Aggressive adware causes problems for Android tablets and phones

Aggressive adverts in free apps for Android devices are pushing users through their download thresholds, draining battery life and changing settings without permission, security firm Bitdefender has warned.

Embedded advertising is an integral part of the many free apps available for Android smartphones and tablets, and is necessary to generate income for the developers.

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But Catalin Cosoi, chief security researcher at Bitdefender, said the lure of free apps blinded some people to the problems they can cause as not all ads are benign.

"The difference between aggressive and benign adverts is that aggressive adware can display more adverts, thus potentially gobbling more from your data plan than a regular app would.

"By jumping in and out of the app, the advert also causes the device to use more resources than an advert-free app normally would.

"They can also modify your browser's homepage without your consent, block websites or redirect the user to web pages displaying apps from the same developer or endorse other types of products, just as PC popup ads used to, years back," he said.

As well as draining battery life and causing the devices to freeze, there are other more dangerous aspects to aggressive adware. Mr Cosoi said that the adware can create "weird" desktop icons trying to trick the user into visiting a particular website.

"While users will be assaulted by weird shortcuts and homepages, there's always the potential risk that those webpages they're directed to could contain actual malware."

It is not as simple to switch these ads off either according to Mr Cosoi just by disabling the internet connection when it is not required.

"While in some cases disabling the Wifi or data will put end to ads, there have been cases in which popups containing commercial content will automatically be displayed regardless of having an internet connection or not," he said.

Richard Clooke, mobile security expert for Symantec's Norton software agreed and said UK users can check if their apps use an aggressive ad networks or have malware at the Appview mobile security website.