Thousands of Android apps were found out in a recent study to have been used by a malware to view ads and watch videos without the user knowing it. According to the researcher, fake ad traffic could cause advertisers as much as US$10m daily.

Digital marketing firm eZanga has revealed in a study that more than 1,300 Android apps have been the hotbed of one malware that makes people's smartphones view ads and videos unbeknownst to them. After the study, it has confirmed that the number of impacted Android apps increased to more than 6,000 apps.

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Using its Anura ad protection software, eZanga was able to identify one module from a software development kit that lurks inconspicuously in apps and run ads and play videos while the user is away. The phone might be sleeping while the activity transpires but it consumes bandwidth and battery life.

One app with hiding SDK module has been downloaded from the Google Play Store for over 1 million times. The company estimated advertisers' loss, in this case, may range between US$2m to US$10m daily.

Most of the apps affected are live wallpapers or free backgrounds featuring nature scenes, adorable animals and other stunning effects, as well as the File Explorer app and lots of photo-editing software.

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According to eZanga chief executive Rich Kahn, Google has already removed all the apps it named in the study after a few weeks. Google tells CNBC in a statement that Google Play automatically scans uploaded apps for potentially malicious code and spammy developer accounts before they are made available on the app store.

Khan notes that it is important to update the phone regularly to avoid malicious SDK modules from residing in apps for too long.