The malware in question is an SMS-sending Android Trojan dubbed "FakeInst", and was first spotted in February 2013 targeting Russian users.
Variants of it have been doing rounds ever since, and the malware has later been modified to target users in 65 additional countries around the world, including the US. Still, most victims are located in Russia, Kazakhstan, Canada and Poland.
The Trojan disguises itself as an application for watching porn videos, and prompts users to agree to send a text message to purchase paid content.
An affermative response to that question makes the app visit a free-access website that is, as far as I can tell, some sort of online community.
In the meantime and in the background, the Trojan decrypts a configuration file, finds in it premium-rate numbers that correspond to the country the mobile phone is registered in (i.e. the mobile country code), and starts sending out costly messages.
"As well as sending unauthorized text messages that cost around $2 each, the Trojan can send an SMS from an infected device with a preset text to a number specified in a C&C command, and intercept incoming messages," shared Roman Unuchek, Senior Malware Analyst at Kaspersky Lab. "The Trojan can do various things with incoming messages – steal all of them, delete them, or even respond to them."
The researchers believe that the Trojan was created by Russian-speaking cybercriminals, who have apparently built up sufficient resources to expand their illegal business on a global scale.