Make sure system software is up-to-date. Most cyberattacks take advantage of known flaws in the computer's operating system and included software. Unfortunately, our data indicates that we still see that up to one-fifth of systems in the U.S. are using outdated software, with the ratio in other countries as high as 50 % of all systems. Software manufacturers publish software updates, or patches, and it is straightforward to apply those updates. If they are running Windows, have them check by clicking "Start," then "Windows Update." If they are running Mac OS X, have them click on "Software Update..." in the Apple Menu.
Once the system is updated, focus them on the browser. Modern browsers come with "plug-ins" that extend its capabilities to play music, videos, and games. These plug-ins are not included in the system update process, and that makes them fall behind in updates. They serve as prime candidates for attacks by malware. You need to make sure they are running the latest level of plug-in software. We have developed a free, easy-to-use, quick service for that purpose called BrowserCheck. It knows about Windows and Mac OS X and supports all major browsers. Simply have them go to here to BrowserCheck and follow the steps provided by the service to make sure the browser and plug-ins are up-to-date across the board.
Next, have them install antivirus software on their PCs or Macs. AV software provides an additional level of security for the system. It has the same function as a yearly flu shot and provides protection against well-known viruses. There are a number of free tools for PCs, including an offer from Microsoft called "Security Essentials." For Macs, Sophos recently made its AV available to end users for free. Another source of free AV can be the Internet service provider (ISP). For example, I get my Internet access through Comcast, which provides a free copy of an AV program (Symantec's) for both PCs and Macs at its security page. Check with the ISP, look for its security page, and take advantage of its offer.
One last thing: I have started to switch everybody to the free DNS services provided by OpenDNS. I usually reconfigure their home routers to use the OpenDNS nameservers, and they gain instant protection against a whole class of well-known malware threats. OpenDNS integrates several popular domain blacklists that identify known malware sites and implements filtering on the DNS server level without any necessity of appliances or firewall modifications.
-- As the CTO for Qualys, Wolfgang Kandek is responsible for product direction and all operational aspects of the QualysGuard platform and its infrastructure. Wolfgang has more than 20 years of experience in developing and managing information systems. His focus has been on Unix-based server architectures and application delivery through the Internet. Wolfgang provides the latest commentary on his blog: laws.qualys.com and also publishes his Patch Tuesday commentary to the QualysGuard channel: www.youtube.com/QualysGuard. He is a frequent source in business and trade media and speaks at industry conferences around the world, most recently at RSA 2010.