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Ask HN: Do ISP's inject ads into browsers?

2 points by HoppedUpMenace ↗ HN
Just noticed that an item that was heavily Google searched on one device in my home was now showing up as an advertisement on another device that was using Internet Explorer. This device is purely used for work and that has never once been used for searching for this item or anything remotely related to it. I find this very disturbing, albeit highly coincidental, and I cannot draw any other conclusion (additionally, no other devices pair or interface with the work device in question).

9 comments

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sp332
https://ads.google.com/intl/en_uk/home/resources/retargeting...

Your ISP can see your DNS queries at least, and might sell that data. But they probably don't know which specific items you searched for because that data is encrypted between you and Google.

Vladimof
even if they can't see your DNS queries, they still know a lot (you can switch DNS server)
sp332
That's true, even if you switch DNS, they can still see the destination IP of every connection you make. That still means they can't see individual search terms though.
HoppedUpMenace
So should I switch to Firefox on everything or VPN or just erase cookies every session?
Vladimof
You could also use the Tor Browser...
sp332
Well, if you can find a VPN that's more trustworthy than your ISP. Some of them are pretty sketchy too.

I think disabling third-party cookies helps a lot. If each site can only see its own cookies, it's harder to coordinate. Also, browsers have started experimenting with separate cookie jars for each top-level domain. https://techcrunch.com/2021/02/24/mozilla-beefs-up-anti-cros...

Vladimof
> That still means they can't see individual search terms though.

they can't see search terms with HTTPS

dave4420
Is it possible that the ads are served by Google, and that Google infers your devices belong to the same household because they share the same IP address?
Nextgrid
Any ad provider worth its salt would absolutely be doing this.