/st...) is helping me understand my general anti-CTF sentiment and why I feel like CTFs are a waste of peoples’ lives: “Solve *problems*, not puzzles”. If they’re the same, great. But I’ve seen lots of CTF *puzzles* which don’t teach problem solving.
November 5, 2025 at 10:32 PM
It's awesome to see companies like @binarly.bsky.social helping support OST2 so it can keep bringing free training to the world! (This could/should be your company too! :))
We are happy to announce that @binarly.bsky.social has renewed their 🥇Gold-level sponsorship of #OST2!

Learn more about what they do in firmware & supply chain security here: ost2.fyi/Sponsor_Bina...
November 3, 2025 at 11:59 AM
We finally have a place to put all the firmware security & related classes, regardless of whether the firmware is server, desktop, embedded, or mobile!
This year @binarly.bsky.social has also expanded their sponsorship to the creation of a new #OST2 Firmware Security Learning Path!

ost2.fyi/OST2_LP_FWSE...
November 3, 2025 at 11:55 AM
@districtcon.bsky.social looks like it has a pretty great lineup of talks and speakers this year (districtcon.org). I’ll be there too, talking about my new Realtek Bluetooth chip RE work
October 28, 2025 at 10:36 AM
Reposted by Xeno Kovah
You could use the OST1 Rootkits class (opensecuritytraining.info/Rootkits.html) as a starting template, since that's the whole point of making the materials under CC licenses. Xeno Kovah isn't planning on updating it as he's off in Bluetooth world now.
Rootkits
opensecuritytraining.info
October 27, 2025 at 11:24 AM
Reposted by Xeno Kovah
Periodic call for volunteers: We're looking for someone to teach classes on stealth malware, such as rootkits, bootkits, and other security-evading software.
October 27, 2025 at 11:23 AM
October 27, 2025 at 11:11 AM
🧵I created a complimentary repo to Antonio's, that's focused specifically on common security-relevant HCI Vendor-Specific Commands and getting them documented in a useful machine-readable way (Scapy definitions for now) github.com/darkmentorll...
GitHub - darkmentorllc/BT_Security_VSC_DB: This repository contains information about Bluetooth HCI Vendor-Specific Commands (VSCs) which are known to be security-relevant.
This repository contains information about Bluetooth HCI Vendor-Specific Commands (VSCs) which are known to be security-relevant. - darkmentorllc/BT_Security_VSC_DB
github.com
October 27, 2025 at 11:09 AM
Reposted by Xeno Kovah
Y'all fantastic news! Save the date, @blackhoodie.bsky.social will be at @districtcon.bsky.social this year 😱 the fantastic crew has offered to host us for a day of Malware Reverse Engineering! @synapticrewrite.bsky.social and myself will be hosting a training for women by women on January 23rd!!
October 26, 2025 at 7:37 PM