Windows Defence Master is a fake antivirus programs that attacks your computer and gets installed in your computer without your permission. It belongs to fake Windows rogue and it has many other siblings, like Windows Defence Unit or Windows Security Master. Acting like other fake antivirus programs, Windows Defence Master first scans your computer and then it pops up fake alert telling you that there are many threats in your computer and you need to handle it immediatele. If you follow its advice, Windows Defence Master may ask you to purchase a full version of it. You have option to ignore it but sooner, that message will pop up annoying you.