Over 4000 Android Apps Expose Users’ Data via Misconfigured Firebase Databases

The investigation, led by Bob Diachenko from Security Discovery
in partnership with Comparitech, is the result of an analysis of
15,735 Android apps, which comprise about 18 percent of all apps on
Google Play store.

“4.8 percent of mobile apps using Google Firebase to store user
data are not properly secured, allowing anyone to access databases
containing users’ personal information, access tokens, and other
data without a password or any other authentication,” Comparitech
said.
^[1]

Acquired by Google in 2014, Firebase is a popular mobile application
development platform that offers a variety of tools to help
third-party app developers build apps, securely store app data and
files, fix issues, and even engage with users via in-app messaging
features.

With the vulnerable apps in question — mostly spanning games,
education, entertainment, and business categories — installed 4.22
billion times by Android users, Comparitech said: “the chances are
high that an Android user’s privacy has been compromised by at
least one app.”

Given that Firebase is a cross-platform tool, the researchers
also warned that the misconfigurations are likely to impact iOS and
web apps as well.

The full contents of the database, spanning across 4,282 apps,
included:

• Email addresses: 7,000,000+
• Usernames: 4,400,000+
• Passwords: 1,000,000+
• Phone numbers: 5,300,000+
• Full names: 18,300,000+
• Chat messages: 6,800,000+
• GPS data: 6,200,000+
• IP addresses: 156,000+
• Street addresses: 560,000+

Diachenko found the exposed databases using known Firebase’s
REST API that’s used
to access data stored on unprotected instances, retrieved in JSON
format, by simply suffixing “/.json” to a database URL (e.g.
“https://~project_id~.firebaseio.com/.json”).

Complicating the matter further is the indexing of Firebase
database URLs by search engines such as Bing, which exposes the
vulnerable endpoints for anyone on the Internet. A Google search,
however, returns no results.

After Google was notified of the findings on April 22, the search
giant said it’s reaching out to affected developers to patch the
issues.

This is not the first time exposed Firebase databases have
leaked personal information. Researchers from mobile security firm
Appthority^[4]
found a similar case two years ago, resulting in the exposure of
100 million data records.

Leaving a database exposed without any authentication is an open
invite for bad actors. It’s therefore recommended that app
developers adhere to Firebase database
rules^[5] to secure data and
prevent unauthorized access.

Users, for their part, are urged to stick to only trusted apps
and be cautious about the information that’s shared with an
application.

^[2][3]