has anyone encountered a virus using the name "gukur.sbs"?

That sure looks like an advertisement sent via notification, as was included above. Notification spam.

Here are some directions on removal, for those that like pictures:

Stop unwanted Notifications - Apple Community

In addition to the instructions around checking for and removing unrecognized notifications included in that tip, that tip also describes how to prevent web sites from ever soliciting permission to send notifications and notification spam.

mac-uptodate·com is a valid and registered domain, and is apparently hosted at (behind) Cloudflare.

Go to Safari > Settings > Websites > Notifications, and remove all sites you see there. That will prevent those fake notifications you see in the upper right of your computer.

Also, in my opinion, remove Norton. It is useless and only causes more trouble than it is worth on your computer.

Craig MacKenna wrote:

Mac Jim ID: I think I used the uninstallers. Please tell me how to see whether I got all such demons.

The easiest way to post the free EtreCheck report using the Additional Text option when posting. This will not only show the files in your Launch Folders, but also any Extensions that may be remaining. The report contains no personal information and instructions for downloading and posting the report can be found here:

How to use the Add Text Feature When Post… - Apple Community

P.S. Sorry John Galt, I had not seen you posted the same thing.

Uninstall Norton and all other third party apps that claim to protect. Such apps use system resources while providing no benefit.

See this user tip: Effective defenses against malware and ot… - Apple Community

You can check to see if you've removed all of the supporting files by downloading and running the shareware app Find Any File to search for any files with the application's or the developer's name in the file name.  For the Norton and MacKeeper software you'd do the following search(es): 

1 - Name contains norton

2 - Name contains mackeeper

3 - Name contains macaw

Any files that are found can be dragged from the search results window to the Desktop or Trash bin in the Dock for deletion.

FAF can search areas that Spotlight can't like invisible folders, system folders and packages.  

If you get warnings that the file can't be deleted because it is in use or used by another app boot into Safe Mode according to How to use safe mode on your Mac and delete from there.

Note:  if you have a wireless keyboard with rechargeable batteries connect it with its charging cable before booting into Safe Mode.  This makes it act as a wired keyboard as will assure a successful boot into Safe Mode.

Malwarebytes is the one app that is good to have. It was developed by a long time contributor to these forums and a highly respected member of the computer security community.  The free version is sufficient.

An EtreCheck ought to confirm their eradication by their absence in that report: How to use the Add Text Feature When Posting Large Amounts of Text, i.e. an Etrecheck Report - Apple Community if you would like help confirming.

On top of being a fake message, they're also hoping you don't notice there is no such web site as

mac-uptodate.com

It's macupdate.com

You are all good!

Hopefully you used the uninstaller for Norton and MacKeeper, simply dragging them to the trash will leave behind files that run constantly on your computer in the background. We can help with that as well if that is the case.

A dead giveaway

I've tried twice to go to mac-uptodate.com . Each time, it returns, 404 Not Found.

If it's anywhere, it would be a site that can only be reached with the Tor browser.