OPSWAT doesn't speculate on the surprising variation in the settings applied to different products but the way people acquire software could play a part.

Programs such as McAfee and Norton often come installed on new PCs with trial licenses and it is possible that owners are poorly motivated to upgrade to paid licenses when the trial is over, leaving themselves with under-configured protection.

MSE is a free program users must actively choose to download and adopts optimal settings by default; realtime protection and daily updates happen automatically although scanning must be scheduled.

OPSWAT also found that MSE is the most popular antivirus program in the US with 25.3 percent market share. Globally, it sits in second place on 13.6 percent, behind Avast Free Antivirus on 13.8 percent.

Free antivirus software continues to slowly eat into the share of paid programs, many of which are showing gradual declines in global popularity.