In the current comparison tests run by AV-Test, the free Microsoft Security Essentials (MSE) suite was the only anti-virus product that didn't meet the institute's certification criteria. The laboratory publishes its results every other month. In the previous test, Microsoft's scanner performed well enough to be certified; MSE last failed the test two years ago.

AV-Test examines security programs' performance in terms of protection and repair as well as their usability, and candidates can achieve a maximum of 18 points in total. At least 11 points are required for certification; MSE narrowly missed this mark, scoring 10.5 points. Two months ago, Microsoft's anti-virus program was still achieving 12.5 points.

Points were lost in all areas: the program lost half a point in terms of protection and usability, and a whole point in the repair category. The protection result was mainly caused by MSE blocking fewer current threats: of the newly arrived malware samples, MSE only detected about 64% in October, while the average detection rate was 89%. Of the malware samples that were two to three months old, MSE detected 90%; the average detection rate was 97%.

"We can no longer recommend MSE in its current condition", the CEO of AV-Test, Andreas Marx, told The H's associates at heise Security. "Other free programs such as Avast, AVG, Avira or Check Point (ZoneAlarm), perform significantly better in this test area [editor's note: protection]. Their repair performance tends to be better as well", he added.