Shadow profiles are the biggest flaw in Facebook’s privacy defense

Called before Congress this week, Mark Zuckerberg tried to present Facebook's approach to user data as open and transparent. In question after question, he focused on the privacy options available to users and their ownership of all the data they share, and not everything was incorrect. Facebook has data because users share it (mainly). Users control that data and can review or delete it whenever they want (with some exceptions). And if you delete your account, (almost) all of that data will disappear from the Facebook servers within 90 days. None of that is false, but as the parentheses should tell you, it is incomplete, and by the second day of the hearings, members of Congress were beginning to understand.

The most powerful example came from Rep. Ben Luján (D-NM), who confronted Zuckerberg about the use of hidden profiles by the company, a term for the collection of non-user data with the that Zuckerberg was apparently not familiar.

"It has been admitted that data points are collected from users who are not from Facebook," Luján asked. "So my question is, does someone who does not have a Facebook account opt ​​for the involuntary collection of Facebook data?"

"Congressman, anyone can choose not to receive any type of ad collection, whether they use our services or not." Zuckerberg said. "But to prevent people from restricting public information, we need to know when someone is repeatedly trying to access our services."

"You have said that everyone controls your data, but you are collecting data about people who are not even Facebook users, who never signed a consent or privacy agreement and that you are collecting their data," continued Luján. "And you're directing people who do not have a Facebook page to sign up on Facebook to get their data."

In the exchange, Luján took advantage of a serious error in Zuckerberg's vision based on Facebook's consent, one that could have regulatory consequences in the coming months. The fact is that, even if you have never registered on Facebook, the company still has a general idea of ​​who you are, gathered through lists of loaded contacts, photos or other sources.

The collection of Facebook data about non-Facebook users opens up a world of questions about what data is and is not covered by Zuckerberg's vision of user consent and control. Zuckerberg said repeatedly that Facebook removes all data from your profile if you delete your account, but what about the hidden profile data that preceded your account? Zuckerberg also mentioned the possibility of downloading his Facebook data, but not only a user who does not belong to Facebook does not have access to that information, the download tool omits the data that Facebook collects and uses clearly, whether they are Pixel data analyzed from Facebook or location data extracted. from a telephone

The most concrete example of an alternative profile comes from the People You May Know service of Facebook, studied in detail by Kashmir Hill in Gizmodo . Even if you have never registered on Facebook, you have appeared on the contact list of people who did. When users connect their email account or text message data with Facebook, countless users are not swept. Instead of discarding their information, Facebook keeps unrelated user data in something that Hill calls an alternative profile: a reliable information bank that is kept in reserve, so that, if ever is recorded On Facebook, the company knows exactly who to recommend as friends.

If that were all, it would be easy enough to get away, but the hidden profiles have become a substitute for all the data that are not part of the official profile of a person. Facebook says that when you delete your account, all your data disappears from the company's servers within 90 days, but it's hard to believe that it applies to the hidden profile data, which exists even without an official profile. Today, Zuckerberg assured Congress that Facebook's data download tool includes all the information of a given user, but it lacks a large part of the web-based tracking done by Facebook through the Insert button, showing only the categories of interest that are created as a result of that data. How can we be sure that similar data is not collected about non-users or that they do not remain associated with them after deleting their account?

Rep. Kurt Schrader (D-OR) tried to get a response from Zuckerberg about the extent of Facebook tracking of users off the platform, but the response was ambiguous.

"According to my testimony based on the testimony here today, even after that" When they left Facebook, they still have the ability to follow my interactions on the web, "Schrader asked Zuckerberg.

" You have control over what we do for announcements and collections of information based on that, "Zuckerberg replied." As for security, there may be specific aspects about how you use Facebook, even if you have not started session, we do a follow-up to make sure you're not abusing the systems. "

This question zone is particularly complicated for Facebook because, as Luján pointed out, all Facebook controls have a person who has a profile of Facebook You can not change your ad settings or download your information unless you are a Facebook user, even though we know that the company still contains information related to you. That catch-22 can soon cause problems in Europe, where the GDPR requires data portability for all citizens, not just Facebook users.

Meanwhile, Facebook's data protection tools mostly serve to distract users from more aggressive data collection behind the scenes. That point was taken home by a heated speech by Representative Debbie Dingell (D-MI) towards the end of the hearing, leading Zuckerberg to the task for lack of information.

"As CEO, I did not know some key facts," Dingell told Zuckerberg. "You did not know what a hidden profile was, you did not know how many applications you need to audit, you did not know how many other companies have been sold by Cambridge Analytica … You do not even know the different types of information that Facebook collects from its users."

"This is what I know," Dingell continued. "You have crawlers all over the web." Virtually all websites, we all see "Like" or "Like" buttons on Facebook, and with Facebook Pixel, people may not even see the Facebook logo. It matters if you have a Facebook account, through these tools, Facebook can collect information from all of us. "