For the fingerprinting part, can you explain the difference with the JShelter browser extension (https://jshelter.org/)?
I checked as you did in your demo video with https://demo.fingerprint.com/playground (using JShelter in Firefox).
It produces a fingerprint detector report, like so :
Ooh nice, I haven’t seen this project! I actually tried attempting this as an extension at first but wasn’t able to override page window functions. I’m curious to know how they accomplished this. (edit: I see that I missed the chrome.scripting API facepalm)
Thank you for sharing :)
FWIW I still think a custom browser approach has some benefits (stealth and executing in out of process iframes. could be wrong on the second part, haven’t actually tested!)
This is such an eye opening, and really interesting. It reminded me of projects like XprivacyLua that "expose" the different calls and request from android apps. Great work!
Most of my job is reverse engineering a major website builder company's code so we can leverage their undocumented features. It's often a difficult job but your project could make it easier. I'm sure there are others out there that will find this useful.
Very cool, thanks for sharing. I would love to see this show up as an OSS project. I know a few people who would likely enjoy being able to contribute if that's something you'd be looking for.
Neat investigation but I didn’t totally follow how the project would be useful for reverse engineering, it seems like a project that would mostly be useful for evading bot checks like web scraping or AI automation.
This is neat but it also makes me uncomfortable to see just how much fingerprinting is done these days. TikTok is creepy but I'm sure they aren't the worst.
Someone mentioned this as well in another comment. Turns out most of this could’ve been done as an extension after all :-)
edit: actually, wouldn’t you still need to override the global you’d like to instrument? At that point, the toString of the modified function would leak your hook.
I have a project (in my rather long project backlog) that involves hooking JS APIs to download youtube videos. I'm worried that if my extension (or a similar extension) gained enough popularity, youtube would start inspecting the relevant JS objects to see if they'd been replaced with proxy instances.
Aside from playing a hooking/patching game of cat and mouse, I don't think this is fully solvable without modifying the browser engine itself - then you can hook things in a way that's completely transparent to the JS in webpages.
Thanks for sharing some examples! Someone shared a similar project in the other thread. I didn’t realize this at the time of writing haha.
FWIW I still think modifying the browser has some positives wrt stealth and hooking out of process frames (could be wrong on the second part, haven’t actually tested!)
Still good to know though will leave a note in the article :-)
Yeah, there's a pretty overwhelming amount of browser APIs and functionality which isn't always (well-)documented to learn about. If I recall correctly Proxies wouldn't be detectable (seems to be supported by https://exploringjs.com/es6/ch_proxies.html#sec_detect-proxi...) so long as your injected content script runs first (otherwise other code could presumably override the Proxy constructor). You should also be able to hook any embedded frames by setting `target: { ..., allFrames: true }`.
To note, there are undocumented detections to even Proxys, for example using `in` operator in v8 (such as `proxiedFunc in 1` for some proxied function). Really cool to see a project like this.
How do you use `in` in v8 to detect proxies? I assume its a difference in the exception, but the message and the cause were the same in both direct and proxied `x in 1`.
...and power users. This is a browser that acts in the interests of the user, something that the mainstream authoritarian technocracy is actively trying to destroy and has been ever since they removed "View Source" from its customary place.
"toString theory" is an incredible title for that section
Very interesting, thanks!
For the fingerprinting part, can you explain the difference with the JShelter browser extension (https://jshelter.org/)?
I checked as you did in your demo video with https://demo.fingerprint.com/playground (using JShelter in Firefox). It produces a fingerprint detector report, like so :
{
}However, it appears there is no way to display what was actually produced by the browser.
Was this the reason you had to build your own browser? Or is it possible to extend JShelter to do the same?
Ooh nice, I haven’t seen this project! I actually tried attempting this as an extension at first but wasn’t able to override page window functions. I’m curious to know how they accomplished this. (edit: I see that I missed the chrome.scripting API facepalm)
Thank you for sharing :)
FWIW I still think a custom browser approach has some benefits (stealth and executing in out of process iframes. could be wrong on the second part, haven’t actually tested!)
This is such an eye opening, and really interesting. It reminded me of projects like XprivacyLua that "expose" the different calls and request from android apps. Great work!
Most of my job is reverse engineering a major website builder company's code so we can leverage their undocumented features. It's often a difficult job but your project could make it easier. I'm sure there are others out there that will find this useful.
resworb nwo ym detnaw syawla ev'i dna reenigne esrever a m'I
This isn't rot13.
EDIT: Oh, it took me a minute!
Very cool, thanks for sharing. I would love to see this show up as an OSS project. I know a few people who would likely enjoy being able to contribute if that's something you'd be looking for.
Neat investigation but I didn’t totally follow how the project would be useful for reverse engineering, it seems like a project that would mostly be useful for evading bot checks like web scraping or AI automation.
This is neat but it also makes me uncomfortable to see just how much fingerprinting is done these days. TikTok is creepy but I'm sure they aren't the worst.
You can just use Proxy to get around toString shenanigans and prevent any detection whatsoever.
Someone mentioned this as well in another comment. Turns out most of this could’ve been done as an extension after all :-)
edit: actually, wouldn’t you still need to override the global you’d like to instrument? At that point, the toString of the modified function would leak your hook.
see: https://gist.github.com/voidstar0/179990efe918d1028b72f292cf...
Regardless, I do have some interesting ideas that should hopefully make my pain of compiling Chromium for 3 hours worth it though :p
Cheat Engine for site scripts? Who knows. Mostly just using this as an opportunity to learn some browser internals so id say it still paid off :)
Your example proxies the console object, the intended way in this case is to make a proxy from the log function itself and use the apply hook
toString will be called on the Proxy and not your hook so it won't reveal anything
D'oh! You are correct :-) Good catch and thanks for teaching me something!
Not to comment on the rest of article or the author's goals, but it's absolutely possible to use a content script (dynamically injected into the `main` world, as opposed to the default `isolated`, for example: https://github.com/tbrockman/browser-extension-for-opentelem...) and Proxy's (https://developer.mozilla.org/en-US/docs/Web/JavaScript/Refe...) to hook (most? if not all) Javascript being executed in the webpage transparently.
Which for some functionality would have been a bit more portable and involved less effort.
I have a project (in my rather long project backlog) that involves hooking JS APIs to download youtube videos. I'm worried that if my extension (or a similar extension) gained enough popularity, youtube would start inspecting the relevant JS objects to see if they'd been replaced with proxy instances.
Aside from playing a hooking/patching game of cat and mouse, I don't think this is fully solvable without modifying the browser engine itself - then you can hook things in a way that's completely transparent to the JS in webpages.
Thanks for sharing some examples! Someone shared a similar project in the other thread. I didn’t realize this at the time of writing haha.
FWIW I still think modifying the browser has some positives wrt stealth and hooking out of process frames (could be wrong on the second part, haven’t actually tested!)
Still good to know though will leave a note in the article :-)
Yeah, there's a pretty overwhelming amount of browser APIs and functionality which isn't always (well-)documented to learn about. If I recall correctly Proxies wouldn't be detectable (seems to be supported by https://exploringjs.com/es6/ch_proxies.html#sec_detect-proxi...) so long as your injected content script runs first (otherwise other code could presumably override the Proxy constructor). You should also be able to hook any embedded frames by setting `target: { ..., allFrames: true }`.
To note, there are undocumented detections to even Proxys, for example using `in` operator in v8 (such as `proxiedFunc in 1` for some proxied function). Really cool to see a project like this.
How do you use `in` in v8 to detect proxies? I assume its a difference in the exception, but the message and the cause were the same in both direct and proxied `x in 1`.
...and power users. This is a browser that acts in the interests of the user, something that the mainstream authoritarian technocracy is actively trying to destroy and has been ever since they removed "View Source" from its customary place.
Interesting tool. Would love to contribute
feature request: allow setting breakpoints without having obfuscator debugger statement loops get in the way
I actually wrote a separate blog post about this! Changing the debugger keyword :) see: https://nullpt.rs/evading-anti-debugging-techniques
could be very useful for my work, nice to see