Using a Facebook feature that was designed to help people find friends using contact lists easily, the company on Tuesday said that hackers “scraped” personal data of over half a billion users in 2019. Facebook said that information of over 530 million users was shared over a weekend at a hacker forum, an incident that prompted the platform to explain what happened, calling on people to stay vigil about privacy settings. 

Facebook product management director Mike Clark in a post said, “It is important to understand that malicious actors obtained this data not through hacking our systems but by scraping it from our platform prior to September 2019.”

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Clark said that the incident was another example of the “ongoing, adversarial relationship technology companies have with fraudsters”, who are trying to break Facebook’s policies “to scrape internet services.”

Through scraping, automated software gathers information that has been shared publicly online.

Hackers had accessed phone numbers, birth dates, and email addresses, reports AFP quoting US media, and added that some of the data appeared to be current.

Facebook said that the stolen did not include passwords or financial data or passwords.

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“All 533,000,000 Facebook records were just leaked for free,” Facebook’s chief technology officer at the Hudson Rock cybercrime intelligence firm, Alon Gal said on Saturday via Twitter. 

Clark urged members of the social network to check their privacy settings to control what information can be seen publicly, and to tighten account security with two-factor authentication.

This is not the first time leaks or use of data from the world’s largest social network — with nearly two billion users — has embroiled Facebook in controversy.

In 2016, a scandal around Cambridge Analytica, a British consulting firm that used the personal data of millions of Facebook users to target political ads, cast a shadow over the social network and its handling of private information.