Reverse engineering the obfuscated TikTok VM
1–10 of 131 posts
Re: Reverse engineering the obfuscated TikTok VM
#2The fascinating process of reverse engineering this VM is detailed here.
TikTok uses a custom virtual machine (VM) as part of its obfuscation and security layers. This project includes tools to:
Deobfuscate webmssdk.js that has the virtual machine.
Decompile TikTok’s virtual machine instructions into readable form.
Script Inject Replace webmssdk.js with the deobfuscated VM injector.
Sign URLs Generate signed URLs which can be used to perform auth-based requests eg. Post comments.
Re: Reverse engineering the obfuscated TikTok VM
#3This seems like quite a lot of work to hide the code. What would the legitimate reasons for this be? Because it looks like it would make the program less optimized and more complexity just leads to more errors.
I understand the desire to make it harder for bots, but 1) it doesn't seem to be effective and bots seem to be going a very different route 2) there's got to be better ways that are more effective. It's not like you're going to stop clones through this because clones can replicate by just seeing how things work and reverse engineer blackbox style.
Re: Reverse engineering the obfuscated TikTok VM
#4There is no legitimate reason for a social media platform to employ this much obfuscation.
Re: Reverse engineering the obfuscated TikTok VM
#5Very impressive work! I always enjoy a good write up about reverse engineering efforts and yours was really simple to follow.
Many popular/large websites and bot protection services usually have environment checking as a baseline and mouse-movement tracking in some of the more aggressive anti-bot checks.
It's always interesting to see how long it takes from when the measures have been defeated/publicised until the service ends up making changes to their mechanism to make you start over (hopefully not from scratch).
Re: Reverse engineering the obfuscated TikTok VM
#6This seems like quite a lot of work to hide the code. What would the legitimate reasons for this be? Because it looks like it would make the program less optimized and more complexity just leads to more errors. I understand the desire to make it harder for bots, but 1) it doesn't seem to be effective and bots seem to be going a very different route 2) there's got to be better ways that are more effective. It's not li…
Making it harder for bots usually means that it drives up the cost for the bots to operate; so if they need to run in a headless browser to get around the anti-bot measures it might mean that it takes, for example, 1.5 seconds to execute a request as compared to the 0.1 seconds it would without them in place.
On top of that 1.5 seconds is also that there is a much larger CPU and memory cost from having to run that browser compared to a simple direct HTTP request which is near negligible.
So while you'll never truly defeat a sufficiently motivated actor, you may be able to drive their costs up high enough that it makes it difficult to enter the space or difficult to turn a profit if they're so inclined.
Re: Reverse engineering the obfuscated TikTok VM
#7The fascinating process of reverse engineering this VM is detailed here. TikTok uses a custom virtual machine (VM) as part of its obfuscation and security layers. This project includes tools to: Deobfuscate webmssdk.js that has the virtual machine. Decompile TikTok’s virtual machine instructions into readable form. Script Inject Replace webmssdk.js with the deobfuscated VM injector. Sign URLs Generate signed URLs whi…
Is calling a massive embedded JS obfuscator a "VM" a bit of a stretch? Ultimately it's not translating anything to a lower-level language.
Still, I had no idea. This is really taking JS obfuscation to the next level.
One kind of wonders, what is the purpose of that level of obfuscation? The naive take is that obfuscation is usually to protect intellectual property... but this is client-side code that wouldn't give away anything about their secret sauce algorithm.
Re: Reverse engineering the obfuscated TikTok VM
#8This seems like quite a lot of work to hide the code. What would the legitimate reasons for this be? Because it looks like it would make the program less optimized and more complexity just leads to more errors. I understand the desire to make it harder for bots, but 1) it doesn't seem to be effective and bots seem to be going a very different route 2) there's got to be better ways that are more effective. It's not li…
A generous take would be that they have their own internal GUI tools that make it easier for non-programmers to set up visual elements in this. That was historically the reason to invent VMs like Flash. A less generous take would account for the enormous potential for hiding nefarious code inside such a thing, and account for the nature of the government which deployed it, and conclude that it was a national security / defense project disguised as a candy-coated trojan horse.
Re: Reverse engineering the obfuscated TikTok VM
#9This seems like quite a lot of work to hide the code. What would the legitimate reasons for this be? Because it looks like it would make the program less optimized and more complexity just leads to more errors. I understand the desire to make it harder for bots, but 1) it doesn't seem to be effective and bots seem to be going a very different route 2) there's got to be better ways that are more effective. It's not li…
Makes it easier to hide code that does browser fingerprinting.
Re: Reverse engineering the obfuscated TikTok VM
#10The fascinating process of reverse engineering this VM is detailed here. TikTok uses a custom virtual machine (VM) as part of its obfuscation and security layers. This project includes tools to: Deobfuscate webmssdk.js that has the virtual machine. Decompile TikTok’s virtual machine instructions into readable form. Script Inject Replace webmssdk.js with the deobfuscated VM injector. Sign URLs Generate signed URLs whi…
Is calling a massive embedded JS obfuscator a "VM" a bit of a stretch? Ultimately it's not translating anything to a lower-level language. Still, I had no idea. This is really taking JS obfuscation to the next level. One kind of wonders, what is the purpose of that level of obfuscation? The naive take is that obfuscation is usually to protect intellectual property... but this is client-side code that wouldn't give aw…
VM obfuscation is a common technique for malware developers.
The VM term is applied because the obfuscator creates a custom instruction set and executes custom byte code. This is generated per build.