Debugging An Undebuggable App

[@nodrance]

Doing this much to prevent debugging is like hanging up a giant warning sign saying "I AM BEING SUSPICIOUS"

[@Toad-k7e]

or its anticheat?

[@SeprexOG]

@@Toad-k7eye

[@taktuscat4250]

@@Toad-k7e its not even a game

[@Toad-k7e]

@ no one said it was.

[@Toad-k7e]

@ it could also be DRM to prevent cracking

[@wardyorgason]

now I want to know the conspiracy behind having all of these protections

[@misternachname517]

prob just cracking protection

[@dahahaka]

​@@misternachname517 either that or they're doing something shady

[@Y3ee]

you should check out the app's privacy policy, it's actually so stupid, how much stuff they collect. Them trying to hide from debuggers, jailbroken phones etc. just makes it so much scarier.

[@lbgstzockt8493]

The "conspiracy" is that they spy on you every waking moment and sell the data to anyone who is willing to pay.

[@nmslesecnmbese917]

The UI looks like a typical chinese app, so what's the expectation?

[@henningerhenningstone691]

"Debugging An Undebuggable App" sounds like my day-job, except I wrote the app 😅

[@Joh447]

"what sort of lunatic moron coded this piece of sh- oh... That would be me"

[@kali_chai]

"I love writing code, I love testing code, and I really love developing code" -No CSC/CPE worker ever

[@FancyPotatOS]

The usage of the snapshot call until it crashes is HILARIOUS and feels so ‘junior dev knows a security hack’. Even seeing the ‘while(1)’ is such an indication that something silly is occurring in code

[@NSXPCConnection]

10:37 that someone who found the method by the way is Amelia While, really smart person! She found it in iOS ~13 or 15 I don’t remember but it STILL hasn’t been patched

[@brycedotco]

Ha!! I looked around a bit but could not find the history here - best I could find (after recording/editing) was that TrollLock-Reborn uses this to back its respring functionality. Can't believe it's been around that long. This is awesome, thanks for sharing!

[@ramsey2155]

At that point its just malicious behaviour. That app should not even be allowed to be deployed

[@llsc12dev]

@@brycedotcounfortunately amy’s method stopped working in the developer betas of ios 18. its funny that it took so long for apple to decide to fix lol

[@nono1271]

Name looked suspicious, searched it and just found a white male whom people call something he's not and never will be 😑

[@NoTraceOfSense]

omg my oomf in the wild

[@encodedlife]

Dude that level of mastery in reverse engineering is impressive!

[@ne.uveren]

This is a good example of the main rule of cyber security: doesn't matter how protected you are, if someone really wants to get in, they will find a way. The only question is, how long can you stall them for

[@ДаниилРабинович-б9п]

It's sometimes possible to make things that you run impervious to outside connections, but the moment a thing is running on the client side, you might as well assume the client has full control.

[@ggsap]

this only applies for client side

[@Architector_4]

@@ggsap I mean, theoretically of course, but a determined enough adversary could physically break into your server room and make your server software clientside to them too lol

[@tbuk8350]

This. The most important thing when developing an app (that you want to keep secure), is that you can NEVER trust the client. No amount of signing, checksums, obfuscation, etc. can protect a client-side program from someone who is determined enough. All you can do is slow them down. The only thing you as a developer can ever trust is your own hardware, which is usually the server. Write your networked programs so that the server validates EVERY action, and denies any request from the client that is out of its bounds. Then you leave blindly attacking the server and trying to find vulnerabilities in private code as the only option for the attacker, which is 1000x more difficult than hacking client-side code, which can be debugged, reverse-engineered, etc.

[@tarosykes]

@@Architector_4oh hey architector :)

[@williamkaiser6075]

The streisand effect, but for protecting your app binaries

[@slime_stick]

Just learned a new word 😮

[@noewaeda]

"protecting" your app binaries is already a bad idea to begin with

[@john.dough.]

woah! as someone used to Linux reverse engineering with Ghidra, it's wild how many things are so similar yet so different! thanks for sharing :0

[@tijtij]

Got this video suggested by the algorithm and I am happy I clicked on it. The concepts are explained very clearly. I know very little about assembly but had no trouble following along. Instant subscribe.

[@VerifyBot]

This was such a joy to watch! The way you explain everything calmly and enthusiastically is genuinly so charming Keep up with this!

[@tdrg_]

It’s incredible how I can understand 10% of what you’re doing and still enjoy it so much Thanks for the video!

[@pantherosgaming1995]

That method of torpedo-ing the phone memory can actually be considered malicious.

[@SeizureSalad]

i've never seen reverse engineering explained in such an easy to understand and digest way. I've been trying to teach myself intel x86 assembly and IDA for some time now but still haven't gotten the hang of it and don't know where to start but this was really interesting to watch

[@brycedotco]

It takes awhile - I'm definitely still learning too. Keep at it!

[@flameddogo]

"Feed two birds with one scone" is hilarious

[@jackedakk]

the efficient pacifist

[@lbgstzockt8493]

PETA approved

[@vertexstuff]

I was not ready for that lolll

[@NithinJune]

i’m pretty sure PETA came up with this 😭

[@nuvotion-live]

Much nicer :)

[@ResizePixel]

This is so fun to watch as a much higher level programming language developer. I love seeing these concepts and watching you step through assembly. It makes me want to challenge myself to learn more!

[@lampree]

I think the most impressive part of your videos isn’t even your reverse engineering skills (which are great) but your ability to explain a complex subject and keep anyone interested. That is talent!

[@nagyszabolcs9451]

I don't really have experience with ios specifically, but your explanations make this so watchable, can't wait for part 2!

[@Mabeloid]

i know nothing about this debugging area of programming and i have to let you know how clear and good all your explanations are that nothing went over my head

[@voilin]

I'm not an apple dev, but your presentation was so good I decided to stay anyway, that was masterful!

[@TheOliveOli38]

Ngl blocking debuggers and having jailbreak protection is something I'd expect from stuff like Mario Kart Tour (which does have those protection measures because of anti-cheat, which is also the same reason why it's online-only) but a widget app? Are the devs really that greedy for ad revenue? (Which I'm guessing is the main reason why they did all of that; they don't want people bypassing ads or cracking IAPs)

[@codewithkanishk7500]

Perfectly explained, Person like me who had never written Objective C or never done any IOS development can easily understand how things are working, Thanks man your teaching skills are absolutely phenomenal.

[@_opa334]

But I thought the App Store was secure and Apple manually verifies all submissions to not be malicious??? Was my life a lie??? 😢😢😢 /s

[@qwfp]

There is no malicious apps in the App Store. 😃

[@brycedotco]

this is totally the only one, probably, i swear

[@user-lj4lo7cx7m]

As a developer in a big company here at US: No. They don't verify deeply our app, and it usually takes a few hours to get approved

[@sorae42]

Most of the software storefronts only do deep analysis on the softwares first submission. Later updates are usually quickly skimmed thru so they can get the new version up and running asap.

[@thewhitefalcon8539]

They are verifying their financial security, not your computer security.

[@DarrenJohn10X]

I don't ever code in assembly, and I don't have or use any Apple products. But I watched this entire video. You are excellent at explaining every step. 👏

[@TechX1320]

I cannot stand Root detection/Jailbreak detection. It all started with people thinking "Oh, cheaters root/jailbreak" when you don't even need to. You can mod the app and sideload. On iOS, yes, this is far more difficult than android, but still possible.

[@gnorts_mr_alien]

you are an amazing communicator. think your channel will go very far.

[@yassine-sa]

18:12 God, he's literally about to collapse and start crying 😂😂😂

[@oskarristolang]

absolutely love your videos, they're so complex but yet so simple

[@Flor-ian]

The dedication to recording the video twice is insane. Love the content and happy to see a new upload!

[@rosawatson6813]

Amazing production quality! Absolutely love it. My experience goes as far as "doing random stuff with frida". Learned quite a bit from this.

[@DaxSudo]

This is the most underrated channel I have ever seen and I love it. Everything you’re doing I’m on the exact opposite side of that react native, native development, web development API’s, edge services. Full stack and u hack it I love it so much.

[@abdallaaltaay4487]

Is there a similar channel that does the same thing but android

[@brycedotco]

(watching this thread so that if anybody has any recommendations, I can learn too, ty)

[@bity-bite]

Closest I can think of is LauireWired

[@asdhuman]

also you can apply a lot of this knowledge to android too

[@FaizanAli-visiontech]

​@@brycedotcoMe too

[@reabstraction]

​@@brycedotco There is something called ReVanced if you want to patch apps yourself Its a plugin patcher for Android Most known for patching KZbin It can patch any app Unless it uses Play Integrity API In which case that will need to be patched out using microG as a replacement As Play Integrity API requires code signing

[@alvinjoycharles6914]

My absolute favourite channel on yt. Please keep making this kind of content!!

[@Daniel15au]

I don't own any Apple devices (neither does anyone in my family) and have never written code for iOS, but I still enjoyed this video. Nice work!

[@gFamWeb]

As a security researcher, this video is so incredibly fascinating and also extremely helpful for whenever I need to use `lldb`.

[@Observer552]

Is every app open-source for you? Great video, and I was feeling sad for recording the video twice

[@yassine-sa]

Bro I can't imagine how hard learning all of this must have been, this is so frkn awesomme

[@kwiky5643]

not really given how interesting it is. It's not "basic knowledge", but it's not like it's obscure stuff either if you're an iOS dev

[@yassine-sa]

@kwiky5643 yes I agree, I'm not an IOS dev( I'm not in the apple ecosystem) and i can see what you mean, but still what he did is so cool I wanna try ios dev as soon as i get an apple computer and i have time

[@yandevelop]

Really great video! I'm glad that I found your channel. I'm a tweak developer for jailbreaks myself so this is very interesting to see! Good job :)

[@appelveg]

Very in depth! Love your explanations, you were literally explaining as I was figuring out! And the app is SOOOO sketchy :)

[@rugmj]

Really enjoy seeing your videos, I learn something which helps me write tweaks every time :)

[@bocchertherock]

The single apostrophe after the app name label is just enough to classify this app as suspicious. General rule of thumb: If a program/app name uses non-alphanumeric characters in weird places, that's one red flag.

[@eastarctica513]

This video is actually amazing! It goes over tons of the things I’ve had trouble with when dabbling in iOS reversing. I’ll have to look into those group identifiers a bit more though to learn how they actually work

[@developertpl]

I really enjoy your content and the way you explain complex iOS features. It would be really nice to be able to watch you building an application, either as a series or a live coding session.

[@brycedotco]

I appreciate that! I've never been sure if building a normal thing would be super interesting to people - this gives me some motivation. Thanks!

[@jirehla-ab1671]

​How abt disassembly (viewing assembly code) instead of debugging, would the steps be different? @@brycedotco Same platform IOS

[@ggsap]

@@brycedotco It probably won't but this reverse engineering format is quite intresting!

[@ahmetdenizsezgin]

3:03 No you’re not best sentence i have ever heard this year about coding

[@SimSel02]

I love your videos and you have very impressive skills (I really enjoy how you explain)! Keep it up! I’d also like to see videos published more often

[@nobodyknows-vk3iv]

it's a crime for this video not go viral

[@mikaay4269]

I've never had any apple device and probably never will, but this content is still really interesting. Keep it up!

[@cihadturhan]

Great job man! I love your videos. It's full of information and I still understand it even if I have very limited ios dev experience. Now, when I think about how I can protect my app from hackers, there is literally no way I can think of

[@boomanten1020]

I havent done any iOS reversing, but you have such a good way of explaining things that help me outside of the Apple environment. Also like how iOS manual pages mention the BSD System Call

[@seekyboi23]

Because macOS and iOS are forks of FreeBSD

[@dahahaka]

The snapshot loop is kinda hilarious

[@jondycz]

Now try McDonald's app

[@iskamag]

Jailbreak "protection" is so annoying. It often triggers when jailbreak's inactive too. Just let me use my phone how I want damnit!

[@arjundureja]

Can't wait for the next video. Need to know why this app has so many protections

[@tokero5199]

Great video! I was sure you were going to to patch the bin with a noop or something but setting a break on the mem address was clever.

[@NithinJune]

13:05 oh god if you weren’t sure that you don’t want this app anywhere near your phone, that temu app layout seals the deal

[@TheOnlyASDK]

it reminds me of the OPPO Theme Store, the UI design is very similar

[@NithinJune]

@ i think it’s a chinese design language. if you look at chinese websites and apps, we would probably consider them cluttered and trashy

[@TheOnlyASDK]

@@NithinJune True, they have very information dense design principles

[@VanillaSpooks]

Feed two birds with one scone??? The birds will now battle over the scone

[@dewantawsif]

So I had seen your very first video and after a year KZbin recommends this one. Subscribed so I can get more on my feed.

[@etino]

Your channel is golden. Respect man! Keep it up :)

[@MrRonanX]

This channel is a hidden gem of the iOS Engineering!

[@seansingh4421]

Check for canaries as well. A lot of softwares have reverse engineering/debugging canaries that only activate when you analyze them

[@camillelouedoc3799]

I finally found the perfect KZbin channel for my lunch break 🍻

[@moohric]

Man, this is entertaining to watch during lunch :D

[@thundertastic896]

Dude, you're doing stuff with the debugger that I thought were not possible, would you be down to make a video about common and not so common tricks to debug applications? In this age of printf debugging nobody really praises the abilities of the debugger.

[@Kaleb_Weise]

Thanks for taking us through the journey! 🥂

[@henriquematias1986]

Super cool video dude! What else did you find inside that was suspicious 😂

[@elmigranto]

Extremely well-done and explained. I am beyond impressed! 💯

[@0xbitbybit]

You know someone knows what they're talking about when they can afford/use IDA Pro 😂Awesome video and I haven't even done anything to do with iOS!

[@ItsD3vil]

You are a gem man love your content so much keep it up!

[@pilothyper]

I barely even know how to style text in CSS, so this stuff is a whole new realm for me dang xD

[@joshynoshy]

I NEED to know why. WHYYYY? Why did they make the app so scared of debugger?

[@TheOisannNetwork]

In general: It's about regulation, fraud prevention, anti-cheating and IP protection. I'm sure there are other reasons too, but those are for sure the main ones.

[@LetrixAR]

The app has in-app purchases

[@IrtyGo560]

1) this app is chinese 2) money can change hands in this app

[@lekeshala3735]

I really enjoyed this video, showed me how much I didn't know about reverse engineering, good job.

[@LeonOF-i3f]

bro is the goat we all needed

[@TimTheBeastNL]

love the vids, would love to see a more detailed video or blog about FLEX. Would be cool to fully understand how to install and use it.

[@NerdOfComputers]

this mustve take long to edit but worth it!

[@snowyy304]

You're a legend, my dude! Your reverse engineering is impressive as hell 🔥🔥🔥

[@asandax6]

It seems if you make an app harder to crack Hackers just get motivated to crack it even more.

[@lukasjetu9776]

I like how the word 'ptrace' in the captions is more and more b`ro`ke`n

[@lukasjetu9776]

nevermind, ignore this

[@jannikheidemann3805]

Peat race

[@danmorgan712]

As someone that loathes Apple and avoids their products like the plague, I still found this to just be an interesting video and found myself watching the entire thing and wanting more. Nice presentation.

[@worldgeektube]

First class. Great analysis. No fluff.

[@RobertNMusic]

Love the video and great explanation! Would like to have more horizontal space on your windows though 😬 Could have XCode or disassembler top of screen and terminal bottom so that both get more width

[@Visitor______________________v]

So much skill here, very interesting

[@APerson-14]

gotta love apple allowing malaware yet can't allow 3rd party app stores

[@nirusplex]

Its a piece of art. Loved it.

[@distortions]

This is a cool series.

[@Alcaline-hu2vu]

They say everything is open source if you know assembly

[@JZL003]

I just enjoy watching this, but there's so many helpful tips! I know it's maybe between 'purely educational' and 'live coding' but I think collating some of your tips into the description could be a nice summary for people who were actually learning and going to use

[@MarioMakesSftwr]

amazing content as always!

[@BitZorg]

I haven't tried this, but I'm pretty sure ghidra can connect to a LLDB server and you can debug it that way. Might be nice for ant longer debugging sessions.

[@RandomGeometryDashStuff]

04:36 do ios syscall numbers not change with kernel versions like linux?

[@bm1259]

thats probably normal behaviour for operating systems but ofc windows just has to be different

[@Dorumin]

@@bm1259 You'd think it's more of a problem than it really is. If Linux syscalls were so simple, there would be more Golangs that use it directly instead of libcs and musls :)

[@jeffsmithdawg]

Dude you’re like god level at reverse engineering. Did you ever create a jailbreak?

[@tomtravis858]

I wouldn't imagine so, it's a very different field of reverse engineering.

[@brycedotco]

Yea, I wish! I'm an app dev who dabbles in reverse engineering, not a reverse engineer who dabbles in app dev, unfortunately 😅

[@jeffsmithdawg]

@ you definitely have what it takes

[@super_loaf2]

my cat is currently watching this video with me

[@doshantgiradkar5307]

Loved your videos ❤️❤️, can you make them more frequently, like once a month if not week. And can you please also expand a little bit over to android side of things?

[@brycedotco]

Thank you!! I'm trying to make more of them this year! I have about zero expertise on the android side though - I want to learn, but we're probably a ways away from anything fun there!

[@neutrino2211_]

Your channel really needs to get in the eyes of more researchers, the RE content is always top notch

[@LiveLM]

At first I thought it was just cracking protection, but purposely exhausting the phone's memory is too far. Sketchy ass app, people should really quit using crap like this

[@sirflimflam]

This is very interesting. Could finding something like this result in getting the app taken off the app store? Seems a little crazy to force the entire phone to crap itself as a matter of design, regardless of the likelihood of activating. I don't think Apple would appreciate the implied instability of the phone. Granted you wouldn't theoretically run into this problem unless you were trying to debug the app, but the fact they have kill code like that at all would raise some eyebrows for me if I was determining the suitability for the app to be on the storefront.

[@aaronmaynard42]

I like your funny words magic man.

[@TheHackysack]

Sublime Text mentioned! Let's go!

[@AlekEagle]

16:53 would it be possible to compute what the shared folder would be and return that so resigned code would still work? Or does the iOS system prevent resigned packages from accessing shared folders from different signatures

[@shavranotheferanox7809]

saw this in reccomended, got curious cause it looked interesting, understood absolutely 0 things, sended it to my gf who likes to "poke around" in apps and things as well

[@darrenjones5688]

What’s the recommended device/version for jailbreak now? I’ve got an iOS 12 device but most apps won’t even install on it now.