Helping people with computers... one answer at a time.
I agree with you that this is somewhat unsettling. One of the things malware does is corrupt the firewall on your system in order to allow other malware to get on board.
I've decided to dump AVG in favor of Microsoft Security Essentials. Upon installation, I received the following message, "Windows Firewall is still turned off for some unknown error. Try turning it on manually from Windows Security Center." So I went over to the Control Panel and fired up the Windows Firewall. It said that it was already on. Now, I'm not overly concerned because this is my desktop computer sitting behind a NAT router. So if I understand correctly, the Windows Firewall is not really necessary. However, I have some concern that maybe something with the firewall is wrong and not properly functioning even though it says it's on. The initial quick scan of MSE found the Broadcast DSS agent software with one of our old kids' games.
In this excerpt from Answercast #65, I look at a system that is displaying odd behaviors in the Windows firewall.
So I am little concerned myself.
One of the things that malware often does is disable or otherwise corrupt the firewall that might be installed on your system in order to allow other malware to get on board. I'm not saying that that's what has happened in this case, but the fact that you did find some malware on that machine (that apparently AVG did not) leads me to believe that it's at least something to be concerned about.
Technically, you're absolutely right; I would be perfectly comfortable with leaving the Windows firewall off if you're behind a NAT router.
A NAT router prevents basically all unrequested outside contact from the internet. The only way to get a connection to something on the internet is if your machine initiates that contact out. Any contact coming in from the internet that wasn't a part of the conversation your computer initiated can't reach your computer.
That's why a NAT router is such a good firewall.
So with all that as kind of backup, I guess what I would suggest you do is see if you can't run a repair reinstall of Windows. I don't think you included which version of Windows you're running.
I've got a couple of different of articles on that, that you might check out.
In Windows XP, there actually is an explicit "repair" option on the install media.
In Windows 7, you basically perform what's called an "update install" of Windows 7 on top of your existing installation.
Naturally, as you might expect, given that you're going to be doing something fairly major in terms of a repair install; I would suggest that you, of course, backup that machine completely before you start.
I don't think there's really anything horribly concerning here; but I agree
with you that this is somewhat unsettling. I'd probably see if I couldn't get
this issue resolved with a repair reinstall.
Next from Answercast #65 - Why do some smartphone photos come out upside down?
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