Researchers at Kaspersky Lab recently came across a new Trojan designed to target Android smartphones. The malware, delivered via the Google Play store, is capable of rooting devices and it leverages some new techniques to achieve its goal.
The Trojan, dubbed “Dvmap” by Kaspersky, was uploaded to Google Play disguised as various apps, such as a simple puzzle game. The security firm said the malicious apps were downloaded from the official Android app store more than 50,000 times before being removed by Google.
It’s not uncommon for malware to make its way into Google Play. In the case of Dvmap, cybercriminals uploaded a clean application at the end of March and then, on five separate occasions between April 18 and May 15, they pushed malicious updates that were available for only a short period of time.
By keeping the malicious version on Google Play only for a short amount of time – the clean version would typically be re-uploaded on the same day – the attackers managed to evade detection by Google’s security systems.
Once it infects a device, the malware, which works on both 32-bit and 64-bit versions of Android, uses a local root exploit pack to obtain root privileges. If the smartphone has been successfully rooter, several modules are installed on the system.
It’s not uncommon for rooting malware to install modules on the targeted device, but Dvmap has another trick up its sleeve. The Trojan, whose code includes comments written in Chinese, also injects malicious code into system runtime libraries, and experts believe it’s the first piece of Android malware to do this.
The code injection takes place in the main phase of the attack, when the malware patches one of two runtime libraries – either libdvm.so or libandroid_runtime.so, depending on the version of Android present.
Dvmap replaces legitimate code with malicious code in order to execute its modules. However, this can also cause some legitimate apps to crash or stop functioning properly.
The malicious code executes a file that turns off the Verify Apps feature in Android to allow the installation of apps from third-party stores. It can also provide Device Administrator rights to an installed app whose purpose is to download other files.
The command and control (C&C) server did not send any files during Kaspersky’s tests so it’s unclear what types of files have been delivered, but researchers believe it’s either other malware or adware.
Judging by the fact that some of the techniques used by Dvmap can break infected devices, experts believe the cybercriminals are still testing the malware. However, given the large number of users who have already downloaded it from Google Play, they have plenty of devices to perform tests on.
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