Virtualization is a pretty exciting new technology, but it can be easy to forget that you've got to protect your VMs the same way you protect a physical machine—your host machine's antivirus and antispyware software may not be enough to stop the VM from getting infected. And there's a good chance that the license for your host's protective software doesn't let you install it in a VM.
Microsoft released a beta of its free Security Essentials late last month. You can install as many copies of Security Essentials as you'd like, as long as you're installing it on genuine copies of Windows. MSE doesn't have any central management capabilities so you probably won't want to use it on end user machines in an enterprise environment, but it's free and has a small footprint, so it's a good choice for VMs.
I installed Security Essentials in a Windows 7 VMware Workstation VM. The installation took less than two minutes and its real-time protection didn't have a noticeable impact of the VM's performance. How well did it protect the VM? It's hard to say, because I'm not about to go hunting down viruses on a computer I need to use daily, but Security Essentials immediately detected the EICAR test file.
There are plenty of free antivirus packages out there, some of them with very good reputations, so make sure you know your options. If you just need a quick download from a trusted company to protect a VM, however, it looks like Security Essentials will be a good choice.
You can learn more at the Security Essentials site. The beta isn't currently accepting more users, but it's expected that the final version of Security Essentials will be available before the end of the year.
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