Security Advisor

Microsoft Security Essentials Fails

When detecting new zero-day threats, the free Microsoft antivirus software was only able to catch 64 percent of attacks.

If unfamiliar with AV-Test, a German security firm that specializes in evaluating endpoint security software, I highly recommend giving the site a bookmark.

AV-Test is the first place to go when evaluating new electronic security safety nets for both your home and enterprise. And it's the first place to go to for information on why Microsoft's Security Essentials, the company's free antivirus program, doesn't hold up well against other free alternatives.

According to the testing firm, Security Essentials was only able to spot 64 percent of zero-day malware attacks during September and October. This is down from the previous testing period in which Microsoft's antivirus was able to spot 69 percent of zero-day threats. Still, this is well below the industry average detection  rate of 89 percent.

As for vulnerabilities that have been out in the open for a few months, Security Essentials did a bit better -- it was able to halt 90 percent of known attacks. Still, this is below the industry-average 97 percent.

In a response to the poor scores, Microsoft sent CNET the following generic statement you would expect: "Microsoft prioritizes protection based on impact and prevalence of malware affecting Microsoft customers from a global perspective. The Microsoft Malware Protection Center actively supports third-party testers to use similar methodology in their test results. We reaffirm that Microsoft is committed to providing a trustworthy computing experience and continues to invest heavily in continuously improving our security and protection technologies."

Based on the recent poor test results, AV-Test has pulled its seal of approval off of Security Essentials. A company can only receive the distinction if it is able to meet 11 of 18 specific criteria, which includes userability, repair effectiveness and detection.

The recent findings were also backed up by NSS Labs' recent findings, which found that Microsoft's free software was only able to block 52.6 percent of exploits the firm threw at it. In comparison, Kaspersky Internet Security 2012, which is not free, was able to block 92.2 percent of threats.

What's your choice for antivirus? Have you found any good, free software out there or is it worth it to spend some money for a more thorough product? Let me know at

About the Author

Chris Paoli is the site producer for and

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Reader Comments:

Thu, Dec 13, 2012 Dan Iowa

What's missing from the antivirus testing mentioned above is a measurement on stability. AV needs to work well as a background process. The reason MSE does so well is not because some testing firm found it detected this vulnerability that something else did not detect. The reason is because it is far more stable than most other anti-virus systems out there. Not surprisingly, if your testing doesn't involve actually having to support production services, things like Avast and Symantec can score well. However, in the real world, it has to run for weeks at a time without crashing your systems, and that is where MSE seems to shine over many of the other options.

Thu, Dec 13, 2012 Marc

It is not important if we "like" MSE! It's important if MSE does its job! You do not have to "like" your AV software. You should trust it.

Wed, Dec 12, 2012 Jim

I have no problem with MSE. It's fast, well-integrated, and have yet to have a virus problem.

Sat, Dec 8, 2012 Bryan Waltham, MA

MS Security Essentials was the first FREE malware/av software from MS and worked great and didn't bring your system to a crawl like Norton or (shudder) McAfee. It was also the first to baked into the OS to look for machine level root kits which none of the other products were capable of at the time. With the release of Windows Security Essentials 2 I can't imagine using anything but that.

Thu, Dec 6, 2012 Roger Hampton United States

How do I remove Microsoft Security Essentials? I am unable to install McAfee Total Protection while it is in my computer? I need to uninstall this program/. Roger Hampton (503) 293-5655

Thu, Dec 6, 2012 Allan US

Rocker makes a good point however we can only assume that the test run previously were done in the same manner as the one in this report. It also appears that multiple vendors/testers recorded similar results repeatedly. I am a user of Security Essentials and likely will ride out the storm. I like it, it is not as bulky as some of the others, it integrates with the OS better than others and it is free. I'm sure with news like this MS will look into it considering they are touting it for mobile devices etc.

Thu, Dec 6, 2012 DC Ireland

Where does this leave Windows Intune Endpoint protection.

Thu, Dec 6, 2012 Craig

Like the other comments, I have used and recommended Security Essentials and it has worked quite well. I also have layers of security but I will have to take another look at this report.

Wed, Dec 5, 2012 Ethan Seminoff United States

I've recommended this software in the past as it used to get good reviews. I use it at home without any issues at all. However I do consider myself to be a little more educated security wise than the average Joe (as are most IT people) so it may just be I haven't stumbled on anything malicious in a while. I find it interesting that in the AV-Test results that Avast is at the top of the free protection list...they used to be total crap. In any case I will think twice before recommending this software to others since there are better options out there again.

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