Ask HN: How does Facebook know my Google searches? | Hacker News Reader

Ask HN: How does Facebook know my Google searches?

9 pointsbrad07 comments

I was doing some work on a side project earlier today and Googled "pug" for pug.js. Google returned results about dogs instead, so I clarified my search to pugjs and thought nothing more of it.

I've just logged into my Facebook account tonight and it has two suggested groups on the right hand side. "Pug Crazy" and "Passionate about Pugs", both dog related.

How the hell has Facebook linked my Google searches to my Facebook account? I just mentioned it to some family that said they've experienced the same thing from searching a camping spot. Is it time to nuke all my accounts from orbit?

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EDIT

I used two Chrome profiles with the following extensions:

dev - 1Password, Adblock Plus, Click&Clean, Privacy Badger

personal - 1Password, Adblock Plus, Chrome Remote Desktop, Click&Clean, cookies.txt, Privacy Badger, Save to Pocket

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Several businesses paid Google to show you advertisements for canine pugs. Note that Google did not collect revenue from the purchasers to show canine pug advertising to someone. Google charged to show it to you.

The advertisers spent the money and got the data and correlated it with all the other data they have...including things like the fact you use Chrome and have four specific extensions and which country you are in and probably your ISP and the state of your microphone and whether you have a GPU to perform WebGL and if so how fast it is and the round trip latency to some CDN and a bunch of other stuff and all this anonomyzes you down to a market segment of size = one.

Really smart people have been sitting around all day year in and year out for decades figuring out how to track consumer behavior because there is big money in it. It wasn't invented with the cookie two decades ago. The cookie was an implementation detail of work credit card companies started two decades or more prior.

Good luck.

I'm assuming you're referring to browser fingerprinting.

If you want to know how unique you are you can check EFF's Panopticlick https://panopticlick.eff.org/

Next question: How does anyone guard against this? My canvas fingerprint is 12 bits of identifying info even though I have what I would consider to be a fairly common MacBook Pro. Between this and my WebGL fingerprint (11 bits) I'm most likely uniquely identifiable.

IP addresses probably have three or four bits of entropy at best: home, work, mobile, school, a few free wifi locations. Browser fingerprinting is an alternative when the data isn't already available. I just riffed on it as an example of the asymmetry of the information conflict between individual and organizations armed with many many data centers.

My theory: one of the pug.js related websites had a Facebook like/share button. Facebook took the hint that you're interested in something pug related because it mis-classified the domain/page.

I use Privacy Badger on Chrome, which should block all social widgets by default. I'd be surprised if this was the vector.

Just looking from outside the square, is it possible that the Facebook cookie on your machine is interrogating the Google cookie or your browse history?

From memory I logged in to Facebook using my personal Chrome profile and I searched for pug.js on my development Chrome profile.

I'm fairly sure I opened the pug search on my dev profile but it's possible I opened it on my personal one by mistake.

Every time my chrome Profile window is closed it wipes all cookies/history/local storage etc. using Click & Clean. https://chrome.google.com/webstore/detail/clickclean/ghgabhi...

Either way it seems Facebook is acquiring user data in a really creepy way.

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