The Lookout security team have discovered a new threat they’re naming “NotCompatible” and it’s fairly simple at the moment to keep yourself safe until various systems are updated to protect you. But, like most, this only effects those with unknown sources enabled.
The “application” is usually automatically downloaded because of stock Android browser’s behaviour with files. The file is called “Update.apk” making it seem like a legitimate file, until we get:
Yeah, really a “Security update”. However, most people who are not technical will probably install this if they don’t question why the application needs access to the internet. There’s currently no information as to what this does, but it won’t be anything positive.
However, don’t worry as Lookout (and other security apps) will be preparing updates so you’ll never have to face this issue. Just make sure yet again friends and family (and everyone else you have contact with) with an android device has something to protect them :)
Source with technical information