Google has been battling malicious apps throughout the year, most recently malware was packed in an app called “Lovely Wallpaper”. This new strain of malware was titled “ExpensiveWall”, and hid in the wallpaper application while stealthily racking up premium SMS fees. It further propagates by sending out text messages on your behalf, inviting others to download the same compromised app.

The malware was compressed and encrypted within an SDK used by roughly 50 different apps without being detected by Google. It is still undetermined how much money was actually generated from this SMS scam.

How it Works

ExpensiveWall uses JavaScript along with the enhanced permissions on the infected device to orchestrate the attack. It creates an interactive interface between the app downloaded and a web interface called WebView. This action allows the malware to run in-app controls through this WebView interface including but not limited to sending SMS messages and registering the user devices to premium paid services without notice. The only way for this malware to work is if the user allows full SMS control and communication to its command and control server. This communication will send data about the infected device including IP address, MAC address and Geolocation data.

What can you do to Prevent it?

Simply put, be aware of what permissions you are granting applications when you install them. The fact that millions of other people have downloaded an app and given it good reviews does not mean that it is safe. This app is clear cut proof to that effect. Below are some things that should throw up red flags when installing an application.

• Make calls or texts on your behalf
• Receive SMS
• Read contacts or sensitive device logs
• Communicate with other applications
• Control/disable the keyboard
• Kill processes
• Write secure settings
• Have the ability to authenticate accounts
• Create system services
• Control in-app billing/services
• Accessing GPS data

Some of these may actually be needed in order for certain applications to function properly, but be cautious. If you don’t think that flashlight app needs to make calls on your behalf, don’t install it. Lastly, a solid antivirus with web-browsing and application scanning is a necessity for your mobile device.