You need an Android smartphone BYOD policy

Here is another mass download of a malware infected Android app:

SpinOk Android malware found in more apps with 30 million installs (bleepingcomputer.com)

Please have a look at this:

Scanning for Apple iPhone iOS malware

You need a bring-your-own-device policy for your phones. This policy should also include to company owned devices.

Further Reading

Android and Smartphone Issues on Smart Thinking Solutions