MOBILE SECURITY FIRM Lookout has warned that almost seven percent of Android apps in the Google Play store contain adware.
The firm advised in a blog post that "questionable mobile advertising practices", such as adware, is "the number one threat out of all potentially harmful content that people can encounter on their mobile phones", and can get in the way of user privacy and operating experience.
In the past year, Lookout said that over one million US Android users have downloaded adware and approximately 6.5 percent of apps in the Google Play store contain it.
Across the different categories of apps available for download from the store, lookout said "personalisation" apps were the most likely to include adware, making up 26 percent of the apps found. Next popular was "gaming", at nine percent, followed by "music & audio" at eight percent.
"[Adware is] capturing personal information such as email, location, address list, without proper notification and modifying phone settings and desktops without consent," the firm said.
"This affects millions of people and, if not addressed by the industry itself, is likely to result in consumer backlash and possibly regulation."
The claim appears in Lookout's study of adware practices in mobile apps, which deals with research into suspicious ad behaviours. The mobile security company came to its conclusions by sampling a random selection of over 200,000 Android apps from Google Play and then running its scanning engine over the entire set and classifying them as containing adware or not.
Earlier this year, Lookout warned that a more dangerous form of the once widespread Android malware threat "Notcompatible" had resurfaced, now using email spam distribution to dupe people.
The US security company said that it had seen a "staggering increase" in detections of the Notcompatible malware, which was first reported in May 2012 as a remote proxy threat distributed by hacked websites.
That was the first time the industry saw hacked websites being used to specifically target mobile devices rather than PCs. However, now it seems that the threat is back, and more hazardous than before, using email spam to infect Android devices. µ