#x86 assembler

[whats-in-a-sentence]

In his How To, he lists the skills hackers should acquire first:

Learn C.²²

Learn just a little bit of x86 assembler.²³ You don't have to be great at this at first, but you need to sort of kind of know what the fuck is going on.

Work through Hacking: The Art of Exploitation by Erickson.

Learn JavaScript.

Go through the big exploit archives. Star in the 1990s. Look through exploits. Figure out how they worked. Turn the clock forward to the modern era, so you slowly accustom yourself to newer exploitation techniques.

Get really good at x86 assembler, and learn IDA Pro and OllyDbg.

22. C is a general-purpose, machine-independent programming language that was used to write a range of well-known applications – from Windows operating systems to Oracle databases.

23. x86 assembler is a programming language used for time-sensitive applications and detailed software systems.

"Going Dark: The Secret Social Lives of Extremists" - Julia Ebner

[cyberstudious]

sunday, august 4th, 2024

this weekend I got a library card for the library in my new city and spent a while exploring and getting excited about books. I had to restrain myself from checking out like every book in the tech section because they were all so interesting lol. for now I'm borrowing books on high performance python and identity security, because those are the two topics I'm struggling with at work right now haha. not pictured is Babel, which I'm currently reading as an ebook. I've just been in book mode for the past few weeks and I want to learn all the things!

also yesterday I published a post announcing the studyblr masterpost jam! there's been some chatting around studyblr about bringing back some of the old-style studyblr resource posts and the like, and I thought this would be a fun way to do it! I'll be writing a bunch of masterposts about cybersecurity next week and I'd love to learn about what y'all are studying <3

[assembly-official]

If x86 is so good, why is there no x86_2? Checkmate.

[awizardmostkitty]

had the fun experience of using a debug tool to semi-decompile my own small piece of code so I could figure out what was wrong, the answer is I made a typo, moved to register "cs" instead of "cx" so ofc things didn't work haha

been having fun learning assembly & following a small series on making an operating system :)

[cerulity]

BEHOLD, THE WORLD'S SMALLEST CAT PROGRAM!!!

This is a program that takes in one argument, that being a filename, and prints out the contents of that file. But why is it in a QR code? That's because it's so goddamn tiny. This program is 417 bytes, which is way below the limit of 2953 bytes a QR code can hold. Therefore, I can encode the entire binary file in one QR code.

You can do a surprisingly large amount of stuff in Linux assembly. For one, OS functions are syscalls, meaning you don't need to link to an external library, which completely eliminates symbol tables, link information, and all sorts of other unneeded metadata. The syscalls this program uses are read (to read the file), write (to write to the console), open (to open the file), lseek (to get the file's size), and mmap (to allocate memory).

Not only that, but on Linux, there is an entire /dev/ directory containing pseudo-files that you can open and read/write from to do all sorts of controls and querying. For example, reading from /dev/psaux will return raw PS/2 mouse data which you can parse and interpret.

This was inspired by MattKC's video (https://www.youtube.com/watch?v=ExwqNreocpg) where he made and fit an entire Snake game into a QR code. He had to link to system libraries, so my program isn't directly comparable, but if I can find out how to do linking (i can't use ld because the file is compiled in a raw binary format to get it so tiny) I might do something similar using XLib.

i feel like i should say that you should NOT actually decode and run this as an executable unless you know what you're doing because i have no idea if it'll actually work on your computer or what'll happen if it fails

[7bits]

guys i got 100% on my x86 assembly programming course :DD all that effort paid up

[piratesexmachine420]

There's no hope for computer science. We need to blow it all up and escape into the woods.

[skelleton-bullfrog]

Yayyyyy I'm going to my partners house today! I can show him my assembly program that doesnt fuckign work :3

[neuro-sys]

Variations of roughly 40 bytes of x86 code drawing into mode 13h video buffer.

[horsescary]

match/case is just if/elif with less steps. it should really be cmp/jeq

A non-binary robot with if/then pronouns. Is this anything

[ppyopulii]

if I have to write one more line of assembly ever again

[crowleystolemyshoes]

computer people I'm curious what's your favorite languages to work with. especially assembly languages

[portyanki]

what’s yalls favorite x86-64 instruction?

Extensions count as well

Mine is RDSEED

[sway-official]

You could actually obfuscate assembly code by exploiting the fact that certain (x86) assembly instructions, such as mov, are Turing complete! Therefore the asm code you write could be, if you used this stuff, not the code that people could see on their machine. I've included links to a tool that do this to c code (which has a great presentation linked at the bottom) and the original paper containing this idea ^^

if you write all your code in asm then its guaranteed to be open source

- @sed-official

Chris Sawyer liked that.

[foone]

Growing up in a family with a couple autistic hyperfocusers and a bunch of avid readers and one Normal Guy and then a (now-adult) baby sister with a major learning disability has completely ruined my ability to have any idea what "an average person" knows about.

Like, we've got one person who hasn't even seen a single minute of the Lord of the Rings films, and another has a degree in English literature and did an entire semester on the works of Tolkien. Which one of these peoples is more "normal"? I have no idea!

Or that post of classics puns from Twitter:

How many of these jokes does the average person get? Do they understand Icarus and Medusa but not Orpheus and the joke about "Nobody"?

Anyway it's sometimes a problem because I can (and will!) explain anything at the drop of a hat, but I often am unsure about where to stop.

Like I'm trying to explain how you run Doom on Crabs. Do I need to explain how logic gates work? How transistors work? How computers work? Where do I stop talking and leave it unexplained? Because if I don't rein myself in, I will explain the whole stack from top to bottom and we'll be here all day.

And it's one of those cases where there's not an answer, which I feel is a common bind for people on the autism spectrum to be in. So many of these "don't get social cues" type problems are not because we don't know the answer, in the sense of just being ignorant of what it is, it's that the answer is "it depends on the situation".

Like the question of language formality, or swearing. How much should you swear, if any? There isn't an answer, because it depends on the context. How much is acceptable wildly changes from a hangout with friends to a work meeting to a courthouse to a church.

And similarly, "what does the average person know?" cannot be answered singularly. I explain different things more or less depending on if I'm talking on Tumblr or mastodon or a discord server, because of course you would.

I expect Tumblr to know more about trans issues and fandom, and I expect mastodon (at least the corner I hang out in) to know more about x86 assembly and floppy disks.

But even knowing that and having some success at doing it, there's still some tension because it's the kind of question where the answer is something like "I don't know, you'll have to play it by ear and pick up on subtle social clues" and BOY IS THAT NOT A TYPE OF SITUATION I'M GOOD AT!

[cerulity]

"assembly is a very serious language"

the squirt piss instruction: https://www.felixcloutier.com/x86/sqrtps

the clits instruction: https://www.felixcloutier.com/x86/clts

the fist instruction: https://www.felixcloutier.com/x86/fist:fistp

the move sex instruction: https://www.felixcloutier.com/x86/movsx:movsxd