Malware comes in a variety of forms, though the most common and well known are viruses, spyware and adware. Each poses a unique threat but can easily be prevented by installing anti-virus and anti-malware software, of which there are a number of excellent free programs.
Windows
There are two programs that are highly advisable to install and run on your computer. If you are using a fresh installed copy of Windows it is acceptable to install your anti-virus software first. However, if you have not been using an anti-virus program you might like to install and run anti-Malware software first to clear anything out that may prevent your anti-virus software installing or working properly.
I am a Mac user myself, but have tested MalwareBytes Free and AVG Free on Windows systems and have found them acceptable. MalwareBytes does not provide ongoing protection but is an effective cleaning tool, while AVG has sometimes proven less reliable at ridding systems of malware but excellent at identifying theirpresence. Together they will provide sufficient coverage.
Link to AVG Free Download (Requires registration information but this does not have to be verified. Feel free to sign up as Michel Souris)
Mac
There has been constant debate about the need to use antivirus software on Macs due to the low incidence of infection and lack of Mac-specific malware. However, there are two good reasons to use anti-virus and anti-malware software on your Mac: firstly, it will prevent infection if someone does write a Mac-specific program; and it may stop you from acting as a carrier and spreading viruses to your friends’ Windows computers. I have been using ClamXav and have found it to work quite well, even if the interface is a little clunky. Sophos is highly recommended and may prove more useful for less experienced users.
NB: The Mac OS X 10.8 update included a new feature called Gatekeeper which prevents users from installing software not approved by Apple and available through the Mac App Store. The requirements for software to be made available through the Mac App Store are quite restrictive, to the point that there are two versions of ClamXav available for download. The version downloaded from the website has full functionality while the Mac App Store version prevents ClamXav from running its Sentry function (real-time protection). This is quite a substantial flaw and I would recommend turning Gatekeeper off:
- Access the Gatekeeper settings in System Preferences > Security & Privacy > General.
- Click on the lock on the lower left of the window and type in your system password.
- To install other apps, select the option to install from Anywhere.
For additional security, Gatekeeper can be temporarily disabled to allow you to install and launch new software. If Gatekeeper is turned on again after a program’s initial launch it should still continue to function.
Firewalls
A firewall prevents attackers from accessing your computer or computers on your network via the Internet. Some firewalls incorporate network monitors and rulesets that allow you to see whether programs are accessing your network or the Internet and what they are connecting to and whether external servers are trying to connect to your computer. This is very useful for detecting if you are under attack from a hacker or if some of your software is “dialing home” or otherwise acting suspiciously and then blocking out the hacker or that software. The most effective software I have found is Little Snitch, which is only available for Mac and requires a paid license (unless you can find an illegal copy somewhere). When set to use custom rules and frequent pop-ups, Comodo Firewall performs a similar function and is very useful for learning exactly what your programs are doing when they run.
For programs that regularly use the Internet it is acceptable to allow all connections, or else you will go insane from the dozens of popups that will appear every time that you try to do something.
Link to COMODO Firewall (Windows)