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How to Protect Your Computer From Viruses and Malicious Software
Author: Eldon Martin
Updated: 18-May-2006 

Malicious software, or malware,  is likely the most widespread problem faced by computer users today.   As a computer technician, I find that about three out of four jobs I do for home computer users are to remove malware in one form or another.

Malware programs come in several forms: Spyware and adware track your activities when surfing the Internet and bombard you with pop-up advertisements. Hijackers change browser start pages and redirect you to unwanted web sites.  Viruses and trojans erase data and allow hackers to access your files.  In many cases, the end result is that your computer becomes unusable and in need of repair.

Many computer users try to protect their computers by installing anti-virus and firewall programs.  While these programs are of value, they alone are not sufficient to fix and prevent all types of attacks. Many computers with up-to-date anti-virus and firewall software arrive at my door infested with malware to the extent that they are unusable.

Without taking the appropriate measures and precautions, even a brand new or recently cleaned computer can be infested with malware and unusable within days.

I have found user education to be the most effective deterrent to malware.  Here is a list of things you can do to keep your computer healthy:

1. Be skeptical of free software

There are many free software programs available on the Internet.  Unfortunately, many of these are bundled with malware designed to display pop-up ads or monitor your browsing activities.  Some even go further by regularly downloading additional malware without notifying you. 

Here are some common examples of free software that can contain malware:

            Screen Savers                                            AIM Buddy Icons
            Desktop Background Pictures                    Email “Smileys”
            Music-Sharing Services                              Online Games

Many troublesome adware programs are legal because they explain what they do in the license agreement, which the user typically must agree to before the program is installed.  If you're not sure about a program, it pays to glance over the license agreement.  You may be surprised what you are giving permission for. 

You should also be very skeptical of spyware removal tools and pop-up blocker programs.  Believe it or not, many of these tools actually contain adware and spyware themselves.  If you're not completely sure about a piece of software, ask a savvy computer user or technician before installing it.  

There are some good freebies on the Internet, but there are many undesirable ones as well.  To protect you computer, you must exercise discretion. Be very cautious about giving a web site permission to install software on your computer. A hacker with $20 and some spare time can construct a professional-looking web page that is designed to install malware on your computer. If you want to download music, stick to reputable names like napster.com or Yahoo! Music Unlimited.  For online gaming, Yahoo! Games is a good choice. Some parents have found it necessary to forbid their children from downloading any software without permission.


2. Install all Microsoft critical updates

Many malware programs have the ability to infect your computer only because of a mistake made by Microsoft during the development of Windows or Internet Explorer.  When Microsoft learns of these mistakes, it releases updates to fix them.

The well-known “Blaster” and “Sasser” worms  infected millions of computers, all of which didn't have the latest Windows updates installed. Thanks to mistakes made by Microsoft, these and other viruses could infect computers without any action on the part of the user other than connecting to the Internet. Computers kept up to date were not effected.

If your computer was recently serviced by Great Cove Technologies and is running Windows XP, the automatic update feature will be enabled.  This will cause the computer to automatically download and install important updates. To find the automatic update option, click Start, RIGHT-click My Computer, click Properties, and then click the Automatic Updates tab. 

If you are using an older version of Windows, or if you'd like to install the updates manually, visit windowsupdate.microsoft.com or click on Start > Windows Update (if you're using Windows XP, it will be found under Start > All Programs > Windows Update). You should install any “recommended” or “critical” updates.  Other updates are optional and can be ignored.

There is a small amount of risk involved in downloading Windows updates.  I've had a handful of customers who experienced various problems after installing a recommended update.  However, these cases are very rare, and several times a week I find myself fixing a computer because updates were not installed.


3. Don't open suspicious email attachments

One of the most common ways for viruses to spread is through the use of email attachments.  Under usual circumstances, it is OK to read the text of an email that contains a virus. Your computer will not be infected unless you make the mistake of attempting to open the attachment.  Although some viruses can infect even without the use of an attachment, this is normally not a problem if you keep your software up-to-date as described earlier in the article.

Most people follow a simple rule that they assume will protect them:  They do not open any attachment unless they recognize the sender.  However, knowing the sender does not make an attachment safe.  In fact, many viruses appear to be sent by somebody you know. Every day people are infected with viruses because they open an attachment on an email that appeared to come from a family member or close friend.  Before you open a file attached to an email, make sure BOTH of these statements are true:

1.You know the person who is sending the email.
2.The email contains a personal message that describes the attachment and makes it clear the message was written by the person it appears to be from. A one line message like “open this, it's cool!” is not enough because many viruses are designed to automatically generate such messages.

If the message is vague as to what the attachment is, email or call the sender to see if they intended to send it to you.

4. Consider using an alternative web browser

The computer program that you use to look at web pages on the Internet is called a web browser.  Microsoft Internet Explorer is the web browser that comes packaged with Windows, and is therefore used by the vast majority of computer users.  Contrary to many people's assumptions, there are a handful of other free Internet browsers that meet or even exceed the ease of use and features of Internet Explorer. 

Many viruses and other malicious software on the Internet infect computers by taking advantage of security vulnerabilities or “holes” in Internet Explorer.  While keeping Internet Explorer up-to-date as described earlier in the article provides some protection, many security experts are recommending that users abandon Internet Explorer altogether.  Even the U.S. Government's own CERT (Computer Emergency Readiness Team)  has recommended this in a June 2004 alert.

One of the most promising alternative browsers is called Mozilla Firefox, a free product that is quickly gaining popularity.  In addition to providing a safer browsing expirience, Firefox also automatically blocks advertising pop-ups triggered by the websites you visit. Of course, you'll want to keep whatever browser you use up-to-date, as security problems are discovered even in non-Microsoft browsers. Firefox automatically installs updates when they become available.