Free anti-virus programs
There are uncountable antivirus programs available on software market. Most of them are commercial programs that require yearly subscription fee, but there are also several free anti-virus tools available for home users. Free does not necessarily mean limited protection or annoying pop-ups about buying commercial equivalent.
A free antivirus program should:
- work at all times - provide resident (real-time) protection, not just do manual scanning
- update virus and malware definitions automatically
- scan files both on your computer and files coming from your home network or the Internet
- scan e-mails and attachments
- scan instant messaging traffic (Skype, Yahoo Messenger, etc)
- provide basic protection from malware and rootkits
- be compatible with Windows XP, Vista, 7 and 8/8.1
Please remember that you should have only one real-time virus protection program installed at all times. Having more than one anti-virus working at the same time makes your computer very slow!
My first choice - Avast Free Antivirus
Avast Free Antivirus meets all requirements above plus it scans P2P (file sharing programs - eMule, Soulseek, BitTorrent, etc) traffic and it is able to detect hidden web threats such as drive-by downloads. It also has a pretty good rootkit detection module, provided by Gmer.
Avast Free Antivirus 2015 (aka version 10), released in October 2014, includes Smart Scan feature and Home Network scanning (testing routers for weaknesses and infections).
It does require registration upon first installation and once every year afterwards, but that is not difficult. Avast Free Antivirus does not consume too much resources and it can do scheduled scanning and boot-time scanning.
I recommend Avast for computers that are no more than 5 years old and do not feel very slow already.
My second choice - Microsoft Security Essentials
Microsoft Security Essentials (aka MSE or MSSE) provides good overall protection for home users and for small businesses with less than 10 computers (make no mistake - its licensing terms prohibit using the software in larger commercial environments!). It is meant to be a replacement for traditional Windows Defender in Windows Vista and 7.
Version 4.5 (Microsoft skipped version 3 and released version 4 in April, 2012 and 4.5 in April, 2014) of MSE does a good job at detecting viruses and malware plus it is very easy to use and configure. There are only a few minor changes to user interface compared to version 2, but Microsoft claims that cleaning process is better and faster now.
Windows XP users cannot install MSE after April 8th of 2014, and existing users should be aware that Microsoft will stop providing malware definition updates after July 14, 2015. Because outdated definitions cannot provide adequate protection, scroll up for Avast Free Antivirus instructions.
Windows Vista and 7 users will continue receiving MSE updates as usual.
Microsoft Security Essentials is not resource-hungry and it is able to scan your computer on scheduled basis, but it can't do a boot-time scan. You can still use the program in Safe Mode, though.
MSE is recommended for older and slower computers.
Please note that you cannot install Microsoft Security Essentials in Windows 8/8.1, because nearly identical Windows Defender is included by default.
Included in Windows 8 and 8.1 - Windows Defender
Windows Defender in Windows 8 and 8.1 is very similar to Microsoft Security Essentials - it provides continuous protection from viruses and all other types of malware. Do not mix it up with Windows Defender in Windows Vista or 7 where the program scanned for spyware only!
While configuration and usage of Windows 8/8.1 Defender is nearly identical to that of Microsoft Security Essentials, it lacks several useful features, such as context menus is File Explorer (right-click scanning of selected files or folders), Taskbar Notification area (System Tray) icon, scheduling scans in GUI (Graphical User Interface) and setting default actions for different threat levels.
You can still use the command-line version called MpCmdRun for scheduled scanning and scanning of custom items.
In Windows 8.1, Defender adds high-performance behavior monitoring that helps in identifying and cleaning unknown threats. The feature sends activity logs of suspicious actions to Microsoft automatically, so that an updated virus signature database can be created.
Windows 8.1 version of Defender always performs a quick scan shortly after signing in to an account.
Most users should be satisfied with Windows Defender in Windows 8/8.1, but if you require more control, use Avast Free Antivirus instead.
If your security software fails
There is not even a single free or paid anti-virus product out there that can detect and remove all viruses and malware, or that is bullet-proof. This is because hundreds and even thousands of new malware variants appear every day.
Always use free anti-malware program as a companion to your AV protection. Malwarebytes Anti-Malware is a good tool that is able to clean your PC from very nasty rootkits.
And then there are times when some malware disables or impairs your security software. In such cases, use free RKill that detects and stops (but does not remove!) active rootkits, Trojans, worms, etc. After the quick (up to 5 minutes only!) scan completes, your anti-virus and anti-malware should be able to run again and they can probably remove the malware.
SmartScreen in Windows 8 and 8.1
While Windows SmartScreen is not exactly a virus and malware protection, it helps in stopping unknown threats in Windows 8/8.1. It is similar to SmartScreen Filter in Internet Explorer that checks web page reputation, but it checks application reputation instead.
For example, if you download a program that has never been seen before by the huge SmartScreen database, you will encounter a warning that still allows you to run the program if you are 100% sure it's safe. This helps in stopping attacks by malicious programs that try to look like legitimate programs - fake Adobe Flash Player installers are very common examples of this.
If SmartScreen detects a known threat before your antivirus program, it stops the installation.
To manage SmartScreen, open Settings Search using keyboard shortcut Windows Key+W, type "smartscreen" into Search box and click Change SmartScreen settings.
Touch screen users should first swipe in from the right edge of screen to reveal Charms bar and tap/touch the Search icon.
Expand Security in Action Center or click Change Windows SmartScreen settings on the left.
In Action Center, Security section, find the Windows SmartScreen section and click Change settings.
By default, the Get administrator approval before running an unrecognized app from the Internet (recommended) option is selected. This means that only users with administrative rights can launch unknown programs. The default becomes handy if you have overly curious, but inexperienced and gullible users (kids?) on your PC.
To allow standard users to select actions for SmartScreen detections, activate the Warn before running an unrecognized app, but don't require administrator approval option instead.
Click OK after making changes.