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Gynvael Coldwind

@gynvael.bsky.social

2.7K followers 57 following 70 posts

Security researcher/programmer ⁂ Managing director @ HexArcana ⁂ @DragonSectorCTF founder ⁂ he/him

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Gynvael Coldwind @gynvael.bsky.social · Jul 2

Yet another ZIP trick...
hackarcana.com/article/yet-...

+ a hands on exercise if you want to try this yourself:
hackarcana.com/article/yet-...

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Gynvael Coldwind @gynvael.bsky.social · Sep 9

We've received 50 required articles for issue #7 of
@pagedout.bsky.social - this means we're publishing the issue in the few next weeks.
1. Want to get an article in #7? You should write it now and send it in in the next few days.
2. We're still looking for more issue sponsors!

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Gynvael Coldwind @gynvael.bsky.social · Sep 2

OK, ChatGPT 5 admittedly surprised me in a positive way. I threw a PNG with a (small) Python AST graph at it and told it to reverse it to Python code, and it successfully did that. I have expected it to fail hard, but here we are 🤷.

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Gynvael Coldwind @gynvael.bsky.social · Aug 11

Friendly reminder that order of operations makes a difference... more so than you think ;)

Python: 20000000000000000000.0 + 1337.0 - 20000000000000000000.0 is 0, but same numbers, with addition of 1337 moved after subtraction results in 1337.

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Gynvael Coldwind @gynvael.bsky.social · Jul 10

Lulu (print on demand) is increasing prices by 5% from Aug 1st, so if you were thinking of getting @pagedout.bsky.social #6 there, do it now: www.lulu.com/search?page=...

Shop the Independent Bookstore | Lulu

www.lulu.com

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Gynvael Coldwind @gynvael.bsky.social · Jul 5

[Please share with people outside of cybersec]
Do you have a horror story when you had to deal with cybersecurity companies / people? This is your chance to vent! → forms.gle/9aX24HrfnEQm...
I'm running an anonymous survey to listen to stories and look into the disconnect we sometimes have.

Frustration with cybersecurity people and companies

This anonymous survey if for people who are NOT working in cybersecurity and who had to contract people / buy services / buy products from companies in cybersecurity / use cybersecurity products / etc...

forms.gle

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Gynvael Coldwind @gynvael.bsky.social · Jul 2

Yet another ZIP trick...
hackarcana.com/article/yet-...

+ a hands on exercise if you want to try this yourself:
hackarcana.com/article/yet-...

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Gynvael Coldwind @gynvael.bsky.social · May 23

A (not so) short analysis of anonymization schema used in the "Discord Unveiled" paper: hackarcana.com/article/anon...

Gynvael Coldwind @gynvael.bsky.social · May 18

Thanks! That's MacOS Terminal.app, right?

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Gynvael Coldwind @gynvael.bsky.social · May 16

Poll! What ANSI color types does your terminal support?

"\x1b[1;31m3bpp+attr\x1b[m \x1b[91m4bpp\x1b[m \x1b[38:5:196m8bpp\x1b[m \x1b[38;2;255;0;0m24bpp\x1b[m"

Reply with screenshot of the output of this string + add OS/terminal versions

E.g. Ubuntu 24.04.2LTS, Konsole 23.08.5

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Gynvael Coldwind @gynvael.bsky.social · May 12

Btw, is there sth like (www.web3isgoinggreat.com) but about AI fails?

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Gynvael Coldwind @gynvael.bsky.social · Apr 28

[PL] W przyszłym tygodniu zaczynam nową serię szkoleniową - 10 projektów w Pythonie krok po kroku (python.sekurak.pl). Coś dla osób bardziej początkujących, w szczególności dla osób, które trafiły na ścianę po hello world / kalkulatorze, albo mają problem jak ↓

Gynvael Coldwind @gynvael.bsky.social · Apr 2

Doing a short livestream in ~30 minutes with inspecting a pcap with USB traffic from a gamepad – www.youtube.com/live/xVrxfEk...

🎮 Live CTF: Solving "Gamepad" from Gynvael’s Collection | hackArcana Challenge

YouTube video by GynvaelEN

www.youtube.com

Gynvael Coldwind @gynvael.bsky.social · Mar 31

Doing a free webinar today at 8PM CEST (i.e. livestream with slides) about "files", as entities on the filesystem, seen through the eyes of a security researcher.
hexarcana.ch/lp/files/ ← sign up here if interested

Gynvael Coldwind @gynvael.bsky.social · Mar 29

Paged Out! #6 is out!
pagedout.institute
Totally free, 80 pages, best issue so far!
'nuff said, enjoy!

(please repost to help spread out the news!)

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Gynvael Coldwind @gynvael.bsky.social · Mar 26

Note: This webinar is about files as seen from the perspective of the OS/filesystem/sysadmin, and not about what's INSIDE the files.
hackarcana.com/bin?utm=gyn-b ← This workshop covers what's INSIDE the files :)

Gynvael Coldwind @gynvael.bsky.social · Mar 26

Next Monday I'm doing a 2h webinar on files as seen through the eyes of a cybersecurity researcher. This will cover useful stuff for programmers, more junior pentesters, and other tech enthusiasts who enjoy knowing how stuff works on a computer :)
hexarcana.ch/lp/files/?ut...

Files through the eyes of a hacker

hexarcana.ch

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Gynvael Coldwind @gynvael.bsky.social · Mar 24

I'm getting some specific questions about my upcoming training – I'll update the training page later today. This said, I've also recorded a short show-case / case-study of what type of skill one will acquire on my training:
www.youtube.com/watch?v=ib4Y...

Reversing unknown file download protocol

YouTube video by GynvaelEN

www.youtube.com

Gynvael Coldwind @gynvael.bsky.social · Mar 21

Thank you Paweł for the very kind words – I really appreciate it! :)

Gynvael Coldwind @gynvael.bsky.social · Mar 21

tmp.0ut Volume 4 just came out!!! LET'S GO!
And guess who's article is there ;)

08 .... FixedASLR: .o ELF loader in a CTF task

tmpout.sh/4/

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Gynvael Coldwind @gynvael.bsky.social · Mar 21

I'm running an "Intro to programming and Python" workshop (in Polish) in the evening with Sekurak / securitum and we have over 10 000 people registered. This is definitely and a new record for me!!!

If you understand Polish, you can still sign up at sklep.securitum.pl/wstep-do-pro...

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Gynvael Coldwind @gynvael.bsky.social · Mar 19

A lot of you were telling me I should do my courses in English, so here we go:

Mastering Binary Files and Protocols: The Complete Journey
hackarcana.com/bin?utm=gyn-b

This is an A-to-Z course teaching a fundamental skill in practical IT, useful in cybersec/coding/etc
Start Apr 8th

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Gynvael Coldwind @gynvael.bsky.social · Mar 19

It's been a moment since I've posted sth on my YT channel, so here we go:
www.youtube.com/watch?v=jBsV...
I'm going here through my "pressing CTRL+D is like ENTER pressing" article – enjoy!

Pressing CTRL+D Is NOT what you think!

YouTube video by GynvaelEN

www.youtube.com

Gynvael Coldwind @gynvael.bsky.social · Mar 17

I've written another article, this time on the fundamental reason why we have all these XSSes/SQLIs/etc. At least that's the way I explain it ;)
hackarcana.com/article/why-...

There's also a CTF challenge for this article (misc60):
hackarcana.com/article/why-...

Enjoy!

hackarcana.com

Gynvael Coldwind @gynvael.bsky.social · Mar 14

If you like CTF challenges, we've been steadily pushing some of my favorite tasks to my new edu site:
hackarcana.com/exercises
From top to bottom: Linux RE, 2x JS RE, USB PCAP, ZIP/crypto, DOS/VGA RE, 2x BMP image stegano, 5x BMP file format stegano, Python 2.7 RE, and ROP RE
HFGL

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Gynvael Coldwind @gynvael.bsky.social · Mar 11

based