I have not encountered the image you have displayed - however it appears it is asking you to install and set-up Norton Mobile ecurity - whihc comes a spart of your free Comcast Norton Security Online. Hopefully the following link will assist you in getting this corrected:
Please let us know if this helps.
Anyone else dealing
With this? It’s taken over my entire house.
The KRACK vulnerablity has been known for some time now, and has been extensively discussed in this thread.
Pretty much every hardware manufacturer has issued patches to fix this. If you haven't downloaded the latest firmware for your devices yet, now would be a good time to do so.