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How often do I need to run complete anti-malware scans?


I live in an adult community with 200 homes with computers. I’ve installed
free protection software on many of their computers that have XP, Vista, and
Windows 7. The most commonly asked question is: How often do I run complete
scans with AVG, Spybot, Malwarebytes, Superantispyware, CCleaner? Can you
recommend a schedule? Daily, weekly, monthly, when?

In this excerpt from
Answercast #77
, I look at the types of virus and spyware protection software
that needs to be running automatically on the typical computer.


How often to run scans?

Well, unfortunately, there really isn’t a blanket answer to that. It really depends more then anything else on exactly how the computer is used – and the savviness of the person using it.

If I had to pull a number out, I would say weekly with daily partial scans.

In other words, the way I have my software configured on all of my machines is that the Microsoft Security Essentials performs what they call a “quick scan” every night. That does a good job of ferreting out anything that may have happened during the day and, in a way, localizing the damage.

Scanning schedules

If I were concerned about more extensive malware of some sort, then yeah, I might run a full scan weekly.

In fact, I don’t run a full scan at all. I only run them as needed: if I’m actually tracking down a problem. So the short answer is that:

  • The automated stuff, that happens automatically by these tools – typically daily is fantastic.

  • It’s not something you ever have to think about – it’s just something that happens.

Manual scans or more complete scans on top of that are something that you need to judge based on: how the machine is being used, whether or not the person using it has a good sense for what kind of trouble they might be getting themselves into, and then knowing how to steer clear of it.

What tools do you need?

The other comment I want to make here is that you’ve got a lot of stuff on your list: AVG, Spybot, Malwarebytes, Super Anti-Spyware, CCleaner. That’s a combination of tools that I’m hoping you’re not trying to run on each machine.

  • AVG is anti-virus and I think they have an anti-spyware component.

  • Spybot is, of course, anti-spyware.

  • Super Anti-Spyware is anti-spyware.

Between those three, you may have three anti-spyware tools. You don’t need to run all three at the same time. You need to pick one and have it running continuously. I would then perhaps pull out another one as a tool to use in case of problems.

Malwarebytes is in that same category. I actually recommend that people have it – but they don’t really need to run it unless they’re tracking down a problem. It certainly gives you an added layer of security if you do enable its automated tool.

I’d pick that one, I guess, at weekly. Once again, I don’t run it all unless I’m running into a problem or trying to diagnose something.

CCleaner doesn’t actually fall into those categories at all. CCleaner is a clean-up utility – not really an anti-malware kind of a tool. Once again that boils down to how does the person use the computer?

CCleaner, I’ll just pull again, “once a week,” out of the air. It is one of those things where I don’t run it in a regular fashion. I run it when I have a problem – or what I consider to be a reason to run it.

So in my case, that happens to be very rarely. And in fact, for most people whose computers I set up, I also don’t recommend that they run it on a regular basis. For most people, the manual running of CCleaner isn’t necessarily a simple thing.

It is possible to do damage with CCleaner in addition to cleaning things up. So that’s one of those judgment calls. I’ll say I’d probably put it on their machine to have it, if needed – but I’ll actually not recommend that it be run on a regular basis. Again, your mileage may vary. Your users may vary. How they use their computers may vary, but those are the kind of rules of thumb that I throw out.

What Leo runs

So to be break it down once again what I do on my own machine is:

  • I run Microsoft Security Essentials – which is one anti-virus and one anti-spyware tool and then I actually don’t run anything else on any regular schedule.

  • MSE does a nightly scan; keeps itself updated – nightly at least and that’s good enough if you’re computer savvy, if you’ve got a good head about what’s going on.

  • If I need extra tools, the tools that I reach for then are things like Malwarebytes and CCleaner (as needed) to do cleaning up.

You may want to run more things and that’s fine, but it’s really hard to throw out a good rule of thumb.

(Transcript lightly edited for readability.)

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10 comments on “How often do I need to run complete anti-malware scans?”

  1. Think MSE is crap as recent studies have showed.No scanner is 100%, so only option is to run several. and then not 100%. so develop a nose for it. For me it is always an image backup that I hopefully trust.

  2. Malwarebytes blocking message keeps popping up frequently, informing me that it’s blocking uTorrent and that’s an annoyance. I’ve put in “ignore”, but does not always work… I now have IOBot AntiMalware and am happy with it…. I use uTorrent to view subtitled movies (I am deaf).

  3. Hi Leo.

    When I hear horror stories about people ‘breaking’ Windows with CCleaner, I always find that they’ve gone through the list of options and marked all or most options.
    CCleaner is a good tool, when you use it in a safe manner. When I put it on a novice user’s machine, I leave all options as they are by default, except one. I UN-mark the ‘Empty Recycle Bin’ option.
    The other options are used for specific problems, and just running them all will break Windows.

  4. Having tried Norton, and then McAfee, I now have BitDefender installed – I had read that it was “The Best”.

    However, recently I have been plagued by ads appearing in Internet Explorer – particularly ads for iLivid – which have made I LIVID indeed !

    So I asked Google, who suggested

    and also suggested SpyHunter – and this found:-

    Claro-search – 3 infections
    ad_yieldmanager – 6
    adbrite – 2
    Atlas DMT – 10
    Atwola – 2
    CasaleMedia – 6
    DoubleClick – 1
    Media – 23
    Serving-sys – 3

    a total of 56 infestations !

    Is this because BitDefender is not what it’s cracked up to be? or is not doing its job? Or am I not running it often enough ? I just left it at the default settings.

    I have now cleaned all those instances off (by hand), and SpyHunter shows a clean bill of health.

    But what is curious is that iLivid does not appear on the list at all! Nor can I find ANY file or folder with iLivid in the name!

    AND… iLivid ads still appear :-(

  5. CCleaner works perfectly well and harmlessly out of the box, indeed. Its registry-cleaning facility is also properly configured by default, offering backups in case something went wrong. As long as the user does not touch the settings without reading the manual first and understanding what it says, CCleaner is as safe as can be.

    Where security is concerned, it may provide a useful service by wiping free disk space on demand, thus disposing of traces of potentially damaging data.

  6. CCleaner out of the box deletes all cookies, including those that remember my name and password for particular sites, even if those sites are pretty much guaranteed harmless (e.g., the New York Times). Resetting them is a major PITA.

  7. KRS: Deleting all cookies on browser closure, let alone on demand with CCleaner, is nothing but conducive to security. There is convenience, and there is security – two different things altogether. Resetting? Re-entering, perhaps; otherwise there is more problems than one.

  8. “Any tool, in the hands of a fool, can be dangerous.”

    That said, before tackling any task on your computer, read up about the process and understand what you are doing first. When it comes to fixing problems regarding viruses and malware, simply downloading, installing and running every program out there may end up doing you more harm than good. And don’t take the advice of someone just because so-and-so said they are a computer guru or whatever.

    There are lots of resources available on the web. Ask Leo for one, and so many more…and don’t be afraid to get a second or third opinion. And educate yourself. YOU are the most important part of an anti-malware regimen, and if YOU are out of date, even the best software won’t be much good in protecting you.

    I follow a schedule similar to Leo’s, with anti-virus/malware running resident (Avast free) plus I also run Malwarebytes resident as well. With its real-time monitoring, it’s definitely worth the small one-time cost.

    Remember: No single anti-virus/security tool handles everything. And the most important thing you can do to protect your data…back it up with at least 2 separate sets.

  9. Does my pc have to be on to run a scan or can it scan while off? Should i set win defender and malware to run at times i am asleep and my pc is or is not?

  10. @Jeff
    Your computer needs to be on to scan it for viruses. A good time to do this is while you are sleeping. I have Microsoft Security Essentials, Malwarebytes Antimalware and Macrium backup set to run automatically at night when I’m asleep. According to this article, the daily Malwarebytes scan may be overkill, but since it runs while I’m asleep I figure, Why not?


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