After a massive leak of database containing names and phone numbers of more than 267 million users online, Facebook on Thursday said it is investigating the matter. The database was made available for download last week on an online hacker forum that apparently belonged to a crime group, according to a blog post on the website Comparitech.

“We are looking into this issue, but believe this is likely information obtained before changes we made in the past few years to better protect people’s information,” a Facebook spokesperson told news ageny AFP.

Comparitech said that security researcher Bob Diachenko spotted the database, which was openly accessible and contained Facebook users’ names, user IDs and phone numbers.

The discovery was reported and the database was no longer available by Thursday, according to Comparitech. Revelation of the exposed data comes as the social network strives to rebuild trust and alleviate concerns over protection of people’s information.

US regulators earlier this month said that British consultancy Cambridge Analytica, at the center of a massive scandal involving Facebook data hijacking, deceived the social network’s users about how it collected and handled their personal information.