Not all the security and privacy threats posed by mobile apps are unintentional: Many of them incorporate third-party ad modules that track user behavior. "We did a test of the top 400 apps and found there's a huge zoo of trackers out there. All those companies can get information on you if you used the apps," said Jens Heider, head of Fraunhofer Institute's mobile security test lab.
The Appicaptor service provides regular scans of iOS, Android, Windows Phone and BlackBerry apps to warn when they include such functions. Businesses can subscribe to a report about the security of up to 100 apps for €1,500 (US$2,100) per month, including the purchase cost of up to €5 per app. For €5,000 per month the service will report weekly on how up to 500 apps comply with a security policy defined by the customer, Heider said.
At the Fraunhofer Institute for Applied and Integrated Security another team has developed App-Ray, a security scanner for Android apps that can be used by businesses policing their bring-your-own-device security policy, or by developers curious about what unexpected or unwanted functions the third-party modules they use may have brought with them.
"We find stuff that is not problematic per se, but may be a problem in a company environment," said Dennis Titze, one of the researchers involved. For example, an app that can record audio may not in itself be bad — Whatsapp can record 10-second clips to send as messages, for instance — but combined with the ability to access the calendar and activate the microphone when the phone's owner is attending a meeting, it may become a security risk, he said.
App-Ray also detects threats inherent in what the app doesn't do, rather than what it does, such as insecure SSL certificate checking: "We look at an app's byte code to see if it implements its own trust manager, [rather than the standard APIs] and whether it looks like this does something. Many apps have a certificate check function that doesn't have any code in it, it just returns."
App-Ray is ready for commercial use, and the lab is looking at two pricing models, Titze said. An on-premises version, available as a virtual machine image, would cost somewhere between €10,000 and €100,000 a year, allowing businesses to test as many apps as they wish with no one else aware of which applications they are concerned about. This could be an advantage for a developer, for instance, looking for security risks in new versions of its apps before uploading them to an online market. A hosted version would cost between €100 and €1000 a month, he said.
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