Hey everyone,
My posting restriction has been lifted, so now I'm able to share an update on this issue.
19 hours ago, hazelnut said:
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Interesting read that involves the role WMI plays.
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<a href="https://stackoverflow.com/questions/13615203/check-for-third-party-firewalls-on-a-machine" rel="external nofollow">https://stackoverflow.com/questions/13615203/check-for-third-party-firewalls-on-a-machine</a>
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I converted the C# script that had been posted there to an .exe File through PowerShell using the following command:
C:\Windows\Microsoft.NET\Framework\v4.0.30319\csc.exe /t:exe /out:MyApplication.exe MyApplication.cs
Make sure to create a .cs file (using Editor) containing the C# script beforehand. Once I converted it to an .exe file, I was able to run it and it then gave me this result:

This means that Kaspersky Internet Security is still registered as a third-party firewall in Windows, even though it had been uninstalled a few months ago (incl. all registry entries and leftover files).
17 hours ago, hazelnut said:
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Have you ever used Windows Repair by Tweaking.com?
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I was just wondering if it would reset the WMI
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I've also tried performing the WMI Repair through the Windows Repair by Tweaking.com application. Unfortunately, it did not change anything and Speccy still mentioned Kaspersky Internet Security in the firewall section.
16 hours ago, johnccleaner said:
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Similar to what Hazel had you run for finding the AV in WMI, this command:
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wmic /Node:localhost /Namespace:\\root\SecurityCenter2 Path FirewallProduct get * /value
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should show the Kaspersky firewall.
From there, the instructions in: <a href="https://support.cloudradial.com/hc/en-us/articles/360049084271-Removing-Old-Antivirus-Listings-from-Security-Center" rel="external nofollow">https://support.cloudradial.com/hc/en-us/articles/360049084271-Removing-Old-Antivirus-Listings-from-Security-Center</a> altered to FirewallProduct instead of AntiVirusProduct may allow you to finally exorcise it. (It goes without saying to be very, very careful, of course.)
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This actually resolved this issue and Speccy now no longer mentions Kaspersky Internet Security at all. ?

I'm glad I was able to get rid of it and thanks again to every person who has participated in this thread ?