Microsoft has revealed that 1 out of every 14 downloaded programs is later confirmed as malware. The data comes from the software giant's SmartScreen Filter team.
SmartScreen Filter was originally introduced in Internet Explorer 7 by extending the browser's phishing filter to include protection from socially engineered malware. Every website and download is checked against a local list of popular legitimate websites. If the site is not listed, the entire address is sent to Microsoft for further checks, but if it has been labeled as an impostor or harmful, IE7 will show a screen prompting that the site is reported harmful and shouldn't be visited. From there, you can visit your homepage, visit the previous site, or continue to the unsafe page.
In IE8, if you attempt to download a file from a location reported harmful then the download is cancelled. In IE9, the protection against malware downloads is extended with SmartScreen Application Reputation, which warns you if you are downloading an application without a safe reputation from a site that does not have a safe reputation.
Microsoft also announced that the feature now blocks between 2 million and 5 million attacks a day for IE8 and IE9 users. Since the release of IE8, SmartScreen has blocked more than 1.5 billion attempted malware attacks.
The company says that IE9 users are choosing to delete or not run malware 95 percent of the time from the new Application Reputation warnings. That leaves 5 percent that are still being clicked-through, despite being told the downloaded programs could be infected.
Internet Explorer 9 was released on March 15, 2011. Even if you barely use IE, you should still upgrade, if only for the improved security features.