Microsoft’s Security Essentials (MSE) remains a hugely popular consumer antivirus product but new figures suggest that its Windows 8 successor, Defender, is losing out to third-party alternatives.

Security tools firm OPSWAT has carried out market share analysis of antivirus clients using numbers from its AppRemover tool in the past, but the latest stats are derived from its new security assessment application, Security Score, released in June.

This time the firm divided its results into three categories; the most popular vendors overall, the most encountered individual products and the most encountered individual products that had real-time protection enabled (or not), coming up with some interesting numbers.

Not surprisingly, the frequency of Microsoft’s Security Essentials (the standard Windows antivirus client) and Windows Defender (which was upgraded to succeed it on Windows 8) topped the list at a combined 25.8 percent, just ahead of Avast Software’s 23.6 percent. A clutch of other familair vendors scored under 10 percent, including AVG, Symantec, Eset, Avira and Kaspersky.

The top individual product was in fact Avast’s Free Antivirus with 19.5 percent, followed by MSE on 18.3 percent, with the Windows 8-only Windows Defender on 7.7 percent.

There were some limitations to this element of the study, starting with the small US-biased installed base of Security Score due its recent release. However, the numbers it generated chime with past OPSWAT products share results that used larger data sets.

More interestingly, when the company logged the number of occurrences of each vendor where realtime protection was not enabled (i.e. where the software was present but inactive or disabled), they found that two thirds of Windows 8 users were using a second program for realtime protection.

Windows Defender comes enabled on every install so users who choose to supplement it are making a positive choice to do so. By contrast, MSE on Windows 7, Vista and XP was far more likely to be enabled, 98 percent of the time to be precise.

“RTP status can be seen as a metric for product usability and/or effectiveness; if a user views an antivirus product as effective and easy to operate, the user is more likely to have that product actively running on his or her machine,” concludes OPSWAT’s researchers.

It could also be the case that Windows 8 users are confused about the level of protection offered by Defender or even whether, given its self-effacing design, it is present at all. A study by OPSWAT from 2012 found that antivirus programs were often poorly configured.

On cloud backup use, OPSWAT found Google’s Drive on 22.5 of systems, Dropbox on 19.5 percent, and Microsoft’s SkyDrive (soon to have its name changed) on 15.4 percent. The top 10 vendors accounted for more than 83 percent of the market, which suggests that this particular market is now too mature for outsiders to make headway.