Facebook users will soon know if their data was shared with Cambridge Analytica

Anyone wondering if their private Facebook data might have been swept up in the Cambridge Analytica scandal will soon get their first clues.

Starting Monday, all 2.2 billion Facebook users will receive a notice on their feeds, titled "Protecting Your Information," with a link to see what apps they use and what information they have shared with those apps. If they want, they can shut off apps individually or turn off third-party access to their apps completely.

In addition, the 87 million users who might have had their data shared with Cambridge Analytica will get a more detailed message informing them of this. Facebook says most of the affected users (more than 70 million) are in the U.S., though there are over a million each in the Philippines, Indonesia and the U.K.

Reeling from its worst privacy crisis in history allegations that Cambridge Analytica may have used ill-gotten user data to try to influence elections Facebook is in full damage-control mode, with CEO Mark Zuckerberg acknowledging he's made a "huge mistake" in failing to take a broad enough view of what Facebook's responsibility is in the world. He's set to testify before Congress next week.

Cambridge Analytica whistleblower Christopher Wylie previously estimated that more than 50 million people were compromised by a personality quiz that collected data from users and their friends.

That Facebook appcalled This is Your Digital Lifewas a personality quiz created in 2014 by an academic researcher named Aleksander Kogan, who paid about 270,000 people to take it. The app vacuumed up not just the data of the people who took it, but also thanks to Facebook's loose restrictions data from their friends, too, including details that they hadn't intended to share publicly.

Facebook later limited the data that apps can access, but it was too late in this case.

Zuckerberg said Facebook came up with the 87 million figure by calculating the maximum number of friends that users could have had while Kogan's app was collecting data. The company doesn't have logs going back that far, he said, so it can't know exactly how many people may have been affected.

Cambridge Analytica said in a statement Wednesday that it had data for only 30 million people.

The company is facing a global backlash over the improper data-sharing scandal. Hearings over the issue are scheduled in the U.S., and the European Union is considering what actions to take against the company.

Facebook toaudit data breach

Facebook's chief operating officer SherylSandbergsaid the company should have conducted an audit after learning that a political consultancy improperly accessed user data nearly three years ago. The executive told NBC's Today show that, at the time, Facebook received legal assurances that Cambridge Analytica had deleted the improperly obtained information.

"What we didn't do is the next step of an audit and we're trying to that now," she said.

The audit of Cambridge Analytica is on hold, in deference to a U.K. investigation. But Facebook has been conducting a broader review of its own practices and how other third-party apps use data.

In addition, Facebook announced on Friday that it will require advertisers who want to run not just political ads, but also so called "issue ads" which may not endorse specific candidates or parties but discuss political topics to be verified.

Facebook is trying to strengthen its system ahead of this year's U.S. midterm elections as well as upcoming elections around the world. Facebook has already required political ads to verify who is paying for them and where the advertiser is located. The issue ads requirement is new.

Facebook will also require the administrators of pages with a "large number" of followers to also be verified. The company did not say what this number would be. The move is intended to clamp down on fake pages and accounts that were used to disrupt the 2016 presidential elections in the U.S.

Advertisers will be verified

Facebook said page administrators and advertisers will be verified by being asked to provide a government-issued ID. To verify addresses, it will mail a postcard with a unique code that the recipient can then enter into Facebook. This is similar to how Airbnb and other services verify addresses.

Sandberg also told NBC that if users were able to opt out of being shown ads, "at the highest level, that would be a paid product." This does not mean the company is planning to let users do this. Zuckerberg has made similar statements in the past, but has added that Facebook remains committed to offering a free service paid for by advertising.

Facebook users can opt out of seeing targeted ads, but can't shut off ads altogether. Neither can they opt entirely out of Facebook's data collection.

Sandberggave several interviews this week asZuckerbergprepares to testify before Congress.The issue of elections meddling is almost certain to come up. Facebook is also facing an investigation by the Federal Trade Commission in what's become the worst privacy crisis in its 14-year history.

It started with revelations that Cambridge Analytica improperly accessed the private information of tens of millions of users to try to influence elections around the world. Over the past three weeks, the scandal has continued to spiral. Facebook executives took nearly five days to respond to the Cambridge Analytica reports.

Also, some users who logged in to Facebook through Android devices discovered that Facebook had been collecting information about phone calls they made and text messages they sent. Facebook also acknowledged this week that nearly all of its 2.2 billion users may have had their public data scraped by "malicious actors" it did not name.