Updated The first text message-based Trojan to infect smartphones running Google's Android operating system has been detected in the wild.

Trojan-SMS.AndroidOS.FakePlayer-A poses as a harmless media player application and has already infected a number of mobile devices, Russian security firm Kaspersky Lab warns. Prospective marks are prompted to install a "media player file" of just over 13 KB with the standard Android .APK extension.

Once installed, the Trojan begins sending SMS messages to premium-rate numbers without the owner’s knowledge or consent, as explained in a technical write-up by computer security researcher Jon Oberheide here. Victims wind up with a huge bill while the cybercrooks behind the scheme earn a slice of the income. The scam has only affected Android smartphone users in Russia.

In a statement, Google said its existing permission controls guard against this type of scam, which only exists for applications published outside the Android Marketplace.

Our application permissions model protects against this type of threat. When installing an application, users see a screen that explains clearly what information and system resources the application has permission to access, such as a user's phone number or sending an SMS. Users must explicitly approve this access in order to continue with the installation, and they may uninstall applications at any time. We consistently advise users to only install apps they trust. In particular, users should exercise caution when installing applications outside of Android Market.

There have been isolated cases of devices running Android getting infected with spyware since last year, but this is the first occasion that an SMS-spewing Trojan, common in the world of mobile malware, has affected devices running Google's operating system.

Denis Maslennikov, mobile research group manager at Kaspersky Lab, said the success of the Android platform in the marketplace has triggered increased interest from virus writers. The Russian security firm plans to respond to the increased threat with a new mobile security product, Kaspersky Mobile Security for Android, in early 2011.

Users are advised to pay close attention to the services that an application requests access to during installation. If a user agrees to permit an application to access premium rate service during installation, the smartphone may then be able to make calls and send SMSs without further authorisation.

In related news, BBC journalists created a mobile application with hidden spy functionality as part of an exercise designed to demonstrate how straightforward it has become to create a malicious application for a smartphone. The application was put together using standard components from software toolkits that developers use to create programs for handsets, an approach that might make the malware harder to detect.

The malware was not released into the wild or placed in an app store so no hacking of innocent PCs or smartphones was involved. Thus the exercise was far less ethically fraught than BBC Click's botnet hire spamming jape last year.

Application security firm Veracode helped BBC hack Mark Ward build the basic game of noughts-and-crosses with hidden backdoor spying functionality. "The spyware took up about 250 lines of the 1500 making up the entire program," Ward reports. ®