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What to do after running MalwareBytes on your Mac

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If you’ve ever seen your search engine in Chrome, Safari or Firefox mysteriously redirected to a strange, non-Google search engine, or seen pop-up ads warning that your Mac may be infected, or that advertise dubious services, you’re probably a victim of adware or malware on your Mac.

The most common way of getting this junk are fake notices saying your Flash player is out of date — if you see one, please disregard it. If you really need Flash, use Chrome, which has it built in.

MalwareBytes has for years (dating from its origins as AdwareMedic) been the most effective tool for getting rid of the most common kind of Mac adware and malware. It’s free to perform manual scans for malicious software; you can subscribe for automatic protection.

However, like all malware protection software, it’s not perfect. It doesn’t always find absolutely everything, and even when it does remove garbage software from your computer, it sometimes doesn’t perform final steps required tor return things to fully normal, and prevent you from potentially being reinfected.

So, once you’ve performed a scan with MalwareBytes, and it removes whatever it finds (or gives you a clean bill of health, rightly or wrongly), you need to take a few more steps.

  1. If MalwareBytes finds anything, restart your Mac, whether or not you are instructed to. After restart, reopen MalwareBytes (if necessary), and Clear the Quarantine.
  2. Go to the Apple Menu, and choose System Preferences. See if there is an item called Profiles — if it’s there at all, usually it is in the fourth row. If it’s not there, great. If it is there, go into it, and remove any profiles that you can’t account for or, are unsure of the purpose for. Normally, you would not have any profiles unless your computer was set up by a corporate IT department, or have installed personal VPN software. Close System Preferences.
  3. Go to the Apple Menu, and choose System Preferences (again). Go to General (top left). Make sure that default web browser is set to whatever you prefer.
  4. In each browser (Safari, plus Chrome and/or Firefox if you have them installed), go to Extensions. In Safari, this is under Safari->Preferences->Extensions. In Chrome, it is under Window -> Extensions. In Firefox, it is under Tools->Add-Ons->Extensions. Remove any extensions you can’t account for or are unsure of the purpose of.
  5. In each browser, check that the default search engine is Google (or DuckDuckGo, if you are concerned about privacy and can live with inferior web searches). In Safari, this is under Safari->Preferences->Search. In Chrome, go to Chrome->Preferences->Search Engine — but if it won’t let you change it, read our next post for what to do. In Firefox, go to Firefox->Preferences->Search. Sometimes, the search engine says to something innocuous like “Default” or “Default Browser” or “Search” — these are rogue, and you should change them. It should always be Google (or DuckDuckGo).
  6. In each browser, open a new window. Check that the home page is what you want it to be. If you don’t recognize whatever is there, change it to a site you prefer, or to google.com if you can’t think of anything. In Safari, you can set it under Safari->Preferences->General (default is https://www.apple.com/startpage/). In Chrome, go to Chrome->Preferences->On Startup (default is “Open the New Tab Page”). On Firefox, go to Firefox->Preferences->General (default is “Mozilla Firefox Start Page”, which you can get by clicking “Restore to Default”).

At this point, your Mac should be fully back in action, and all of your browsers should behave normally.

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