I think this was installed by a fake Adobe FLASH installer. I removed most of it myself, but I could not get rid of this problem with Chrome: If I started Chrome and then killed all the open tabs, what was left was a chrome widow that had a search box in the middle of the Chrome window. Above the search box it said SEARCH in google colors, below the search box was a button that said SMART SEARCH. If you clicked on the button, it brought you to a weKnow.ac website. which looked like this picture: https://www.pcrisk.com/images/stories/screenshots201802/chumsearch-com-hijacker-main2.jpg (or see attached pic ) Also on that SEARCH page it kept showing ads for things like MacKeep, etc I tried many procedures from many different websites to no avail. I tried resetting Chrome, re-installing Chrome, set Chrome's home page and search providers, remove files from various locations, etc, etc. Many websites recommended to use COMBO CLEANER for MAC or FRESHMAC remover tools but I was not able to find trust worthy reviews on those pay-for-removal tools. I did install and run Malwarebytes for MAC, it did find and remove some things, but it did not fix this issue. The only way I was able to un-install or remove the remove SMART SEARCH and weKnow.ac malware virus from Chrome on Macbook Mac iOS was to do this from: https://discussions.apple.com/thread/8534513 "weknow.ac" changes a group of Chrome policies so as to set a new default homepage, new tab behavior, etc. You can see your current Chrome policies by typing chrome://policy/ into your URL bar. If you're infected, it should be very obvious as the half-dozen or so policies changed by weknow will be displayed. Use the command line to delete / modify the affected policies. You do this by opening up "Terminal" and copy and paste each of the following entries below. I did each one at a time. I copy and pasted the first line and then hit enter and then went to the next until I had finished all 6 below: defaults write com.google.Chrome HomepageIsNewTabPage -bool false defaults write com.google.Chrome NewTabPageLocation -string "https://www.google.com/" defaults write com.google.Chrome HomepageLocation -string "https://www.google.com/" defaults delete com.google.Chrome DefaultSearchProviderSearchURL defaults delete com.google.Chrome DefaultSearchProviderNewTabURL defaults delete com.google.Chrome DefaultSearchProviderName Quit Chrome and restart it and voila the virus will be gone. I tried everything and 3 phone calls with Apple and this was the only thing that worked.