Gynvael Coldwind 🐈

4.2K Followers
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211 Posts
security researcher/programmer ⁂ previously security team @ Google ⁂ Dragon Sector CTF founder/player ⁂ technical livestreamer ⁂ slide maker ⁂ he/him
YouTube[EN]https://www.youtube.com/@GynvaelEN
YouTube[PL]https://www.youtube.com/@GynvaelColdwind
Bloghttps://gynvael.coldwind.pl
Twitterhttps://twitter.com/gynvael

RE: https://infosec.exchange/@PagedOut/116362415442678434

This article (recommended if you're learning RE!) reminded me of a GOATed FPGA bistream reversing task from Google CTF (GPURTL by Robin), where the key to solving it for me was observing the pattern of changing bits in FPGA's registers. The pattern itself was enough to pinpont the exact algorithm.
@liveoverflow made a video about this task: https://www.youtube.com/watch?v=3ac9HAsfV8c

https://www.youtube.com/watch?v=gJM9pZydzVg ← my new old talk was released as a standalone; it's a fun story of how you go from being able to write '2' (0x32, 1 byte) anywhere on the FS to full RCE with admin/root privs
CTF In A Box ? The Weirdest NETGEAR Network Switch 2021 Exploit Chain - Gynvael Coldwind

YouTube

My second article in Paged Out! #8 was about the architecture of the terminal emulator on Linux - it's a really obvious thing until you start digging into details, as usual.

Web viewer: https://pagedout.institute/webview.php?issue=8&page=43&article=Linux+terminal+emulator+architecture
PDF download: https://pagedout.institute/?page=issues.php

Pwndbg 2026.02.18 is out! Enhance your GDB or LLDB experience!

We visualize branches in nearpc, synchronize your decompiler (IDA/Binja/Ghidra) via decomp2dbg, annotate stack variabless from debug info or decompiler, support new Linux kernel debugging commands - for tracing SLUB allocs/frees or dumping tasks information.

See what's changed in: https://github.com/pwndbg/pwndbg/releases/tag/2026.02.18

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#gdb #lldb #pwndbg #pwn #ctf #reverseengineering

Paged Out! #8 is out! https://pagedout.institute/ @PagedOut

In "An AWKward Modem" (p. 28), I demonstrate how to write a tiny modem in 5 lines of AWK and shift it into the near-ultrasonic range. πŸ”Š

https://seriot.ch/misc/awkward_modem.mp4

Today in InfoSec Job Security News:

I was looking into an obvious ../.. vulnerability introduced into a major web framework today, and it was committed by username Claude on GitHub. Vibe coded, basically.

So I started looking through Claude commits on GitHub, there’s over 2m of them and it’s about 5% of all open source code this month.

https://github.com/search?q=author%3Aclaude&type=commits&s=author-date&o=desc

As I looked through the code I saw the same class of vulns being introduced over, and over, again - several a minute.

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Just got this link on my discord - https://www.kickstarter.com/projects/bitman/bootblock-rebels - passing it along because this book looks fun!
Bootblock Rebels

The Hidden Stars of the Amiga Underground. Stories from the Amiga Cracking Scene.

Kickstarter
A useful chart on what type to use for flags in C/C++ depending on your D&D alignment:
If you're interested in obscure details of the microcode in the Intel 8087 floating-point chip, I have a new blog post...
https://www.righto.com/2025/12/8087-microcode-conditions.html
Conditions in the Intel 8087 floating-point chip's microcode

In the 1980s, if you wanted your computer to do floating-point calculations faster, you could buy the Intel 8087 floating-point coprocessor ...