Facebook makes its money from ads, we know that and that involves gathering data from its users and serving targeted ads to them. It is a business model that works very well with them and makes them a lot of money if you care to see their financials every quarter.
However some of these practices are quite controversial and the company has been under the radar recently of how they serve this ads.
From a Gizmodo report, the author decided to do an experiment using Facebook’s Custom Audience feature. The theory was Facebook was letting advertisers target users with ways they had previously said it won’t work.
Well apparently, in addition to the contact information you willing add to your profile, Facebook is also using contact information you handed over for security purposes (2 factor authentication) and also contact information you didn’t hand over at all. The latter was obtained from people’s contact books, which is not surprising since you can allow Facebook to sync your entire contacts to it and the chances are there to match these details. This info is your ‘shadow profile’ as the author puts it and decided to test out the theory.
There are researchers who found out that if you gave Facebook a phone number for two factor authentication to receive those alerts, that number became targetable by an advertiser within weeks. They also found out if A shares her contact list that contains B’s previously unknown phone number, advertisers would be able to target B with an ad using that number. Now B can’t access that ‘shadow’ information since apparently it would violate A’s privacy so B can’t see it or delete it.
Now the author was able to place an ad to a certain recipient by targeting his ‘shadow profile’. The ad was directed to display to a Facebook account connected to the landline number of the person being targeted of which the number was never provided to Facebook before and apparently, the recipient saw the ad within hours.