You are aware that there are scripts running next to any giving website that can be made to look like they originate from the website you are currently watching. Can be something you picked up from another website.
Ads without exit button? That is fishy, whichever way you look at it.
Anyway, best to scrub your system with anti-malware tools such as: Junkware Removal Tool (jrt for short), rkill, ADW cleaner, UnHackMe. In your case ADW cleaner should not be necessary, because you are already running MalwareBytes. The others are an addition and only do their work when you activate them, so no real-time protection. Both look spartan and will terminate all other running processes, so make sure you save whatever you are doing first before running jrt or rkill. Often jrt and rkill find what MalwarBytes misses and vice versa.
You can also use the Glasswire Monitor software for free (this limits the functionality) for personal use. That is a pretty nice looking tool to see if your computer is putting out traffic that is not legit. It does this in a very graphic way, that makes it quite clear what is going on your computer that is network related, even for the lay person.
Then there is UnhackMe. I got it some 6 months ago as a giveaway for free and it is very thorough, but the buttons look weird and the standard GUI layout rules are not followed at all. And there is also the badly translated English. But if you can put yourself over that, it does work. Even though it takes it sweet time to do so. it also requires user interaction during the scan and removal process.
But after you run these tools (and a reboot), you can be pretty sure your system is clean enough to surf again (but with a bit more caution hopefully). I'm not familiar with the Norton AV software, haven't touched that software with a ten foot pole for many, many years now. I like the unobtrusiveness of free BitDefender AV software, but with common sense, Windows Firewall and Windows Defender you can be just as safe, except you don't lose a lot of your computers resources in the process. The free versions from Avast and Avira have become real hogs and are spewing almost continuously adverts in your screen to buy their full fledged products and subscriptions and services and the kitchen sink. Practically as irritating as having a virus on your system.
-Shades
JRT ---> ADW Cleaner found five and removed five:
# -------------------------------
# Malwarebytes AdwCleaner 7.3.0.0
# -------------------------------
# Build: 04-04-2019
# Database: 2019-04-05.4 (Cloud)
# Support:
https://www.malwarebytes.com/support#
# -------------------------------
# Mode: Clean
# -------------------------------
# Start: 04-05-2019
# Duration: 00:00:01
# OS: Windows 10 Pro
# Cleaned: 5
# Failed: 0
***** [ Services ] *****
No malicious services cleaned.
***** [ Folders ] *****
No malicious folders cleaned.
***** [ Files ] *****
Deleted C:\Windows\System32\a.bat
***** [ DLL ] *****
No malicious DLLs cleaned.
***** [ WMI ] *****
No malicious WMI cleaned.
***** [ Shortcuts ] *****
No malicious shortcuts cleaned.
***** [ Tasks ] *****
Deleted C:\Windows\System32\Tasks\FreeDownloadManagerNetworkMonitor
***** [ Registry ] *****
Deleted HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Schedule\TaskCache\Boot\{BDAA38DF-FF54-4CAA-A2A1-4B5462A0FDD8}
Deleted HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Schedule\TaskCache\Tasks\{BDAA38DF-FF54-4CAA-A2A1-4B5462A0FDD8}
Deleted HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Schedule\TaskCache\Tree\FreeDownloadManagerNetworkMonitor
***** [ Chromium (and derivatives) ] *****
No malicious Chromium entries cleaned.
***** [ Chromium URLs ] *****
No malicious Chromium URLs cleaned.
***** [ Firefox (and derivatives) ] *****
No malicious Firefox entries cleaned.
***** [ Firefox URLs ] *****
No malicious Firefox URLs cleaned.
*************************
- Delete Tracing Keys
- Reset Winsock
*************************
AdwCleaner[S00].txt - [1745 octets] - [05/04/2019 13:33:08]
########## EOF - C:\AdwCleaner\Logs\AdwCleaner[C00].txt ##########
