The Android platform expanded its dominance in the U.S. smartphone market during Q4 of 2011, according to the latest ComScore report. Apple may have boosted its share of the mobile handset market with the release of the iPhone 4S, but Android’s still the clear winner in terms of OS use, powering 47.3 percent of surveyed subscribers. That’s up from 44.8 percent last year, growing by slightly more percentage points than Apple’s increase to 29.6 percent from 27.4 percent.

Google gets a bouncer to keep malware out

The rising popularity of Android’s open platform makes it the prime target for malware, and Google’s had quite a time managing mobile threats and consumer expectations around device security. Taking matters into their own hands, Google unveiled an automated system to scan Android apps for potential malware or unauthorized behavior. Codenamed Bouncer, the scanner has been a long time coming, though Hiroshi Lockheimer, vice-president of engineering for Android, said Bouncer’s been in action for months, running unnoticed in the background.

Bouncer scans apps before they even hit the Android Market, looking for known malware including spyware and Trojan horses, as well as behavior that matches malicious apps that have previously been identified. The scanner also features a simulator that runs each app as it if were on an actual Android device, observing the app for “hidden behavior” and marking it for review if needed. Google already had the ability to re-check published apps in the Market, but Bouncer adds more analytics to the process.

More Market malware?

That historic data analysis has been a necessary tool for mobile security providers like Lookout, enabling them to go so far as to predict how and when malware could affect Android users. And the timing for Google’s Bouncer scanner couldn’t be better, as Symantec just uncovered another malicious Trojan on the Android platform. Dubbed Android.Opfake, this low-risk Trojan sends SMS texts to premium-rate numbers, racking up some serious charges on your phone bill.