When Microsoft killed off OneCare, it promised a kind of replacement--a small, free anti-malware utility. The company has made good on that promise with the release of Microsoft Security Essentials 1.0. You can download it now at www.microsoft.com/Security_essentials/. I evaluated the product and determined that its protection is good, but not great. Security experts Andreas Marx of AV-Test.org put the product through his own testing and drew similar conclusions.
Security Essentials successfully detected all of AV-Test's current wildlist samples, nearly 4,000 of them. In a test using over 500,000 samples of viruses, worms, Trojans, and other high-risk malware, the product detected 98.44 percent. It wasn't quite as effective in a separate test using about 14,000 adware and spyware samples, but it still detected 90.95 percent of them.
Marx observes (and I concur) that Security Essentials doesn't include any behavior-based detection technology. He excuses Microsoft on the basis that in general such dynamic detection features are found only in full security suites. Here I have to disagree. Many standalone products such as Webroot AntiVirus with AntiSpyware and Spyware Doctor with AntiVirus include dynamic detection features in their arsenal of protection.
In AV-Test's analysis, Security Essentials successfully removed the active components of all detected malware but left behind significant amounts of non-executable malware traces. That's a better result than I measured - I found that Security Essentials left behind executable files for many of the samples. It also successfully removed all of their active rootkit samples but left several of mine running even after alleged cleanup.
So should you rely on Microsoft Security Essentials for free protection? I'd say no, unless you strongly value the Microsoft name. My own testing suggests that you'll do better with one of the other free anti-malware solutions such as AVG Anti-Virus Free or avast! antivirus Home Edition.
