Is Macupdate an Apple app or 3rd party

Macupdate occasionally has shown up on my Mac before and usually the only way to delete it has been to shut down my Mac manually. When it reappeared today, even that didn't work.

I also tried searching for all entries or remnants of the name (Macupdate) in system preferences . . . applications . . . monitor activity . . . support . . . java script etc. (and everywhere else I could think of looking), but could find no sign of Macupdate.

The most recent addition I could find anywhere was a string of unrelated letters next to java script dated a week ago.

The only onscreen image right now is the alert from Macupdate.com-apple.menu that a virus was contracted on the last website I visited (highly unlikely because I visit the same site several times a day) . . . and an invitation to remove it immediately by clicking "OK."

I've read mixed reviews of Macupdate dating back several years, so have been reluctant to open it, because I suspect I could be opening a can of worms — but also can't find any instructions for deleting it beyond what I already have tried.

The app also seems to be limited to Safari, because I still am able to access and use FireFox (my backup browser).

Any suggestions where I can find step-by-step directions for deleting Macupdate?

Thanks