According to Trend Micro's Q2 2013 Security Roundup Report, the number of malicious and high-risk Android apps surged from 509,000 in the first quarter of 2013 to 718,000 in the second quarter.

The company expects the number of malicious Android apps to exceed one million by the end of 2013 -- but according to the NPD Group, only 30 percent of all Android smartphones and tablets in the U.S. have any type of security app installed.

"Due to the fractured nature of the Android network, it is very difficult for patches to reach all users in an effective timeframe," Trend Micro vice president for technology and solutions JD Sherry said in a statement. "In some cases, users will never get patches as vendors leave their customers at risk of attack. Until we have the same urgency to protect mobile devices as we have for protecting PCs, this very real threat will continue to grow rapidly."

"At the rate this malware is accelerating -- almost exponentially -- we appear to be reaching a critical mass," Sherry added. "To fight this, Android users need to take great care when using their devices and take the simple, but effective, step of adding security software to all mobile devices."