- Facebook uses contact information requested for “security purposes” (ie cell phone #’s for Two-Factor authentication) and contact info provided by friends when they use the “Find Friends” feature to target ads.
- This contact info Facebook claims not to use is compared to contact info advertisers already have about users to target ads more effectively.
- Researchers performed several experiments proving that User A sharing contact info about User B resulted in User B viewing new targeted ads.
Facebook Is Giving Advertisers Access to Your Shadow Contact Information
(09/26/2018)