Google CTF - BEGINNER Reverse Engineering w/ ANGR 

Often the best way for the student to learn is when the teacher is learning too.

John Hammond,TheCyberMentor,Hackersploit,ippsec. Beginner community is in love with u guys❤️

This is way better than reading a writeup

Most youtubers within the first 30 seconds of their videos = begging for likes and subs, John being genuine and honest "I couldn't do it and I had to look at the write up". I seriously appreciate people like you who are open and despite the fact that you've been doing this for 5+ years you are still learning and encouraging people to keep going by doing so. I realise this is an old video but I hope you know it still has a positive impact on people who are looking to get into this and start their journey into the complex world of security.

DUDE JUST KEEEEEEP GOING ! best cybersec channel seriously, freaking love watching you do a CTF, i personally learned a lot from you, thanks a lot !

This is awesome John. Loving seeing the learning process, that in itself is so helpful.

"Solved this with anger" probably describes most debugging/reverse engineering successes

Recent subscriber but I wanted to just compliment you on how well you talk us through your videos and what it is you're actually up to! As a beginner, in almost every possible avenue, understanding is quite difficult sometimes without going away and doing my own research. Sometimes a 10 minute video turns into an hour with me trying to understand things. However, I came across your channel recently and wow. The way you break it down makes it so simple, so I don't necessarily need to understand all the syntax when you explain what its doing so well! Just a little thank you from you to me, you're definitely aiding my learning and re-motivating me to believe I can actually do this lol

Thank you for all the work you do and uploading this AWESOME content!!

Also I love your wrap up summaries that summarize everything and just hammer the whole thing home. Thank you

im really enjoying this. keep it coming John! I have been watching and learning from you since your powershell series updates and the originals you first put out. 👊

I appreciate your transparency John! Everyone in this space is awkwardly trying to learn. Its nice to see that everyone doesn't just start at knowing it all. Practice still makes perfect.

It feels like you underestimate the experience we go through while watching this:) It was cool, thanks for the video!

Please keep making more videos love what you do and love to learn from you. Thank you so much John.

You make great videos. I hope you never stop making them.

This is so helpful John. I appreciate you very much my man. Keep it up

I love your videos!!! It helps me to understand better ways to think through things

Love the step-by-step with thoughts and why!

That’s a nice video, interesting to see something challenging while learning. Good job at presenting!

Hey John, thank you so much, this is really informative and helpful. I like all your videos, and I learn alot from you.

This man hanged out with liveoverflow during the google ctf..... You're so lucky :)

Though this video is a little old now, I want to highlight that seeing and understanding your learning *PROCESS* is just as valuable, if not more so, than learning directly from you like usual. Though, while still very important, understanding how someone may undergo their learning process differently from you can be extremely beneficial! Great stuff as always John, cheers!

Thanks for sharing angr with us! Very insightful.

I like you showing the actual magic behind the curtains. please do more of these they are very benefial

So educative.He makes hard things look easy. Your awesome John

As a newbie to cyber security and Ctfs, I really enjoyed this video. Thanks John!

So rad. Dude you're awesome. Thanks for learning like most of us do and being brave enough to do do it on camera. Using angr in anger.

So I'm new. Like I've got some IT experience but only in the last year have I really started my cybersecurity learning. And in the last month started doing ANYTHING with CTFs. And as discouraging as it is for me having to look things up, you being transparent about it is just encouraging. Thank you.

John I actually find watching you work through a problem you don’t know very very helpful. As a beginner It gives me an example of how to teach myself...? Does this make sense? Any way thank you my guy!

This was very helpful. I need to learn more about reverse engineering myself

Thanks, I am learning something new each video...

This was super clear! Thanks so much!

These videos are so great. Knowing how to code would probably make them even better 😂

Great video as always 👍

I love to watch u trying new methods to achieve the goal.

Love this I hope you keep putting the Google ctf solutions out.

loved it! premium stuff! thanks a lot!

Blessings to you John

Always inspiring 🔥

wowww!!!!!! bro .. I really learnt a lot with you in this video. you are amazingggg mannn

Great video, great value :)

As you said the best way to learn things are to learn from writeups. awesome channel this is.

Liked it. Thanks for showcasing this one. It was the problem I spent most time on and couldn't beat it. This technique will go away in the vault for next time.

You learning on the go, is far from boring - I work now almost 12 years in the field (not ethical Hacking or the sort) however, it is good to see and learn from other how to navigate and lern. I try to get my feet wet with CTF's - Ethical Hacking - Pen-Testing and your videos are so motivating, you boil it down to the essence, never stop learning never stop poking and get your hands dirty! Learn from others and especially from your own mistakes!!! Love the content you put out there! It's so valuable!!!

This was fun! Thank you :)

ur a beast i love these videos

Great video, angr looks really cool!

Loved this.

This was very helpful!

Juicy work done...

Gotta love the honesty. A lot of this low level binex stuff can shatter your self esteem when all you see is just the wins everywhere. It's good to see someone showing the learning process too

its really best to learn it this way thanks for this

John, your walkthroughs are really good. 🧐

I think that having you walk though the learning experience is sometimes more beneficial than just a simple guide/walkthrough. It is definitely more in line with how things play out in reality; research and digging into documentation you are no familiar with.

just got this video recommended, read the name of the channel and thought for almost 10 minutes that if the creator of jurassic park is still alive and has opened a yt channel

Thank you for the videos. You're an excellent teacher. I'm learning so much from you. I agree the way angr found the solution so quickly is some "dark magic". I'm also wondering what practical use cases such a tool might have.

I'm reminded of SoftICE with this back in the day, and thank you for going through the process of obtaining the key - which was arguably the point - but, to save time in practice, I would have just changed the instruction from a JE (Jump Equal), to a JNE (Jump Not Equal), bypassing that branch entirely for every value but the originally-intended one, although that's admittedly not the point, and the process for obtaining the key is extremely informative, so thank you for putting it together. Brute-forcing is of course another approach too.

Thanks! I'm a seasoned dev and never used ltrace thanks I learned something!

When you said, "Most of em solve this with Angr". I felt that

Wow...! I'm returning to programming after... uhm.... forever being away. This is really cool and helpful to look at what is available for tools, how to use and how to sleuth... impressive!

Nice Video :) thanks

That is the only challange that I have ever solved, both during competition and after it And personally did it entirely by hand after checking what THREE assembly instructions which ghidra is decompiling as that mess are doing At least I have learned that x86_64 architecture has some 128 bit registers :D

Shoot from the hip my friend. It’s much more encouraging for beginners than breezily solving it with an air of feigned competence 😎

"i found most people were solving this through anger" always been the standard process at this house. lol

So above my head

- they are trying to solve it with anger. me: ohh, im familiar with that! - ANGR - ohh

Man idgaf if you're reading a writeup you still managed to make the video interesting and we all learned together. I like that you didn't copy and paste. Is a better experience imo than only one of us learning lol. Keep up the good work!

Hi John, i'm searching for a guide of what to use when regarding the sysinternals suite. Thanks for all your work you put in this and beeing a guidepost for the community.

amazing!

Liked it!

Awesome!

I tried as my first challenge in googleCTF as it has least points hours later end up banging my head understanding complicated register play , later reading how people doing with angr automatically solving easily genius man and later more banging my head, i cant solve this 50pts.

Great video. Thank you. When you said you will use angr I thought you meant anger. lol

Really love how these google CTFs writeups are going. It is one thing to watch the videos where the answer is given straight forward but it's another seeing the thought process of John and really going through the steps that i will go through during a CTF and hitting road blocks! Really enjoyed it!

Great video man. You have plenty of skill yourself so don't need to worry that video will be boring :)

Nice video. Besides the learning opportunity, what's the benefit of using angr over a regular brute force script in this case?

From the documentation: factory - "It is not a factory in the java sense, it is merely a home for all the functions that produce new instances of important angr classes and should be sitting on Project."

Nice!

POSIX is Portable Operating System Interface. Just in case anyone was wondering.

As a complete, total noob, I'd like to hear you review what you might have done differently after getting a solution. What would you may e have done differently, was there a faster or easier path you could have taken? After the fact did you spot one or more hints or clues or indicators you didn't see until you had the complete picture? What might you have done differently? Please keep these coming!

I have a question, is angr like just bruteforcing all possible input combinations and checking whether the code hits the success memory address for any of them?

I don’t know anything you did - but I loved it. Thank you -

more of that please

I'm learning from like 3 of the professors on Shellphish!

is there a place where I can download this CTF?

Thanks for the video loved the way you explain things . I have a doubt , can't we just decode the string its comparing the input to?😅

3 years ago hmm good one ❤

Angr is pretty cool, i like the idea of binary r/e being done with ai.

"good, let that angr flow through you"

Hi @John Hammond , is it working with windows binaries too ? PE32+ ?

I have no Idea what is going on,but its awesome!

I love reverse enginering videos

You can also create the whole flag string with `flag = claripy.BVS('flag', 8*FLAGLEN)` and you can add constraings with `state.add_constraints(f >= ord('!'))` etc... "unicorn", based on my research, is when you're running on the same architecture and OS as the binary. It's supposed to make the loading faster. I've just started playing around with angr with crackmes based on these writeups and I've found that it's really hit-or-miss. I can't get it to work with certain strategies. Sometimes an `.explore()` works and sometimes it fails but a `.run()` works which shouldn't be the case... I tried to do it in the "analyze" way where I tried to reverse the pshufb too.. That sucked. It's difficult for me to understand the ASM instructions especially when they're in the newer instruction sets

37:53 i love it, no shame when learning, otherwise we would be cave pepole.

Love this. Just so you know , you're pronouncing it Claripy, but it's actually pronounced Claripy. 🤪

when I'm researching some techniques in coding, I just use a lot of print()'s and just try and see what it gives, like every couple of new lines and ideas, like when you're trying to explain us what it is putting in "flag" and "flag_chars". Why not just print it ? Then we will directly see what it looks like. I can't grasp why people want to write the whole program first and only see results at the very end.

Hey John, what about Hackthebox BombsLanded reverse engineer CTF? Can you show case it?

I just had a look myself. My idea to ignore the strncmp didn’t work because they didn’t print the flag when success only the work SUCCESS. So how I did it was to create a strncmp shared library function, that I preloaded and it would catch the two strings and write them to a file. So I had the string against which was compared - couldn’t get gdb to hand it to me 😂 And then I took the shuffle add and xor constants and basically did the reverse xor again, sub32 instead of add and the shuffle is nasty, that can’t be undone. So I had a look on google (I never used that instruction, didn’t even know it existed) how it goes about mangling. Because I didn’t feel like trying out 15 factorial combinations. And basically wrote the reverse of that too. But it this is “beginner” then I don’t wanna know what advanced is like 😂

If it found "CTF{\x00"... as an output before constraining it, does that mean it would have also been a valid answer (assuming the newline was missing)? I.e. at the command line version, enter: CTF{^D (^D = Press Ctrl-D for EOF). Of course, having to provide it via a webpage breaks that option, since presumable it will always include the newline to input, even though no explicit newline was submitted.

Very nice explanation! Is anyone facing an issue while running the code on their local machine? For me, when I only allow printable characters, then I am not getting any solution. If comment out those lines, I get garbage values as shown in the video. Please help