533 million Facebook users' phone numbers and personal data leaked online

Phone numbers and personal information of over 533 million Facebook users from 106 countries including Bangladesh, were leaked online by a user on a low-level hacking platform.

The information of these users from 106 countries, include over 32 million records for US users, 11 million for UK users, and 6 million for Indian users, and over 3.8 million for Bangladeshi users, reports the Insider.

User phone numbers, Facebook IDs, full names, addresses, birthdates, profiles, and, in some cases, email addresses are all included in the revealed data.

Insider examined a sample of the leaked data and confirmed some records by cross-referencing identified Facebook users' phone numbers with the data set's IDs. 

Records were also double-checked by putting email addresses from the Facebook password reset data set to the test, which can be used to expose a user's phone number in part.

According to Alon Gal, CTO of cybercrime intelligence company Hudson Rock, who first discovered the leaked data on Saturday, the data may provide useful information to cybercriminals who use people's personal information to impersonate them or scam them into handing over login credentials.

"A database of that size containing the private information such as phone numbers of a lot of Facebook's users would certainly lead to bad actors taking advantage of the data to perform social engineering attacks [or] hacking attempts," Gal told Insider.

Facebook did not immediately respond to multiple requests for comment.

Gal first discovered the leaked data in January when a user in the same hacking forum advertised an automated bot that could provide phone numbers for hundreds of millions of Facebook users in exchange for a price. Motherboard reported on that bot's existence at the time and verified that the data was legitimate.

Now, the entire dataset has been posted on the hacking forum for free, making it widely available to anyone with rudimentary data skills.

It's not the first time that a huge number of Facebook users' phone numbers have been found exposed online. A vulnerability that was uncovered in 2019 allowed millions of people's phone numbers to be scraped from Facebook's servers in violation of its terms of service. Facebook said that vulnerability was patched in August 2019. 

Facebook previously vowed to crack down on mass data-scraping after Cambridge Analytica scraped the data of 80 million users in violation of Facebook's terms of service to target voters with political ads in the 2016 election.

Gal said that, from a security standpoint, there's not much Facebook can do to help users affected by the breach since their data is already out in the open — but he added that Facebook could notify users so they could remain vigilant for possible phishing schemes or fraud using their personal data.

"Individuals signing up to a reputable company like Facebook are trusting them with their data and Facebook [is] supposed to treat the data with utmost respect," Gal said. "Users having their personal information leaked is a huge breach of trust and should be handled accordingly."