Scanguard. Friend or foe?
 

It popped up just now while reading some unrelated news. It's claimed to be written by MS 'engineers', but they would say that, wouldn't they?

Now why would anyone want to distribute free software to protect your computer from malware unless their intention was to market your details or monetarise their investment in some other way. No such thing as a free lunch.

When I googled it the other day, the consensus was that it was Malware..

If it popped up uninvited it is, by definition, Malware.

You mean like MSs invitations to upgrade to W10, particularly those that don't take no for an answer.