How to remove viruses or malware not found by Norton or other antivirus programs?

First, you should remove any anti-virus apps, as well as anything that claims to "clean", "speed up", "refresh", etc. your Mac (such as CleanMyMac, CCleaner, and many others). These apps are useless at best, and downright malicious at worst, often removing important system files to free up space that doesn't become evident until much later. Apple's built in security is all that is required.

You can read more about anti-virus softwares here and Mac's already sufficient built in security here. The only exception to this is Malwarebytes, which you can read about below. The important thing to remember is that YOU are the best defense against malware. Use your common sense when downloading anything from the Internet (especially if Mac advises against it). Apple's advice regarding malware can be found here. There are no native viruses that can harm Macs in the wild.

Your Chrome issue sounds related to an accidentally downloaded piece of adware. Besides this, Chrome is a known memory hog that won't run too well on High Sierra anyway. Other good options include the built-in Safari, Firefox, or Brave.

If you want to scan your Mac for malware, Malwarebytes is a generally trusted choice, as it was developed a while ago by a trusted member of this community. You can download it for free here. Any other anti-virus softwares should be skipped, no matter how tempting they sound. Use this before proceeding with the use of Migration Assistant below.

For your Time Machine backup restoration, follow the instructions here to start. See the image below, and only transfer what you need to. If you can get your downloaded Applications again without too much trouble, don't import them with Migration Assistant. Your User Profile contains everything in your Finder's Home folder. If your Malwarebytes scan identifies issues in certain areas of your computer, don't import the sections if you want to be absolutely sure no malware comes through. It's often difficult to remove it yourself (and developer instructions are usually less than helpful).

I hope this helps!

Norwegian_Macfan68 wrote:

Highly appreciated! So you recommend installing the High Sierra OS X from fresh before doing the Restore?

Exactly. You'll need to reinstall OS X High Sierra, then use Migration Assistant to transfer the files.

To get High Sierra, first try booting into Recovery with Shift-Option-Command-R during startup to be offered the macOS that came with your Mac, or the closest version still available. If that's not High Sierra, you'll need to install it from the App Store's old installers. You can find High Sierra here - macOS High Sierra - App Store

If you can't install it with the installer (especially if you erase your disk), you'll need to make a bootable installer. Instructions can be found here.

Post back with any problems you have!

To perform this action will require booting from a Bootable Installer. 

The Bootable Installer can Only be performed on an Apple Computer 

This will have to be performed from a Qualifying Computer to run the version of macOS to be made on the Bootable Installer. Example : Bootable Installer of High Sierra would have to be done on a computer that Qualifies to run High Sierra.

Notation: If the computer being used to perform this action is Too New or Too Old to qualify to run the version of macOS - this computer can not be used.

Alternative is, to gain access to a Qualifying Apple Computer from a family member, friend or associate.

Once that is done read on for preparing the Destination computer  >> Only works on Intel Based Apple Computers.

1 - Shutdown computer and disconnect all external drive Except the newly created Bootable Installer.

2- Restart and immediately hold the OPTION key until the Startup Manager appears and choose the USB Drive. 

3 - It will present options >> Disk Utilities >> View >> View ALL attached Drives. 

4 - Choose the Upper Most Drive ( not the volumes indented and list below ).

5 - Formatting for macOS 10.13 High Sierra and below requires HFS Journaled with the GUID Partition Map

6 - Once that is done >> backup out of Disk Utilities and choose install macOS. 

7 - Follow the prompts and it may automatically reboot several time. 

8 - Upon a final reboot - Setup Assist will present with the newer version of macOS.

first off, there are no viruses that affect the Mac. you should uninstall Norton and / or any other antivirus apps that you have installed. those types of apps are well known to negatively affect macOS while providing zero benefits due to the sealed system that only apple can make changes to.

that said, from your description it does sound like you have managed to install some malware / adware. I will recommend downloading and running the free version of Malwarebytes for Mac. it will remove most malware from your Mac. and once you're done with it, you can use these instructions to remove it. uninstall Malwarebytes for Mac,

and finally, you should read this informative user tip to help you stay safe in the future. Effective defenses against malware and other threats - Apple Community. it's a long article, but it's worth your time to read every word.

Don't worry- app preferences aren't stored in macOS. Time Machine takes care of that (it basically clones your system). It does not backup macOS, as that would be redundant and a waste of space (macOS X High Sierra is the same everywhere). After you reinstall macOS on your new disk, simply use the aforementioned Migration Assistant to move your data (including app preferences and settings).

Bottom line- your Keyboard Maestro settings are safe ;)

you're welcome. :)