Researchers Found Facebook's Ad Targeting On 'Shadow' Profiles: Facebook Admits It

Facebook is one huge social media network. As sophisticated as it can be, its targeting and tracking methods are more than what people have bargained for.

One discovery began when a study by researchers at Northeastern University and Princeton University, found that phone numbers given to Facebook for two-factor authentication (2FA) were also used to target advertising to users.

They discovered this targeting method when the researchers were looking into how ad targeting really works on Facebook.

Two-factor authentication is an option intended to enhance security by requiring a second step, such as entering codes sent via text messages, as well as passwords, before users can login into their accounts. Apparently, those phone numbers that were added to profiles for security purposes or for messaging were potential fodder for advertisers, according to the study.

At first, Facebook denied doing this. But it later confirmed that advertisers can indeed use 'shadow' phone numbers to serve up targeted advertisements.

How does Facebook decide which ads to show me and how can I control the ads I see
How Facebook decides which ads to show, and how users can control the ads they see (Facebook Help page)

Shadow profiles may include phone numbers or emails that might not be visible on one's profile, but can be collected from other people’s contact books. They sit in a hidden layer, hence the name "shadow profile."

The social media giant acknowledged that it uses contact information uploaded to users' profiles for ad targeting purposes, sharing personally identifying information that users never submitted to the social network with its advertisers.

This way, Facebook advertisers can use this hidden layer of personal information to target users with ads, even if they have restricted information access to advertisers.

What this means, Facebook is not only using the information users have willingly on Facebook for advertising, but also use contact information meant for security purposes, and also contact information users never handed over at all.

Facebook has given advertisers the ability to target ads by phone numbers. What they need to do, is to only upload the phone number and email addresses they collected to Facebook, and leave Facebook do the rest. Facebook calls this a custom audience, allowing advertisers to sell to people they know are already interested in their product or service.

The only problem here is that, those advertisers can also target people who gave their phone number to Facebook, thinking that it would only be used for security reasons. They have no knowledge of their contact details are being given by Facebook to those advertisers.

The researchers discovered this when they were testing whether Facebook was using shadow contact by uploading hundreds of landline phone numbers.

How can I adjust how ads are targeted to me based on my activity on or off of Facebook?
How users can adjust how ads are targeted to them based on their activity on or off of Facebook (Facebook Help page)

Facebook, the Silicon Valley-based titan, has already faced intense global scrutiny over the mass harvesting of personal data by Cambridge Analytica, a British political consultancy that worked for Donald Trump's 2016 election campaign.

The company admitted that up to 87 million users may have had their data hijacked in the scandal.

And for this 'shadow' profile ad-targeting method, Facebook didn't reject the study's findings, as the company's spokesperson explained:

"We use the information people provide to offer a better, more personalized experience on Facebook, including ads. We are clear about how we use the information we collect, including the contact information that people upload or add to their own accounts. You can manage and delete the contact information you've uploaded at any time."

Users can opt out of this unethical targeting experience by opting out from 2FA. This is however, like leaving users into a simple choice: use Facebook by accepting privacy concerns, find another way to protect their information, or just ditch Facebook altogether.

The report from the universities' researchers reveals that Facebook is not as transparent as many people have thought it would be, especially after the numerous scandals if have embroiled into.

This is not the first time Facebook has been revealed to be less-than-ethical in dealing with sensitive data it has been trusted with. This apparent weakness is probably one of the driving force that let many young generation users down, making them to move away from Facebook.