You Gave Facebook Your Number For Security. They Used It For Ads

Gennie Gebhart at the EFF (September 27, 2018) wrote You Gave Facebook Your Number For Security. They Used It For Ads.

Add “a phone number I never gave Facebook for targeted advertising” to the list of deceptive and invasive ways Facebook makes money off your personal information. Contrary to user expectations and Facebook representatives’ own previous statements, the company has been using contact information that users explicitly provided for security purposes—or that users never provided at all—for targeted advertising.

A group of academic researchers from Northeastern University and Princeton University, along with Gizmodo reporters, have used real-world tests to demonstrate how Facebook’s latest deceptive practice works. They found that Facebook harvests user phone numbers for targeted advertising in two disturbing ways: two-factor authentication (2FA) phone numbers, and “shadow” contact information.

Facebook is also grabbing your contact information from your friends. This means that, even if you never directly handed a particular phone number over to Facebook, advertisers may nevertheless be able to associate it with your account based on your friends’ phone books.
--