Malicious apps contained in the Google Play store have grown 388 percent between 2011 and 2013, according to a report from RiskIQ, an Internet security services company. At the same time, the number of malicious apps that Google has removed annually dropped to 23 percent in 2013, down from 60 percent in 2011.

Using RiskIQ for Mobile to continuously monitor, scan and interact with mobile apps in the Google Play store, the company identified Android apps as malicious if they contained spyware or Trojans that met certain criteria, such as collecting and sending GPS coordinates, contact lists and the like to third parties, or sending SMS messages to premium-rate numbers and/or subscribing infected phones to premium services. The spyware- or Trojan-infected apps were also considered malicious if they recorded phone calls, commandeered infected phones or downloaded additional malware onto those phones.

“For the past couple of years we have been seeing the pace of growth accelerate for malicious, copycat and low quality apps designed to defraud companies and their consumers,” RiskIQ CEO Elias Manousus told SCMagazine.com in an email correspondence. “More than 50 percent of these apps are linked to ad frameworks that are capturing end-user data and reselling it. Attackers are continuously improving their ability to elude detection by traditional anti-virus tools, so the drop in malicious apps removed is not that surprising.”

To better guard against malware, Manousus said, “what’s needed is the ability to open apps and detect abnormal, malicious behaviors.”

The company found that 12 percent of the apps in the Google Play store were malicious, up from 2.7 percent in 2011. While sports, media/audio.video, education/books and entertainment all ranked among the top five malicious app categories, personalization apps led the category. RiskIQ research showed that Talking Angela was the most downloaded malicious app in 2013.

“Google Play uses a more open model than the Apple app store, so this makes Android apps more vulnerable to attack than iOS apps. Google Play, however, is generally more secure than the other app stores,” Manousos said.