Microsoft Security Essentials, the most popular Internet security software that is installed on most Windows PCs,  has failed the independent testing by AV-Test, missing out on the testing company’s coveted certification.

AV-Test, a well-known independent testing lab in Germany, conducts a new round of “real-world” testing on various security software suites every two months. In the two most recent tests, which span from September to December 2012, Microsoft scored too low to be certified by AV-Test. To put it in perspective, 22 other anti-virus suites were certified in this round of testing, and only three failed.

So how bad was the score?

1) Microsoft had the lowest score for protection out of all the security suites tested, scoring only 1.5 out of 6.

2) They scored only 71% on protection against zero day malware threats, which includes malicious software that has yet to be analyzed and rolled into an antivirus program’s definition files.

3) They also scored only 92% in detection of malware that had been discovered in the past 2-3 months.

To put it in perspective, the top-rated security suite, Bitdefender, scored a perfect 100% for each of these categories.

Microsoft did have one of the highest scores for usability, according to AV-Test. They scored a 5.5 out of 6 in independent testing, with high marks for both performance (not slowing down your computer) and avoidance of false detections.

Granted, independent testing is not the end-all, be-all of how security software suites are rated, but they do give a pretty good picture of how each suite handles a sampling of dangerous malware. If you currently use Microsoft Security Essentials to protect your computer, it might be a good idea to check out some of the other 22 security software suites that did score certification from AV-Test. We review a good number of them here.