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Reverse Engineering Snapchat (Part II): Debofuscating the Undeobfuscatable

hot3eed.github.io

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Re: Reverse Engineering Snapchat (Part II): Debofuscating the Undeobfuscatable

#54

Post by reagent_finder »

saagarjha wrote: post #12
hackernewsn00b wrote: post #10

Hey OP, since you're here: I find this pretty hard to follow. Would you be open to writing a longform version of this aimed at the tutorial level? Reading between the lines, I would guess you're trying to demonstrate that you really know what you're doing. Maybe as a proof of concept for possible employment opportunities. If so, that's great! Good luck. But if I were interested in reverse engineering some other app,…

I found it fairly reasonable, although you'd have to have a general idea of the subject beforehand. I read it as a being aimed at reverse engineers who are looking for some general techniques to bypass common anti-debugging/obfuscation features rather than "how to reverse engineer apps 101".

"Reasonable" is a stretch, "interesting" is the right word. Personally I'd put this in the "Oh, huh" box along with quantum crypto. It's interesting, it's complex and it's got way too many engineering hours behind it... but ultimately for 99% of people or even 99% of computer scientists or HN readers, it's just fascinating trivia.

I absolutely appreciate these posts, this guy spent WEEKS delving into the depths of SnapChat just for the joy of discovery.

Maybe a good classification would be that part 1 is detailing a number of obfuscation techniques and the key thing to take away is that all of them CAN be bypassed.

Re: Reverse Engineering Snapchat (Part II): Debofuscating the Undeobfuscatable

#56

Post by 3eed »

sintax wrote: post #52

For MBA, there's also Arybo[1] from Quarkslab. Never used it and seeing the reference to SSPAM, I assume the author is aware of the tool. [1] https://github.com/quarkslab/arybo

I came across Arybo while working on the binary but I can't remember why I didn't use it, this is vague memory now. Anyway it does the job in one go, I added an edit.

Re: Reverse Engineering Snapchat (Part II): Debofuscating the Undeobfuscatable

#57

Post by power78 »

zemnmez wrote: post #43
zimmerfrei wrote: post #41

Both iOS and recent Androids have by now a form of app attestation: the server can tell if the caller is the legitimate app or not (with good enough confidence - as everything, it's not unbreakable). Doesn't that make obfuscation kind of pointless? Even if your knock-off app knows everything about the API of the original service, it won't be able to use it because it is not the genuine app or maybe it is but it is no…

seems like something having a rooted os would fix pretty quickly

Seems like the creator of Magisk Manager could not get around Android's implementation: https://twitter.com/topjohnwu/status/1245956080779198464?s=1...

Re: Reverse Engineering Snapchat (Part II): Debofuscating the Undeobfuscatable

#58

Post by foobar_ »

wayne wrote: post #13

This level of API obfuscation reminds me of forever ago when MSN Messenger figured out AOL's AIM API, so MSN Messenger could send AIM messages, which annoyed AOL. AOL would make API changes to break MSN, but MSN would update the client and stay ahead. Eventually to make the API uncloneable, AOL changed their payload to exploit a buffer overrun in their own AIM clients that wouldn't be in the MSN clients. https://nplu…

Can't AOL use some kinda session token for this ? Super confused.

Re: Reverse Engineering Snapchat (Part II): Debofuscating the Undeobfuscatable

#59

Post by telotortium »

sanqui wrote: post #42
ATsch wrote: post #34

Earlier quoted context omitted.

Especially trademark violations are very effective for this. For example the original GameBoy used it as DRM. The cartridge had to contain a Nintendo(R) logo which was displayed on boot to work, a legal deterrent for publishing unlicensed games that still works to this day.

Except that the use of copyrighted and trademarked data for means of enabling interoperability has been ruled fair use in the Sega v. Accolade[1] case. So I believe Nintendo's use of the logo in this way is not much more than snake oil. [1] https://en.wikipedia.org/wiki/Sega_v._Accolade

That case was decided after the initial release of the Game Boy, so it wasn't an unreasonable thing to try at the time.

Re: Reverse Engineering Snapchat (Part II): Debofuscating the Undeobfuscatable

#60

Post by timClicks »

sanqui wrote: post #42
ATsch wrote: post #34

Earlier quoted context omitted.

Especially trademark violations are very effective for this. For example the original GameBoy used it as DRM. The cartridge had to contain a Nintendo(R) logo which was displayed on boot to work, a legal deterrent for publishing unlicensed games that still works to this day.

Except that the use of copyrighted and trademarked data for means of enabling interoperability has been ruled fair use in the Sega v. Accolade[1] case. So I believe Nintendo's use of the logo in this way is not much more than snake oil. [1] https://en.wikipedia.org/wiki/Sega_v._Accolade

Gentle reminder that the USA isn't the only jurisdiction. In countries without fair use, for example, this wouldn't even be able to be applied.
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