Reporters from The New York Times and The Observer of London told Facebook that Cambridge had retained copies of private data for about 50 million Facebook users. Facebook says Cambridge promised in 2015 that the data would be deleted.
Cambridge Analytica is an offshoot of SCL Group, a government and military contractor that says it works on everything from food security research to counter-narcotics to political campaigns.
From 2014, Cambridge Analytica obtained data on 50 million Facebook users via means that deceived both the users and Facebook. The data was harvested by an application developed by a British academic, Aleksandr Kogan. Kogan built a Facebook app that was a quiz.
Some 270,000 people downloaded the application and logged in with their Facebook credentials, according to Facebook. The application gathered their data and data about their friends, and then Mr. Kogan passed the data to Cambridge Analytica, according to both Cambridge Analytica and Facebook.
Cambridge Analytica said on March 17 that it did not initially know Mr. Kogan violated Facebook’s terms, and that it deleted the data once it found out in 2015.
The scandal has attracted broad public interest because Cambridge did millions of dollars in political consulting work for Donald Trump’s presidential campaign. Some reports have portrayed the firm as the masterminds behind Trump’s election victory—and the stolen Facebook data as a key part of Trump’s digital strategy.