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Facebook Is Giving Advertisers Access To Your Shadow Contact Information

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121–130 of 478 posts

Re: Facebook Is Giving Advertisers Access To Your Shadow Contact Information

#122

As an FB Marketing API developer, this has been available for several years . The way it works, advertisers can send their phone list to FB for ad targeting. However, phone hashes are sent, not clear ones. Personally, as long as the user has an opt-out and opt-in options, I don’t think ad targeting is necessarily an unethical pattern, the blurring lines of ads and recommendations would be actually a pattern that user…

>However, phone hashes are sent, not clear ones.

Lol! Phone numbers have less than 40 bits of entropy, it's trivial to break those hashes.

Re: Facebook Is Giving Advertisers Access To Your Shadow Contact Information

#123
post #30

Earlier quoted context omitted.

It would be really surprising if that was a facebook only thing. For starters Google pesters me at least as much to add my phone number to secure my account.

I think it will stop pestering you for a phone number if you give it some neutral second factor like a Security Key ? (Security Keys are actually way more anonymous than I'd even thought possible until I understood how they work, if you know Susie uses the same key for DropBox and GitHub, and you suspect Susie also uses this key for the account NumberOneSecretTrumpFan on GitHub, and then you steal all the account cre…

I'm not sure how it is now, but for a long time Google required you to enable SMS auth (by giving your phone number) before you could enable TOTP or other 2FA methods.

Re: Facebook Is Giving Advertisers Access To Your Shadow Contact Information

#124
post #105

I'm in a wired situation, I opened my facebook account with a phone number, not email, my username is phone number I had ~5 years ago. I lost the sim card ~4.5 years ago, so since then I still use the same login. Every time I login facebook asks me to update my phone number because it's no longer valid, so they probably know it's been recycled and someone else owns the number. Another thing... a year ago, I got a new…

It's admittedly off topic but if you don't mind me asking, what are the reasons for you to change your number every 1-2 years? Doesn't that complicate things with past clients, old friends and maybe even with family? I changed my number 3 years ago but I still keep my old number active because it occasionally gets calls or text from past contacts.

I don't use phones for communication, I much more relay on emails. My friend and family know how to contact me and they know that my phone number might stop working any time. I don't give phone numbers to clients, as I don't want to be disturbed when they want something, instead I respond to emails when I have time.

Re: Facebook Is Giving Advertisers Access To Your Shadow Contact Information

#125
post #25

The other really stupid thing, besides generally hurting the adoption of 2FA forever, is that they probably did it for hardly more than scraps, compared to their conventional add targeting capabilities. Maybe I am completely wrong about this, but I'm pretty convinced that almost all of the ad spending for that feature would have reached Facebook's coffers anyways had it not been available.

Same can be said about personally-targeted advertising in general. Really, how more effective is it?

Re: Facebook Is Giving Advertisers Access To Your Shadow Contact Information

#127
post #17

As a security engineer, I cannot overstate just how horrible this is. Phone numbers might not be an ideal 2nd factor for authentication, but to punish users for setting up 2FA by using the provided phone number for ad targetting is incredibly unethical.

I agree with your sentiment.

But, as someone who understands that not all people and companies use the same moral set as myself, this is why I've never set up 2fa using a phone.

Why should I give some company my phone number? Increasingly it's become a single point of metadata to uniquely describe myself (just as my email addresses have).

Re: Facebook Is Giving Advertisers Access To Your Shadow Contact Information

#129
post #9

Earlier quoted context omitted.

Who is still answering phone calls on their cell from numbers not in their contact book? If you call me and you're not in my phone my phones just dumps you direct to voicemail. Not excuse this behavior in the least, but robo calls in general are a solved problem for me.

Here's a typical problem: * Be in the US, get your mobile number years and years ago and it has the area code of where you lived at the time. * Move somewhere else, keep the mobile number. * Now you get 4-5 robocalls per day spoofing numbers from "your" area code and calling at reasonable hours for that area... which are not reasonable hours where you now live. And if you say "just turn on do not disturb", remember s…

I realize it's not a great option for lots of people, but the optimal solution is to choose a phone number with an area code far away from where you will ever have any legitimate contacts, and block everything from that area code.

Re: Facebook Is Giving Advertisers Access To Your Shadow Contact Information

#130
post #69

Earlier quoted context omitted.

Yep, something similar I discovered recently that if you sign up to Instagram with somebody's email that they use on Facebook then within a day or two you'll start to see all of their friends from Facebook whom are also on Instagram in your recommended follows. All of this happens without email verification..

> All of this happens without email verification This has very interesting consequences...

Whoa... so it was around in the open since around 2013, and still not fixed? 0_0
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