533 million Facebook users’ phone numbers leaked on hacker forum

The mobile phone numbers and other personal information for approximately 533 million Facebook users worldwide has been leaked on a popular hacker forum for free.

The stolen data first surfaced on a hacking community in June 2020 when a member began selling the Facebook data to other members. What made this leak stand out was that it contained member information that can be scraped from public profiles and private mobile numbers associated with the accounts.

The sold data included 533,313,128 Facebook users, with information such as a member's mobile number, Facebook ID, name, gender, location, relationship status, occupation, date of birth, and email addresses.

From samples of the Facebook data seen by BleepingComputer, almost every user record contains a mobile phone number, a Facebook ID, a name, and the member's gender.

Below is a small sample of USA records showing the redacted mobile numbers starting with New York's 917 mobile area code.

According to Alon Gal, CTO of cybercrime intelligence firm Hudson Rock, it is believed that threat actors exploited in 2019 a now-patched vulnerability in Facebook's "Add Friend" feature that allowed them to gain access to member's phone numbers. 

It is unknown if this alleged vulnerability allowed the threat actor to retrieve all of the information in the leaked data or just the phone number, which was then combined with information scraped from public profiles.

After the initial sale of the data, which is believed to be for $30,000, another threat actor created a private Telegram bot that allowed other threat actors to pay to search through the Facebook data. 

Facebook data leak released for free

Today, this Facebook data leak has been released for free on the same hacker forum for eight site 'credits,' a form of currency on the hacker forum, equal to approximately $2.19.

While data breaches are initially sold in private sales for a high price, it is common for them to be sold for lower and lower prices until they are eventually released for free as a way of earning reputation within the hacker community.

"As is the case every time, people began to sell for cheaper and cheaper until it leaked for free," Gal told BleepingComputer in a conversation.

Included in the data leak are the phone numbers for three of Facebook's founders - Mark Zuckerberg, Chris Hughes, and Dustin Moskovitz, which are the 4th, 5th, and 6th members first registered on Facebook.

In response to our queries regarding the data leak, Facebook told BleepingComputer that this data is the same data as was harvested in 2019.

"This is old data that was previously reported on in 2019. We found and fixed this issue in August 2019," a Facebook spokeperson told BleepingComputer.

While the data may be from 2019, it is common for phone numbers and email addresses to remain the same over a period of many years, making this valuable to threat actors.

The top 20 geographic locations where members were exposed, as described by the threat actor, are listed below. These locations are likely what was entered by the Facebook member in their profile.

 A full list of locations and associated member counts can be found at the end of the article.

Location	Number of users
Egypt	44,823,547
Tunisia	39,526,412
Italy	35,677,323
USA	32,315,282
Saudi Arabia	28,804,686
France	19,848,559
Turkey	19,638,821
Morocco	18,939,198
Colombia	17,957,908
Iraq	17,116,398
Africa	14,323,766
Mexico	13,330,561
Malaysia	11,675,894
United Kingdom	11,522,328
Algeria	11,505,898
Spain	10,894,206
Russia	9,996,405
Sudan	9,464,772
Nigeria	9,000,131
Peru	8,075,317

Data can be used to conduct attacks

This release has been met with enthusiasm by other threat actors on the hacker forum as they can use it to conduct attacks on the people listed in the data leak. 

For example, threat actors can use email addresses for phishing attacks and mobile numbers for smishing (mobile text phishing) attacks. 

Threat actors can also use mobile numbers and leaked info to perform SIM swap attacks to steal multi-factor authentication codes sent via SMS.

It is advised that all Facebook users be wary of strange emails or texts requesting further information or telling you to click on enclosed links.

A full list of geographic locations, as shared by the threat actor, and the amount of exposed users per location can be seen below. On mobile, you can scroll the table left and right to see any cut off data.

 

Update 4/3/21 3:00 PM EST: Added leaked Facebook founders and that date of birth may be included in leaked data
Update 4/3/21 8:54 PM EST: Added statement from Facebook.
Update 4/4/21 11:12 AM EST: Added the full list of geographic users and amount of exposed users.