­Android "Battery Doctor" tops the list of smartphone malware threats in the UK, according to a nine-month study of Android malware and aggressive adware by anti-virus software developer, Bitdefender.

Posing as a battery optimisation app, the Android.Trojan.FakeDoc family topped the list of malware threats from January to September 2012. The Trojan intercepts Gmail messages and broadcasts them to an attacker-controlled server, along with geo-location data and carrier name.

Analysing the first nine-months for malware and adware evolution, Bitdefender has identified two peaks. The first peak was in April and May, when Android.Trojan.FakeDoc.A accounted for 76 percent of the overall malware detected; the second peak took place in September, when the Android.Adware.Plankton.A increased to 52 percent of the overall malware detected.

As a reference, Bitdefender detects the "Slot Machine" Google Play game as having aggressive adware, noting it is malicious. With more than 500,000 installs, the game is popular both in the UK and worldwide.

The dominant Android.Adware.Mulad aggressive adware family dropped to an all-time low in September, reaching a 5.59 percent detection rate. However, September was the first time this year in the UK when the total adware detection rate surpassed that of malware, clocking in at 59.52 percent.

Bitdefender classifies aggressive adware as apps that can change the default search engine, place additional shortcuts on your home screen that link to promotional content, display more popups that regular apps, etc.

"The mobile apps industry is facing a period of rapid evolution towards radically more aggressive and commercially-oriented attacks. Smartphones, our 24 hour connection to the internet, will become the first target for those looking to steal our banking credentials, credit card numbers and other personal information. The recently identified problem on how tablets and smartphone apps implement the security protocol is just the first signal of a new type of attacks towards mobile devices," said Alexandru Balan, Chief Security Researcher at Bitdefender.