Most malware requires some form of active user interaction in order to infect a device — a click on a link in a phishing email, or the installation of software from an unverified source.
But a new type of attack, dubbed Cloak and Dagger, can basically take over your Android phone without your (conscious) help. Worse, no major version of Android is safe at this time.
Described by a team of researchers from the University of California and the Georgia Institute of Technology, Cloak and Dagger relies on the way Android UI handles certain permissions.
f an app is downloaded from Google’s Play Store, researchers claim, it is automatically granted the SYSTEM_ALERT_WINDOW permission, aka “draw on top.” You’ve likely seen this permission in action — it’s used by Facebook’s chat heads, which float over other content on your screen.
This can be used to hijack the user’s clicks and lure her into giving the app another permission, called BIND_ACCESSIBILITY_SERVICE or a11y, which can be used for stealing your passwords and pins, for example.
A hacker that combines both these vulnerabilities could silently install a “God-mode” app with all permissions enabled, including access to your messages and calls.
Even though a lot of this is intended behavior and not an actual exploit, it can definitely be used to take over someone’s device. The researchers claim they tested it on 20 human subjects, none of which had realized what was going on.
The one thing that protects users right now is the fact that to do all this, the malicious app must be downloaded from Google’s official Play Store, meaning that it has to pass Google’s security checks. But from past examples we know it’s definitely possible for malicious hackers to slip in a malware-infested app into Play Store.
“It is trivial to get such an app accepted on the Google Play Store.”
“A quick experiment shows that it is trivial to get such an app accepted on the Google Play Store,” the researchers claim. “We submitted an app requiring these two permissions and containing a non-obfuscated functionality to download and execute arbitrary code (attempting to simulate a clearly-malicious behavior): this app got approved after just a few hours (and it is still available on the Google Play Store),” they wrote.
While Google has partially fixed the issue in the latest version of Android (7.1.2), the researchers claim it’s still fully possible to take advantage of the vulnerabilities described above. According to the researchers, these aren’t “simple bugs” but “design-related issues,” meaning it will take more time to fix them; moreover, Google considers some of these issues as features, and does not currently plan to fix them.
To protect their devices, the only thing users can do right now is check which apps have access to the “draw on top” and a11y permissions. The steps to do this vary in different versions of Android; they are listed here.
Mashable has contacted Google about these vulnerabilities and will update the article when we hear from them.