I occasionally use the Scan function, but it never finds anything. Now I’m starting to wonder if it’s even necessary. Since Avast actively monitors for viruses while I’m online, then it would catch any viruses that try entering my computer, right? If a virus had to be found by doing a scan, it would mean that a virus had already been on my computer in the first place, perhaps before I installed Avast. But once Avast is installed an active, anything that would make its way onto my computer and be found with a scan would have been caught by Avast before it ever got onto my computer in the first place. Am I correct about this, or does the scan function have a purpose I’m not understanding?
you may get a infection before avast have signature for it, but as soon as avast get signature it should be detected by avast realtime protection.
Also a scan is usefull in a cleanup to make sure evrything is detected/removed
A friend may arrive with a removable drive full of music/movies, it may be smart to scan it before any file is run
A friend may arrive with a removable drive full of music/movies, it may be smart to scan it before any file is run
Ah yes! This is one thing I forgot about. Not everything comes via the internet.
For usb drives/sticks I suggest to install McShield next to avast if you don’t have/use it already.
Yepp, MCShield is highly recomended
It did some work here today > https://forum.avast.com/index.php?topic=190985.0
From what I’ve been able to find out about it, it sounds like something that is included with McAffee, which I don’t have. Also said to be very CPU-hungry. Does it have a purpose beyond what Avast, Malwarebytes, and ADWCleaner do? I already have those programs.
Not part of McAffee.
You’ll find it here: http://www.mcshield.net/
As said it has nothing to do with McAfee.
MCShield is a special tool that ONLY target those type of malware that use removable drives to spread, and it is able to do it without signatures. It use no system resource as it is dormant until a USB device is plugged in, then it wake up scan and clean if anything is found and goes to sleep again
This forums malware removal experts use it for cleaning USB devices
Yep 
Most of us are using / recommending MCShield.
Greetz, Red.
MCshield sounds good, but I have a question.
BY what mechanism does malware on a USB Flash drive get executed when it is inserted?
I thought Windows Autorun , from Windows Vista and newer, was by default disabled
with the result that any autorun.inf file would be unable to execute any target.
Is there some other way something could run ?
Autorun is just one vector used.
Her is a 16 page topic where i guess evry question there is to ask about MCShield is asked
especially see reply from argus / magna86 and dr_bora who made the program
See here > https://forum.avast.com/index.php?topic=104046.0
Topic is from 2012 and as you see many were sceptical then and are today using the program
Thanks Pondus,
I will review your link.
A partial list of anti-malware programs would start with McShield. It would also include Unchecky, Malwarebytes Anti-Exploit Free and so on.
Point is layered protection.