Reddit’s online page makes employ of DRM for fingerprinting (2020)

Recently, I was using a page on Reddit (i.e. the main redesign domain, not, when I saw a yellow bar from Firefox: Why did Reddit want to use DRM? This pop-up was appearing on all pages, even on pages with no audio or video. To find out, I did a bunch of source code…

Reddit’s online page makes employ of DRM for fingerprinting (2020)

Now not too prolonged ago, I was the utilization of a page on Reddit (i.e. the principle redesign area, not, when I noticed a yellow bar from Firefox:

Reddit asking for permission to use DRM

Why did Reddit wish to make employ of DRM? This pop-up used to be exhibiting on all pages, even on pages and not utilizing a audio or video. To rep out, I did a bunch of offer code diagnosis and discovered out.

Reddit’s offer code makes employ of bundling and minification, but I was able to infer that in ./src/reddit/index.tsx, a script used to be conditionally loaded into the page. If the show_white_ops A/B take a look at flag used to be location, then it loaded one other script: That script hundreds (regardless that it looks to take a look at for a browser trojan horse involving running JSON.parse with null bytes, and generally hundreds as an different, but I haven’t analyzed this file (it looks rather identical despite the incontrovertible truth that), and also does nothing if in consequence of one other browser trojan horse, !("a"=="a"[0]) evaluates to correct form).

The explanation of all of this appears to be both fingerprinting and combating advert fraud. I’ve determined that belongs to White Ops. (edit: they’ve just just lately rebranded to HUMAN) I like infered this from the name of Reddit’s characteristic flag, and mentions of White Ops which is a “global leader in bot mitigation, bot prevention, and fraud safety”. They seem to raise out this by amassing tons of information regarding the browser, and examining it. I must explain, their way may be very spectacular.

Abet to the DRM mission, evidently the script is checking what DRM solutions shall be found, but not essentially the utilization of them. On the different hand, staunch checking is ample to location off Firefox into exhibiting the DRM popup. Specfically, it looks for Widevine, PlayReady, Clearkey, and Adobe Primetime.

fundamental.js does a bunch of assorted interesting issues, but there’s so many who I’ve written a total seperate blog put up about all of those I discovered. Listed right here are some highlights:

  • Contains what appears to be a Javascript engine JIT exploit/trojan horse, "haha jit trot brrrrr" looks in a segment of the code that appears to be doing something unfamiliar with math operations.
  • Has an obfuscated reference to res://ieframe.dll/acr.js, which will doubtless be used to take advantage of primitive Cyber web Explorer variations (I deem)
  • Many tests for various global variables and varied indicators of headless and computerized browsers.
  • Sends files to and
  • Assessments if devtools is open
  • Detects installed text to speech voices
  • Assessments if browsers like floating point errors when rounding 0.49999999999999994 and 2^52
  • Detects if some Chrome extensions are installed
  • Assessments if characteristic bodies that are performed in the browser like [native code] when stringified
    • it accumulate’s kinda meta, it tests if toString itself is performed in native code (regardless that it doesn’t trot any ranges deeper than files)
  • Assessments for Apple Pay enhance

Irregular. Thanks for studying.

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“Simplicity, patience, compassion.
These three are your greatest treasures.
Simple in actions and thoughts, you return to the source of being.
Patient with both friends and enemies,
you accord with the way things are.
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