Facebook Let a Personality Quiz Harvest 87 Million Profiles
One professor's app collected data on 300,000 people who took a quiz, and on 87 million people who never touched it.
In 2014, a Cambridge University researcher named Aleksandr Kogan built a personality-quiz app on Facebook's platform. Roughly 300,000 people took the quiz. Thanks to Facebook's permissions at the time, the app also quietly pulled data from those users' friends — scaling 300,000 willing participants into an estimated 87 million harvested profiles, most of them people who had never seen the quiz and never agreed to anything.
That data ended up with Cambridge Analytica, a political consulting firm that used it to build psychological profiles for targeted campaign advertising, including work for the 2016 Trump campaign. The Guardian and New York Times broke the story in March 2018, initially reporting 50 million affected profiles; Facebook itself revised the number up to 87 million weeks later.
Mark Zuckerberg testified before Congress over two days in April 2018, telling the Senate, "We didn't take a broad enough view of our responsibility, and that was a big mistake. It was my mistake, and I'm sorry." The apology did not come cheap: in 2019 the FTC imposed a record $5 billion penalty on Facebook, the largest privacy fine in U.S. history at the time. Cambridge Analytica itself declared bankruptcy amid the fallout.
The company had spent years insisting user data was safe on the platform. It turned out that "safe" had meant "safe from you looking at it yourself," not "safe from a stranger's quiz app quietly walking off with your friend list."
Filed from public reporting:
