My question concerns the defaults as established by software programs,
especially security programs. I have an anti-virus firewall and anti-spyware
program that comes with it. When I click to do a scan, there comes up a menu of
Quick Scan or Complete Scan. The Quick Scan is always marked as the default
operation. How do you feel about that? On occasion, I do a complete scan, but it
doesn’t seem to catch anymore than if I use a Quick Scan. The program is very
well known and is usually in the top 10 of security programs. I don’t want to
give out the name for the program, so as not to influence any of your readers if
this question is posed.
In this excerpt from
Answercast #22, I look at the way anti-malware programs look for viruses and
spyware and how that fits into a quick scan.
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Is a Quick Scan okay?
So, no, it’s not an issue. It’s very common.
What we need to understand is the difference between a Quick Scan and a
Complete Scan or a Full Scan.
Malware in general, depending on the kind of malware, whether you’re talking
spyware or viruses and so forth, tends to infect certain types of files in
For example, they infect files that are installed as part of Windows. Or
they infect files that are installed or referenced by the registry or only .exe
files, that kind of thing.
What that means is that the anti-virus softwares, the anti-malware tools,
can all make a couple of assumptions that allow you to cover 99% of all known
malware by only scanning the areas where those malware typically infect.
Quick scan has a lot of benefit
So what you’re really getting is a lot of benefit by doing a Quick Scan that
only scans those areas; without having to spend all of this time scanning
absolutely everything on your computer for very little additional benefit.
As you’ve seen, typically, a complete scan won’t find anything more than a
Quick Scan… only because the Quick Scan has already scanned all of the areas
that typically have malware.
Complete malware scan
A complete scan, or a full scan, (as you might expect) scans absolutely
every file on the hard disk that you’re looking at. So it would scan your .doc
files, your .mp3s, your .jpegs, your pictures, your music. The chances of there
actually being malware in those files is so small that it makes a lot of sense
to not bother scanning them. That’s what a Quick Scan is all about.
Typically, my recommendation is to be relatively secure and not make those
kind of assumptions. Go ahead and run a Quick Scan when you’re running a scan
manually. But when a scan is run automatically, consider letting that be a full
scan. It will take longer but it will happen in the background.
In my case, for example, I let it happen overnight. That way, you know that
even that little tiny percentage of possibilities is not going to happen
because you have scanned everything.
If you’re scanning manually, you’re probably interested in getting a fairly
quick answer about whether or not your machine is infected. A Quick Scan is
going to give you an answer with 99% accuracy within the scope of that
particular anti-malware program.
So, it doesn’t concern me at all. It’s pretty much what I expect from
almost every anti-malware tool regardless of which one you happen to be
End of Answercast #22 Back to –