Sunday, April 21, 2013

2013: The Year of the Facebook Mobile Attack?

Facebook has been pushing - if you don't update, you'll receive notifications in your newsfeed - a new version of the Facebook app for Android. I've reluctantly upgraded the version on my Nexus 7, but I'm holding off installing it on my phone. At this point, I'm not sure the increased risk is worth it.

"What risk?", I hear you ask. There's a potential exposure in the new Facebook app; the app requires somewhat looser permissions than the previous version, including - wait for it - the ability to directly call phone numbers. Big red flag here, Facebook. The major form of malware seen to date on Android phones has been apps that use this permission to call premium-rate international numbers, running up a huge phone bill for the victim and delivering a nice profit for the attacker.

Properties required by the Facebook app for Android -
notice "direct call phone numers"

The need to make phone calls arises from the introduction of the new "Facebook Home" - an app which takes over the home screen of a phone to present a Facebook-centric experience - as well as Facebook Messenger, which integrates Facebook messaging with SMS as well as supporting voice messaging. It's not clear to me why the main Facebook app, which does not support these functions, should also require access to the phone functionality, not to mention the ability to record audio, download files without notification, read your contacts and many other privacy-invading permissions.

At the same time Facebook has been a terrific vector for the spread of malware on the PC, sometimes in the form of infected videos or apps, as well as privacy-invading apps which harvest your profile, contacts or other information or download files.

The message: expect this to spread rapidly to mobile devices. Facebook now exposes a relatively large attack surface, and an attacker who can compromise the Facebook app on Android can use its permissions in a range of creative ways.

2013: the year of the Facebook mobile attack? I hope not, but it looks likely to me.
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