Online Anti-Virus Scans: A Free Second Opinion
Brian Krebs on Computer SecurityOnline Anti-Virus Scans: A Free Second Opinion
Periodic online virus scanning is a good idea for Windows users, even for people already using up-to-date anti-virus tools. There are a couple of reasons I suggest this: First, anti-virus software is frequently slow to spot new threats. Take a gander at the daily "unrecognized" stats posted by Shadowserver.org, which tracks the performance (or lack thereof) of several popular tools in spotting new variants. That list currently examines the performance of several free programs, but the reality is not much different with the commercial tools. Just have a look at performance metrics and virus detection failure rates chronicled here (virustotal.com) and here.
The second reason follows from the first: If something nasty does make it past your security defenses, usually the first thing it will try to do is disable the active protection and update features in those tools. In such cases, you probably would not know about the infection unless you turned to a third-party program that is not already installed on your computer.
In my experience, two of the better free online anti-virus scanners are Panda Software's PandaScan and Kaspersky Lab's Free Virus Scan. Both require that you run the scans using Internet Explorer, as both require the installation of an ActiveX plug-in to do the job.
F-Secure Corp., CA and BitDefender also offer free online scanners that also use IE and ActiveX, but I haven't yet tried those so I can't offer an opinion on them.
TrendMicro's HouseCall service lets you install and run a free scanning tool from inside an IE or Firefox browser. However, I found the program both annoying -- it emitted a series of very loud and startling tones through my computer speakers while downloading virus definitions -- and ineffective. It crashed halfway through the scan, taking all of my other open Firefox windows with it, including an earlier, unsaved version of this blog post. (I had hoped Firefox 2.0's crash-recovery feature would save what I had typed as it had in previous crashes, but no such luck this time.)
If you have just a single file or archive that you'd like to scan, I'd suggest submitting it to VirusTotal, a free online anti-virus engine that will scan your submission against more than two dozen of the most well-known tools.
Depending on the speed of your PC and the number of files and hard drives you have, conducting an online scan can take between a few minutes to several hours to complete. It's not a bad idea to run the scan only when you can afford to be away from the PC for a few hours, or perhaps right before bedtime. Even on my test machine -- which sports a 2.2 GHz processor and 2 gigabytes of memory -- running several of the online scanners interfered with the simplest of tasks, such as composing an e-mail.
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