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Ask HN: How has Facebook figured out my family doctor as a friend suggestion?

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Re: Ask HN: How has Facebook figured out my family doctor as a friend suggestion?

#31

Post by williamscales »

compsciphd wrote: post #11

We've gone through this many times, its nothing nefarious. 1) doctor uploads his contacts (phone number/email addresses) to facebook and sets his contact info 2) you upload your contacts and set your contact info if there's one match between them, facebook believes (correctly) that there is some sort of existing relationship between you. The fact that its professional and not personal and you want facebook to just be…

I think the original asker said he had never uploaded his contacts. Presumably though Facebook could just follow the reverse relation from the doctor without needing to confirm that it goes both ways.

Re: Ask HN: How has Facebook figured out my family doctor as a friend suggestion?

#32

Post by code_duck »

The most unusual friend suggestion I have received is a profile for the actor Steve Martin. It had two mutual friends, and appeared 20 minutes after a friend asked me "Have you ever listened to Steve Martin? The actor? He's also a bluegrass musician" and played a couple of songs on Spotify.

Any ideas on how that came about? It's hard to believe it's anything other than some app listening to audio.

Re: Ask HN: How has Facebook figured out my family doctor as a friend suggestion?

#33

Post by caseysoftware »

compsciphd wrote: post #11

We've gone through this many times, its nothing nefarious. 1) doctor uploads his contacts (phone number/email addresses) to facebook and sets his contact info 2) you upload your contacts and set your contact info if there's one match between them, facebook believes (correctly) that there is some sort of existing relationship between you. The fact that its professional and not personal and you want facebook to just be…

There doesn't have to be a match. Simply the fact that either person either uploads their contacts (either via linking to their email or installing Facebook on their phone) is enough to assume the link.

After all, if you have someone in your contact list (phone or email), you've probably been in touch at least once.

Nefarious? Debatable. But also totally predictable.

Re: Ask HN: How has Facebook figured out my family doctor as a friend suggestion?

#34

Post by caseysoftware »

patcheudor wrote: post #15
simonduponte wrote: post #7

Factors that contribute to friend suggestions on FB: 1. Facebook tracking pixels on websites (if you visit a website with the pixel, you can be targeted in many different ways). 2. Email. If you have sent or received an email to the doctor, and either of you has associated that email to FB, you can be tracked. 3. Searching on FB, you say its unlikely for him to look you up on FB, yet theres always a chance that being…

I'm glad you covered the bi-directional aspects of the association. A number of years ago FB had a vulnerability I discovered whereby it was possible to register an account with an e-mail you don't own. Obviously it wouldn't be possible to then verify the account if the owner of the e-mail targeted failed to click on the verify link. To get around this, upon first authenticating with the account after registration it…

This was easy to do as late as 2010. I haven't tried it recently but it was a common attack for quite a while:

https://caseysoftware.com/blog/social-media-for-social-evil-...

Re: Ask HN: How has Facebook figured out my family doctor as a friend suggestion?

#35

Post by nscalf »

code_duck wrote: post #32

The most unusual friend suggestion I have received is a profile for the actor Steve Martin. It had two mutual friends, and appeared 20 minutes after a friend asked me "Have you ever listened to Steve Martin? The actor? He's also a bluegrass musician" and played a couple of songs on Spotify. Any ideas on how that came about? It's hard to believe it's anything other than some app listening to audio.

Do you log into spotify through facebook?

Re: Ask HN: How has Facebook figured out my family doctor as a friend suggestion?

#38

Post by calvinbhai »

Possibilities:

1) you have instagram or whatsapp and use them frequently

2) you use an app that has Facebook login, that has location access or just has the SDK lying in app but not being used.

3) I don't know about what access react native/js frameworks have in terms of device resources, but that "may be" an another source of info leak.

4) your contacts/friends uploaded a photo on one of these services where you were there in the photo

5) if any of these apps have microphone access (when you record videos) it's "possible" to do many surreptitious things.

All of the above, done by 1 or many of your friends/contacts on Facebook/instagram/WhatsApp, FB identified you and correlated it somehow.

Re: Ask HN: How has Facebook figured out my family doctor as a friend suggestion?

#39

Post by ceejayoz »

pmiller2 wrote: post #20
badthingfactory wrote: post #5

I had a surgical procedure done at the beginning of the year. I hadn't explicitly shared this information at any point online or visited any websites related to the surgery. A few days after visiting the hospital for some tests, Google AdSense was showing me ads for surgeons at that specific hospital. I'm not sure who I was most disappointed in. The hospital for purchasing the ad, Google for tracking my hospital visi…

And, to top it all off, those ads were utterly ineffective, since you'd already had the procedure done! Amazon and eBay have this same problem, wherein they show you things similar to things you've already bought.

> Amazon and eBay have this same problem, wherein they show you things similar to things you've already bought.

Which is especially silly when it's something you'd only buy once. "Oh, you bought a table saw? Why not fifteen more?!"

Re: Ask HN: How has Facebook figured out my family doctor as a friend suggestion?

#40

Post by naner »

jedimastert wrote: post #26
yjftsjthsd-h wrote: post #19

Earlier quoted context omitted.

I think we could reasonably disagree about whether or not it's nefarious. Siphoning everyone's contacts is iffy to start with.

It's not exactly without consent

Everyone in the contact list didn't provide consent. Facebook better understands the privacy implications here more than individual users so I don't see anything wrong with placing most of the blame on Facebook.
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