Beware fake Instagram app on Android

Enjoy perusing for Android apps outside the confines of Google Play? Be sure to avoid any apps touting the photo-sharing service Instagram.

The blog Naked Security from company Sophos is warning Android users about a fake Instagram app that's popped up following its debut on the Google operating system.

Instead of an app with fun filters to upgrade images, users will get malware. Here's how Sophos describes it:

"In our tests, the app didn't do a very good job of emulating the genuine Instagram app, but that may be because it failed to find the correct network operator. Because this is a malicious app that seems to be relying on the sending of background SMS messages to earn its creators revenue."

Sophos stresses this app is available outside Google Play, so if you're not venturing out in search of Android apps, you should be fine. A search for Instagram on Google Play only turns up the official -- and safe -- app.

This discovery arrives as more mobile devices become targets for malicious software. Last year, the Associated Press reported attackers are hard at work developing ways to infect smartphones.

"As more and more people use phones and keep data on phones, and PCs aren't as relevant, the bad guys are going to follow that," security expert Charlie Miller told the AP.

It's been a huge month for Instagram, which might explain why this malicious version of the popular app has surfaced. It topped 5 million downloads within a week of landing on Google Play, and got scooped up by Facebook for $1 billion.