reverse engineering makes you a better programmer (let’s try it out)

Learning about how computers work through learning a lower level language like C, Rust or Assembly will make you a better programmer, regardless of what language you code in.
One of the best ways to learn about how computers work is through playing capture the flag. In this video, we'll walk through an easy capture the flag challenge where we take apart some ARM code.
Go play CTF at picoctf.org
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[@LowLevelLearning]

Come learn ARM assembly at lowlevel.academy (use code ARMASSEMBLY20 for 20% off lifetime access). or dont. i'm not a cop.

[@gabef9538]

Or just look up the instruction set and read it

[@karaiwulf]

Hey I wanted to know if the videos on LowLevelAcademy were available for download/offline viewing? I want to sign up, but my internet bandwidth's highest speed can be measured in kilobits per second. So almost all of my KZbin/video process is go into town, grab a data dump, and come home to watch.

[@ishansharma4692]

sir can you guide me from where I should start learning about reverse engineering right now I only known basic c/c++

[@erictrinque6513]

got lifetime access a while back, finishing up BootDev right now and cant wait to dive deeper on LLL. thanks as always for the content bud. Superb

[@rajeshpoddar5763]

meaow

[@umikaliprivate]

I wanted to learn assembly for a long time. you should make a whole series about gcc assembly.

[@Redditard]

Agreed

[@RedstonekPL]

for an assembler i very much recommend fasm its simple fast and lightweight it has macros and helper function and has been developed for like 25 years if not longer

[@umikaliprivate]

@@RedstonekPL you know some time ago I actually learned nasm assembly, and made my own framework, which made it easier to manage memory and such. I gave up on it almost immediately, so it didn't go much further than a basic concept and a quick and dirty implementation.

[@renax187]

Agreed

[@viktorhugo1715]

For sure, making a frontend for GCC assembler would be so damn cool xD

[@joshman1019]

Unlike a lot of other KZbinrs, You actually know what you're doing and have a passion for it. One of my favorite tech channels on the platform.

[@halano]

You are not real developer until you recording yourself do some coding.

[@ficolas2]

​@@halanonot at all

[@flflflflflfl]

​​@@halano so Dennis Richie, Ken Tompson, Richard Stallman and Linus Torvalds are not real developers? Got it, thanks!

[@Proferk]

Only sad thing is he likes clickbait :(

[@AntonioZL]

My suggestion for learning low level stuff (and, in some sort, assembly) is to play Zachtronics' games, especially TIS-100, Shenzhen I/O and Exapunks. Although you won't learn a specific set of instructions, given each game uses it's own assembly language for ficticious architectures, you will learn how it is like to use assembly, by dealing with registers, memory, circuit design, CPU cycles, control flow, etc. Besides, you'll have lots of fun!

[@user-io4sr7vg1v]

Thank you for the thoughtful suggestion.

[@AntonioZL]

@@user-io4sr7vg1v Exapunks has a special place in my heart, given I'm a fan of retrofuturism/sci-fi/cyberpunk literature, but TIS-100, with it's 80's charm, and Shenzhen I/O, in it's setting, are also really great! What I like the most about their games is how they're narrative-driven: it's not LeetCode, i.e, coding for the sake of it; but programming puzzles you're personally invested in due to how they're presented and how the narrative is set up. They're really great games!

[@SimonBuchanNz]

The main issue here is Zach's games have (deliberately) awful architectures, extremely limited and quirky. This leads to interesting gameplay, because you can't just reuse a solution you figured out earlier, but it also makes it seem way harder than it actually is on real machines.

[@Zeni-th.]

How is that a problem lol​@@SimonBuchanNz

[@SimonBuchanNz]

@@Zeni-th. mostly that it's pretty easy to be discouraged by thinking that "I'm not smart enough for assembly" Normally the game version of a thing is simpler and easier, but I think that's inverted in this case. Real assembly problems don't come with unit tests, but otherwise they're often easier than an equivalent in Zachtronics games. (Though of course this is very subjective)

[@mlgchuck3145]

This man is a wizard at CS. This dude is my inspiration. So glad I found his channel.

[@dedsec4002]

We need Intel x86 course on the low level academy platform

[@markojojic6223]

No make it RISC-V to prevent recycling code for example

[@arnabbiswasalsodeep]

I've had that in college twice & they made us program the x86 ones using the original way they were programmed, that being use another x86 board with a flashing/burning software connected to addresses gen chip & external storage, where you type in the instructions using a ps/2 keyboard in assembly that you had to manually write it down first and mistake meant waiting to finish then overwrite that particular memory address. All of that just to get led blinking or it posting "hello world" on 2x16 lcd display after 2 hours of pain. Ahh, those were the days. I hated when thry did the same for arm assembly too, but i just used Internet to write it as assignment & through credibility amongst teachers was able to lie about having finished it quickly.

[@AndrewTSq]

we learned asm on 486 back in school. But back then we wrote directly to memory, like the graphics ram etc :) so would be fun to learn how to do it today. but I prefered asm on the Motorla 68k cpus.

[@mudi2000a]

Today everything is so complicated. Back in the day I learned it on the C64 where it was actually easy. When I switched to PC I fiddled a bit with assembly but the abandoned it for Turbo Pascal which was both easy to write as well as performant. Plus if you really wanted you could use inline assembly.

[@markojojic6223]

@@mudi2000a To me this still seems like haven to what my visions of learning that in the future. Lets hope I am juvenoic

[@Little-bird-told-me]

You are reason why I learn C and I am glad I got into low level programming

[@Margen67]

birb

[@ziphy_6471]

Me who can't even code properly in c++ : "Yup, assembly is the right choice for me"

[@rethardotv5874]

C++ is one of the worst programming languages. It’s a minefield of ineffective specialized functions and keywords. Slow polymorphism and weird multiple standard libraries. You either go performant, unsafe and with more code using C, or with lower performance, low code in python. C++ is the weird inbetween.

[@ziphy_6471]

@@rethardotv5874 I'm a openGL dev so I kinda have to use c or c++

[@shauas4224]

​@@rethardotv5874 or go all in and use c#. Using c# after a year of c++ was probably the nicest feeling ever

[@angelcaru]

Tbf C++ is probably harder than ASM

[@ziphy_6471]

@@angelcaru I learned c++ in 1 week

[@sharokhkeshawarz2122]

I get it now, because in my college every single projects are ALL with the exception of none made with C in first year of college. We code 24h/7 in C. In seconde year we do C++ and Assembly and its only in third fourth and fifth year that we do high level languages like python, javascript, java etc...

[@stopcensoringmen5044]

More of these please. We appreciate videos that show and explain how.

[@FUTFFF749]

been looking for this for a long time cant wait for the full series

[@anuragmore4573]

I was just doing the same ctf question yesterday and got headache reading and understanding assembly code again that I've read in my second year at the college. This time I understood it. Thanks.

[@neviswarren]

Great video and information. Thank you.

[@XYZ56771]

i've started picoCTF based on your video, best time invested ever!

[@kermitputermit1437]

love your videos!

[@EngineerNick]

That was amazing thankyou :)

[@dervolker]

couldn‘t have said it any better. reverse engineering got me deep into software development, because i wanted to understand what was going on under the hood. Nothing else makes you understand race conditions like injecting code into another process and randomly crashing, while other times having a perfectly running program.

[@BobChess]

This is a very useful video. I really learn along the way.

[@SharuxD]

bro it just dropped a minute ago, cut the cap

[@ArtemYakovlev]

Thanks for picoGym recommendations. Do more like this one

[@gabirican4813]

Thanks!

[@bharatjeevan]

Dude the way you explain things feels very organic and coherent, even though I don't even know half of what you're saying- I wish I could :) I just started learning a little bit of JavaScript but at the same can't help but feel fascinated by low level programming. Someday, I'll have enough knowledge to be able to understand and appreciate the things you describe in your videos 🙏

[@gabrielmachado5708]

Really great video

[@SanketLakhera]

Thank you, subbed

[@Josip-qu4gb]

When I watch your content I really get motivated. You're helpful and smart, a rare combination 😊 Would have praised you more but gotta go coding🎉

[@k7iq]

Awesome channel ! Been forwarding and reversing bits for quite a while now but I don't know half of what I need to learn... Or something like that. Some day, some where I would love to see a C instructional on more advanced compiler errors and warnings. Beyond the usual missing semi-colon. There may be one of these on this channel even already. Will look

[@sajeucettefoistunevaspasme]

brother, you are the one

[@brandonlai9388]

This is so so true mate, I'm a self-taught student and I get overwhelmed by all the different tools and language, but after I learn about C++, I start to understand what is happening

[@bytesizedfeed]

The only stuff I remember from writing basic assembly is registers (RAX RBX RDX etc) And their use to store information

[@eee-ue7vf]

Appreciate your channel my d00d

[@CasimiroBukayo]

I'm so inspired right now I wanna port the whole Vulkan SDK to Assembly then to pure Machine code, then down to the logic gate 1s and 0s 😅

[@gabrielbarrantes6946]

Any decent CS program would include a course using assembly, C/C++... Those people asking are definitely from an 8hours online JavaScript/python course

[@TDG361]

Great video! It reminds me when I designed a small cpu with vhdl!

[@iamAK47]

Could you do a tutorial on static analysis, this is useful if working on embedded projects

[@user-rr5fm6hg4g]

Khud se kuch karle bhai, bhik mangne ka adat chodde

[@kcnl2522]

Id also love to see reverse engineering of embedded systems.

[@mrlinusmeow]

love it.

[@dhc612]

You should consider having an option on your site to purchase access to individual courses! I'm sure I'm not the only one who thinks buying lifetime access is a bit too much of a financial commitment, especially when I don't know if I'll ever have time for any other courses. Love your videos!

[@diegoj4382]

The best way to learn assembly, is to learn microcontrollers and turn a LED in a protoboard. The best way to be a programmer is to know how your bits a flowing.

[@PauldeBisse-dc8bv]

Something i really like about this kind of video is that there is no cringe music in the background that sometimes can get on top of your voice ; No, there is just you, talking fluently about a really interesting concept. As a french who tries to learn computer science AND english at the same time, thank you.

[@morton4]

this was great

[@Lampe2020]

I watch Ben Eater's videos about his breadboard computer, so I actually have seen quite some assembly before, but assembly meant to run on raw hardware without any OS. So he had to implement the serial print function etc. all by himself.

[@king09426]

That was his own version of assembly.

[@Lampe2020]

@@king09426 But it's still assembly. And it isn't his own, it's 65C02 assembly.

[@lg7t]

AMAZING

[@varshneydevansh]

I was watching your previous video on reverse engineering

[@sauce322aigre]

I needed a video like this 👍

[@JanSoltan-wj1hs]

My first experience with reverse-engineering was decompiling in Ghidra a mobile phone's (SoC Mediatek MT6765, Model OPPO A12) bootloader "Little Kernel" to patch it and basically disable Android Verified Boot. Now when I'm reversing a normal ELF binary I feel like I'm on easy mode

[@brunothedev]

As someone who has dealt with hacking mediatek phones, i feel you

[@hawkbirdtree3660]

I heard that everything is open source when you know assembly 😂

[@kipchickensout]

I think he has a shirt that says that

[@PatrioticGestalt]

My journey was through Commodore 64's 6510 (a varient 6502), Sinclair's Z80, and IBM PC's 8088 (using TASM, then MASM). My $0.02 for learning assembly is to go through VICE (Commodore 64 emulator) and/or a Sinclair emulator. Their design philosophies are very interesting.

[@k98killer]

I made a byte code stack machine in Python. Wheb you run the byte code, it is interpreted by a virtual runtime implemented in Python, which itself is compiled to byte code and runs in a virtual machine.

[@Becoming-Human]

Excellent video! Thank you! Are there any considerations for showing a similar video, but focused on RISC-V? Thank you, again, and I look forward to more videos like this. :-)

[@wcrb15]

This was so very clearly articulated. I appreciate the thorough walk through!

[@geoffreykioi3272]

I just realised that I've always been a nerd. And I love it

[@logiciananimal]

For those who can afford (and could make use of - some people don't like them) a textbook, CMU is also home (so to say) to _Computer Systems: A Programmer’s Perspective_. (Disclaimer: I took the course this is used in - or a version thereof - 20+ years ago while a student there in Logic and Computation.) I do echo our host's recommendation of CTFs for the subject - the text might be useful as a reference.

[@luismuller6505]

Damn that was a smooth intro.

[@randomguy2447]

Not gonna say too much on here but my CO recognized you when I was watching your video while working on the JQR for basic tool dev lol

[@xylh5085]

I would be interested in a video about learning the systems that the assembly interfaces with and how you would, for example, learn x86_64 assembly calling conventions, syscalls, stack frame setups, etc. Also, my terminology might be off, so apologies if my question isn't intelligible

[@a.v7998]

I always wanted to learn assembly, And so far i have only managed to learn very basics. Im still trying to learn assembly by reading assembly code and dunping C binaries to assembly!

[@TrippleXD545]

it goes the other way too with knowing the high level stuff (ie design patterns) :3

[@MorgurEdits]

That was wild hearing your spell atoi the first time. I spell it completely differently :D

[@ewhac]

9:59: ERROR: INVALID MNEMONIC INTERPRETATION DETAILS: `BLS` is "Branch if Lower or Same," which is _distinct_ from Branch if Less Than (`BLT`). BLS is used to compare unsigned integers; BLT gets used with signed integers. I always had difficulty conceptualizing the compare (`CMP`) operation, until I finally realized: `CMP` is identical to `SUB` (Subtract), except that it throws the result away and keeps the flags. So `CMP w1, w0` can be thought of as `SUB w1, w0` (i.e. result = w1 - w0) and thinking about the result of that subtraction. Is the signed result Less Than zero? If so, `BLT` is what you want. For unsigned integers, is the result underflowed (Lower) or equal to zero (Same)? If so, `BLS` is what you want.

[@Ma1ne2]

This was really fun and informative, I felt like watching Sherlock Holmes!

[@thedrunkmonkshow]

I've never seen Arm Assembly or had it explained to me before so it was revealing to see that fundamentally, while it has it's own unique ISA, it pretty much does the same tasks that you would find in older chips like the 6502, Z80, x86, or 68000k. For some reason I assumed since CPUs have way more registers now it would be too complex to grasp but surprisingly nope, still the same building block process of moving values to and from CPU, to and from Memory, and to and from the Stack. 😃

[@starlightfury4252]

great timing. i am heading into summer (with no internship :( ) and i thought of picking up reverse engineering. what do you think about utilizing books for learning rev eng?

[@justsomeone7391]

Personally, the most education I've learned from low-level stuff was from OS development.

[@user-jz2xp9pp6w]

Pity that the code had a BLS instruction, not BLE - this would have made a good case for showing how signed numbers are encoded in binary and how the seemingly smaller number in the example would have turned out to be the larger one

[@Im_Ninooo]

yesterday I learned about ImHex and ended up reverse-engineering game save files for fun till 2am 😆 it's so cool

[@ErazerPT]

Oh nice... Thanks for that one, didn't know about it. I'm used to just having having the hex ed, a text ed for notes and writing a "reader" as i go, but having some "integrated all in one" software for it sure would save time...

[@Im_Ninooo]

@@ErazerPT yep, their pattern language is really powerful

[@Cyclically]

Just grind crackmes even just once a week, I used to do those endlessly for years back when I was 13.

[@healxt5427]

I would like a Risc v assemply playlist from u

[@NoiecityHacking]

ASM for write shaders in pixel shader and vertex shader i think, and understand GLSL and HLSL, like Blender or Unreal engine

[@JohnDoe-np7do]

Lol i had this crazy idea ab reverse engineering passwd. My logic was that if it were written in C, then at the point where stdin is opened an youre promted to input a password, there should be a strcmp() between the inputted pw & the current users "stored password", in which case 1 out of 2 branches are taken, where the password is a match and where its not. Tried using objdump to dump the disassembly of the binary & see if i could try to find the cmp instruction, fast forward to numerous grep results of cmp & je instructions, i encountered a skill issue real quick. Decided that if im actually gonna do it, to use ghidra instead coz im hopless at asm 😂

[@mehdiboujid8761]

what s the font used in the terminal ? love your content

[@rudiger86]

I want to learn assembly but I don’t know where to get started

[@jamesking2439]

I got started with low level programming by making small cheats and mods in Cheat Engine.

[@Andile-jz1vs]

seems like, Iam the only one who does not understand s***

[@oalmaftool]

You will If you search the meaning of terms you don’t understand. Keep it up

[@CalmCabezonFish-nb6qt]

Bro, then I'm better than you

[@tiagocerqueira9459]

For me, in university learning the fundamentals of programming and then data structures all in C was 90% of the way

[@systemhalodark]

There is also the legend of R4ndom, even if it is pretty old by now.

[@SmashingJonor]

The lower level languages might seem hard and assembly language sure is hard, but at the same time the complexity level in the language tends to not be very high. It's true that C++ compilation errors can be some of the biggest headaches a human will ever experience in life, but I feel the language itself is very straight forward as opposed to C# WPF with it's unholy XAML--C# hybrid language.

[@AutoDisheep]

I am new to programming, but with a bg in maths

[@user-ox4ii2bw6x]

THIS MAKES LIKE SO MUCH MORE SENSE HOLY SHIT MAYBE IM NOT COOKED

[@SWAGCOWVIDEO]

I tried getting into reverse engineering to get an old program made for Windows XP to work better through Wine on Linux. I'm a novice when it comes to assembly and only have trace amounts of computing principles from college. There was such an insane amount of information that I wasn't used to and I could only occasionally get a glimpse of what was going on under the hood. I'd have better luck trying to read a foreign language with no translator. Wonder if doing small challenges like the one you're showing help to remove the obfuscation.

[@shivamchauhan19]

Quick question: Isn't BLS 'branch if lower or same' rather than 'branch if less than'? So it would be used for conditions where argv[1]

[@berndeckenfels]

Should have mentioned „calling convention“

[@Kane0123]

I’m willing bet 14mins of my time. Let’s go.

[@remiheneault8208]

I have the privilege of knowing a low-level and a high-level language... The perfect synergy to hate both. One is either slow or an expensive wrapper for C functions underneath. The other is very fast yet every millisecond using it feels like a lifetime. I remember... I remember when _sudo_ was a synonym of power, when XML-RPC was the future for data, when machine-learning and logic each had their role, when WebAssembly promised to bring harmony to us all... My reference to hope has long been freed but sorrow keeps leaking. Should I hang up, give the final signal? I hear my soul - kernel of my being - panicking: *"No !"* When stuck in that eternal recursion, when linkers scream in a long-forgotten dialect, when heap and stack overflow... I tell myself: "At least I don't code in JS."

[@adagioleopard6415]

I think this is why so many software companies poach hardware/firmware developers so often

[@MsHojat]

I imagine that before you do these you'd still need to first learn some of the basics of assembly though.

[@simplexination9837]

Best way to learn programming is learn to read code base asap and get the idea behind.

[@plutoniumoxide467]

For anyone wanting to learn computer architecture, the Elements of Computing Systems book is a great one, takes you all the way from what is a 16 bit adder, to a high level language that runs on a cpu you built.

[@Zeni-th.]

Do u have a pdf for it?

[@ashyy6819]

@@Zeni-th. f.javier.io/rep/books/The%20Elements%20of%20Computing%20Systems(dot)pdf

[@future_teknokrat7585]

Reverse engineering is how I learn most anything if it's possible.

[@thefanboy3285]

Do you have an official documentation on x86 assembly to advise from which I can learn assembly ?

[@abelthomas8232]

Do you have an arm processor? normally you cant run arm binaries on intel based processors right? or are you using some virtualization?

[@ontley]

What font do you use?

[@j.ysr0]

FONT NAME?

[@sanjaycse9608]

Oo its the third title😂

[@tarzanzabujca]

what am i missing, why is the first number greather than second one

[@user-rw5zp2tl5l]

Only binary reverse engineering? Is there no reverse engineering of webpage JavaScript source code? For example, cookies are encrypted. Find the location of the encryption function in the source code.

[@luis_mz08]

not gonna lie, i’m kind of annoyed by the fact that there’s multiple kinds of assembly syntax like a know quite a bit of x86 64bit nasm assembly but the arm assembly syntax is so different that I don’t know any instructions apart from like mov and add

[@vectoralphaSec]

That's one reason assembly is hard. There are a lot and they are all different and specific to each cpu architecture.

[@djh1455]

Thanks for the videos, Ed! I have some intro assembly and pep8 courses etc but never could get deeper.. Can you recommend any resources for how to build on understanding a decompiled program as a human ie the thousands of instructions for intel x86 there may be in a given program? I would love to learn the bridge between the basic concepts and real world disassembly ie IDA or Gidra.

[@ErazerPT]

The easy way imho is to go at it in the reverse direction. Write small C stuff, like add argv[1] to argv[2] and return the result. Pass argv[1] and argv[2] to a function, return the result of the addition then return the return value. Do some simple loops with no operations. Do same loops doing some basic operations. Use a compiler to output assembly with no optimization. Look at C source and asm source side by side. Once you've done it enough, you'll just see the patterns "emerge". C is a good pick to start, because it will be very close, but anything that can produce asm is ok. If it can't produce asm, still ok, just make the executable and disassemble it. If you focus on recognizing the "basics", you can easily fill in any parts you don't know by just looking up what the instruction does.

[@djh1455]

@@ErazerPT Thanks!

[@Muhammed.Abd.]

How was he able to run arm assembly code on hislinux machine?

[@kaporos]

hey ! thanks for the vid ! did you configure something to have arm executables running on your machine ? (you might be arm ahha but is there any way on x86 ?)

[@LowLevelLearning]

sudo apt install qemu-user

[@JonasMielke]

But is it expected to analyze the assembly for this ctf like you did? Couldn't one just compile and test?

[@Sluggernaut]

Do you study instruction sets or what? Seems pretty in depth, more than I expected even, needing to understand ARM architecture in this case.

[@spaghettiking653]

Maybe just use compiler explorer, and you'll be able to figure out what instructions mean what quite quickly.

[@Sluggernaut]

@@spaghettiking653 That doesn't sound right, but I don't know enough about stars to dispute it.

[@spaghettiking653]

@@Sluggernaut Stars? What do you mean?

[@devnarula6733]

do you think someone who is in applications development and not necessarily into security shall also do CTF's? I really like low level assembly and development but I don't know as a Java developer if CTF is beneficial for me