[godelski]

This 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.

[noduerme]

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.

[supriyo-biswas]

VM-based architectures are really common in the obfuscation space, which is why you have executable packers[1], JS packers[2] and bot management products[3][4] leveraging similar techniques.

As for why the obfuscation is needed: bot management products suffer from a fundamental weakness in that ultimately, all of them simply collect static data from the environment, therefore it would make much more sense to make the steps involved as difficult to reverse engineer as possible. Once that is done, all you need to do is slightly change the schematics of your script every few weeks and publish a new bundle, and you've got yourself a pretty unsubvertible* protection scheme.

Regarding the "trojan horse", I think someone is yet to show proof that it's a Javascript exploit.

(*Unsubvertible is obviously relative, but raising the cost the attack, from say, $0.01/1000 requests to $10/1000 requests would massively cut down on abuse.)

[1] https://vmpsoft.com/

[2] https://jscrambler.com/

[3] https://github.com/neuroradiology/InsideReCaptcha

[4] https://www.zenrows.com/blog/bypass-cloudflare#_qEu5MvVdnILJ...

[davidsojevic]

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.

[godelski]

I understand the argument. You can't have perfect defense and speedbumps are quite effective. I'm not trying to disagree with that.

But it does not seem like the solution is effective at mitigating bots. Presumably bots are going a different route considering how prolific they are, which warrants another solution. If they are going through this route then it certainly isn't effective either and also warrants another solution.

It seems like this obscurification requires a fair amount of work, especially since you need to frequently update the code to rescramble it. Added complexity also increases risks for bugs and vulnerabilities, which ultimately undermine the whole endeavor.

I'm trying to understand why this level of effort is worth the cost. (Other than nefarious reasons. Those ones are rather obvious)

[rfoo]

Google has been doing this since forever for recaptcha. And, to be fair, it seems to be fairly effectively for bot detection.

https://github.com/neuroradiology/InsideReCaptcha

> bots seem to be going a very different route

If the "very different route" means running a headless browser, then it's a success for this tech. Because the bot must run a blackbox JS now, and this gives people a whole new street of ways to run bot detection, using the bot's CPU.

[godelski]

Okay... but those bots exist... and in high numbers... By "very different route" I mean "measure to effectively stop the bots" (or dramatically reduce). It seems like if they're using a headless browser then they're still being quite effective in accomplishing their goals.

[mike_hearn]

Google's obfuscating VM based anti-bot system (BotGuard) was very effective. Source: I wrote it. We used it to completely wipe out numerous botnets that were abusing Google's products e.g. posting spam, clickfraud, phishing campaigns. BotGuard is still deployed on basically every Google product and they later did similar systems for Android and iOS, so I guess it continues to work well.

AFAIK Google was the first to use VM based obfuscation in JavaScript. Nobody was using this technique at the time for anti-spam so I was inspired primarily by the work Nate Lawson did on BluRay.

What most people didn't realize back then is that if you can force your adversary to run a full blown web browser there are numerous tricks to detect that the browser is being automated. When BotGuard was new most of those tricks were specific to Internet Explorer, none were already known (I had to discover them myself) and I never found any evidence that any of them were rediscovered outside of Google. The original bag of tricks is obsolete now of course, nobody is using Internet Explorer anymore. I don't know what it does these days.

The VM isn't merely about protecting the tricks, though. That's useful but not the main reason for it. The main reason is to make it easier to generate random encrypted programs for the VM, and thus harder to write a static analysis. If you can't write a static analysis for the program supplied by your adversary you're forced to actually execute it and therefore can't write a "safe" bot. If the program changes in ways that are designed to detect your bot, done well there's no good way to detect this and bring the botnet to a safe halt because you don't know what the program is actually doing at the semantic level. Therefore the generated programs can detect your bot and then report back to the server what it found, triggering delayed IP/account/phone number bans. It's very expensive for abusers to go through these bans but because they have to blindly execute the generated programs they can't easily reduce the risk. Once the profit margin shrinks below the margin from abusing a different website, they leave and you win.

[throwaway48476]

Makes it easier to hide code that does browser fingerprinting.

[Scaevolus]

Obfuscation is one part of defense in depth. Tiktok also has a variety of captchas to block scrapers, independent of this.

None of it's perfect, and they can be worked around, but by providing a barrier you've restricted some of the bad actors (spambots, scrapers) from acting at all.

It's easier to deal with 100 spambots than 1000!

[like_any_other]

Unless the scrapers are DDoSing the site, I refuse to consider the downloading of publicly posted data as malicious. It shows how captured the conversation has become by corporate interests, that viewing or storing data posted free of charge, publicly, by their users, in a way not approved by that corporation, is seen as malicious, and the only morally allowed way to view it is to use their spyware-laden client.

[areyourllySorry]

this is also a measure against bots that write, not just those that read

[Scaevolus]

What if the user has disabled downloads of a video? Should the creator (and copyright owner) of a piece of media not be allowed even token attempts to prevent copying?

[ndriscoll]

No because that interferes with fair use. If someone publicly posts a video, everyone has the right to copy it without any permission or awareness from the original author for things like commentary/criticism (it would be silly to require the copyright owner's permission to criticise a work!).

[hoseja]

Here's a great way to prevent people copying your precious video: don't post in on the internet.