Pierluigi Paganini
November 22, 2015
Android is once again in the storm, threat actors can install any malicious third-party app on mobile devices remotely even if the users explicitly refuse it.
Security experts at mobile security firm Lookout have spotted Trojanized adware families that implement the ability to automatically install any mobile app on the devices by exploiting the Android accessibility features.
These families root the infected device after being installed and gain persistence by embedding their code in the system partition. The root access allows attackers to gain unrestricted access to the mobile devices.
“Last week we told you about three trojanized adware families: Shuanet, ShiftyBug, and Shedun. These families root the victim’s device after being installed and then embed themselves in the system partition in order to persist, even after factory reset, becoming nearly impossible to remove. We call it “trojanized adware,” because the end goal of this malware is to install secondary applications and serve aggressive advertising.” reads the blog post published by
The malware researchers highlighted the capabilities of the Shedun adware family that seem to be out of the ordinary because it doesn’t exploit any vulnerability to hijack an Android device, instead it relies on the service’s legitimate functionality.
During the installation, mobile apps from the Shedun adware family tricks users into granting them access to the Android Accessibility Service, this means they will be able to read the text on the phone screen, determine an app installation prompt, scroll through the permission list and press the install button on the behalf of the user.
“Lookout observed Shedun abusing the Android Accessibility Service for its malicious means. Using the accessibility service toolset in the delivery of malware is pretty uncommon, so we took a deeper look.” states the post. “By gaining the permission to use the accessibility service, Shedun is able to read the text that appears on screen, determine if an application installation prompt is shown, scroll through the permission list, and finally, press the install button without any physical interaction from the user.”
The following video shows apps from the Shedun adware family gaining accessibility service privileges.
In this second video Shedun automatically install a Shedun automatically install a trojanized app that masquerades itself as an official app available in Google Play Store and then is pushed to third-party markets.Shedun automatically install a Shedun automatically install a trojanized app that masquerades itself as an official app available in Google Play Store and then is pushed to third-party markets.
It is important to note that the Android Accessibility Service is also used by legitimate applications, users are advised not to install applications from third-party app markets.
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(Security Affairs – Android Accessibility Service, Shedun)
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