This still isn’t a virus
In issue 286 you had a letter from Anne Garvey about MacKeeper. I downloaded LibreOffice onto my new iMac, and MacKeeper somehow managed to download itself with it. Next I time opened Safari, a new search window opened up instead of my homepage, so I referred to your answer. I deleted MacKeeper but couldn’t find the helper folder you mentioned. However, in Safari’s Security preferences I found a plug-in called ‘trovi’ had been added. I blocked the plugin and restarted Safari. It then opened to my homepage, as it should. I have now removed the plugin. Peter Sims MacKeeper is a utility normally classed as a Potentially Unwanted Program (PUP), but for ‘potentially’ you can read ‘definitely’. PUPs are like payday loans: not actually illegal, but the world would be a better place without them. You won’t see the helper folder, unless you’ve run MacKeeper, which isn’t likely since it doesn’t do anything you want.
Trovi Search is another, unrelated PUP that hijacks your homepage. Annoying parasites are sometimes bundled with free software to make money for the developer. More often you’ll get them by accidentally clicking on a fake download button. The button at libreoffice.org is safe, and so is the Mac App Store, but sites offering lots of useful utilities are notorious for this.
Beware of big download buttons on websites, which are often there – alongside genuine buttons – to trick you into installing adware.