Facebook Asked Users for Their Phone Numbers to Enhance Security, then Used the Information to Sell More Ads

Facebook “shadow contact information” is a new term to describe how the social network harvested more user data to sell even more ads…

Two-factor authentication or 2FA, is security measure which helps to protect people from hacks and other nefarious behavior. It’s used by many digital entities to help keep their members’ information safe. But, Facebook uses it for a different purpose — to sell more advertising.

Facebook Shadow Contact Information Gathered to Sell Ads

A group of researchers from Northeastern University and Princeton University used real-world tests to demonstrate how Facebook deceives its users into giving up even more personal information. The social network harvests phone numbers from unsuspecting users through two stealth methods: two-factor authentication and “shadow contact information.”

First, Facebook prompted people to beef-up their account security with 2FA. Then, Facebook sold the information to advertisers within a matter of weeks. But, it doesn’t end there. The social network took its data mining efforts a step further. 

Second, Facebook used 2FA phone numbers to essentially grab contact information. Meaning, Facebook then targets others who haven’t directly turned over their phone numbers with ads.

Here’s how Facebook shadow contact information works: User A, or let’s call him “Davey,” shares his contacts with Facebook, which includes a number previously unknown to the social corporation, User B, or someone we’ll call “Lisa.” Now that Facebook has “Lisa’s” phone number, it sells her information to advertisers.

Making matters worse, is the fact Facebook provides no explicit disclosure of this practice in the Contact and Basic Info section. Furthermore, European users can’t even find such a disclosure, despite explicit requirements under the GDPR that a company give users a “right to know” what information it has on them.

Owen E. Richason IV

Owen is blog content writer, SEO consultant, social media marketer, and website guy. His work has appeared in the Houston Chronicle, on Business.com, Tampa Bay Business and Financier, AOL and numerous other blogs and websites. is also a musician and is the founder of Groove Modes.