Windows 8 will include an improved version of the Windows Defender anti-malware software http://blogs.msdn.com/b/b8/archive/2011/09/15/protecting-you-from-malware.aspx
This means that all computers running Windows 8 will, at least when they are first powered on and connect to the Internet, have up-to-date anti-malware protection.
Microsoft has also indicated that if a third party anti-malware application is installed on a computer running Windows 8, Defender will essentially deprecate itself in favor of the alternative.
As you can probably guess, When Windows 8 releases, OEMs will continue to provide trial subscriptions from anti-malware vendors with the machines that they ship. This happens because anti-malware vendors provide OEMs with compensation for including trial versions of their software with new machines.
The study cited above found 12 months after Windows 7 was released, roughly 25% of computers running Windows 7 didn’t have up-to-date anti-malware software. This was down from almost 100% of computers having anti-malware software at RTM. The proposed hypothesis was that a year down the track, 25% of people had let their initial trial subscription expire and hadn’t got around to, didn’t realize that they needed to, or flat out didn’t intend to renew their subscription.
The problem is that anti-malware software that doesn’t have up-to-date subscriptions is about as effective at protecting you from new strains of malware as gumboots are for protecting you from crocodiles.
There is no real reason to believe that people running Windows 8 will be any more diligent about keeping their anti-malware subscription current than people running Windows 7. Which suggests that 12 months down the track, sometime in mid 2013, approximately 25% of computers running Windows 8 won’t have up-to-date anti-malware definitions.
While Windows 8 will be able to detect when someone hasn’t updated their definitions for some time I suspect it’s unlikely that the operating system will prompt the user with something along the lines of “hey, you’ve let VirusAnnihilator expire, do you want to renew your subscription or do you want Windows Defender to take over from here?” It would be cool if it did, but I suspect that such useful behavior would cause current anti-malware vendors to lose their biscuits.
Now that Windows 8 ships with an anti-malware solution, it is possible, that by including trial software on computers running Windows 8 (and hence deprecating Windows Defender which, if left alone in the first place, would likely keep itself up to date), that anti-malware vendors might be making some people’s computers less secure in the long term.
Of course we won’t know the score until Windows 8 releases and perhaps Microsoft has some sort of cunning plan to deal with the problem of people letting their third-party anti-malware subscriptions expires.
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