Introduction to viruses, worms, and Trojan Horses

Viruses, worms, and Trojan Horses are malicious programs that can cause damage to your computer and information on your computer, slow down the Internet, and use your computer to spread themselves to your friends, family, co-workers, and the rest of the Web. The good news is that with an ounce of prevention and some good common sense you are less likely to fall victim to these threats. Think of it as locking your front door to protect your entire family.

Read on for definitions, ways to find out if you've been victimized, and solutions you can use to help make your computer safer.

What is a virus?

A virus is a piece of computer code that attaches itself to a program or file so it can spread from computer to computer, infecting as it travels. Viruses can damage your software, your hardware, and your files.

Virus (n.) Code written with the express intention of replicating itself. A virus attempts to spread from computer to computer by attaching itself to a host program. It may damage hardware, software, or information.

Just as human viruses range in severity from Ebola to the 24-hour Flu, computer viruses range from the mildly annoying to the downright destructive. The good news is that a true virus does not spread without human action to move it along, such as sharing a file or sending an e-mail.

What is a worm?

A worm, like a virus, is designed to copy itself from one computer to another, but it does so automatically by taking control of features on the computer that can transport files or information. Once you have a worm in your system it can travel alone. A great danger of worms is their ability to replicate in great volume. For example, a worm could send out copies of itself to everyone listed in your e-mail address book, and their computers would then do the same, causing a domino effect of heavy network traffic that would slow down business networks and the Internet as a whole. When new worms are unleashed, they spread very quickly, clogging networks and possibly making you wait twice as long for you (and everyone else) to view Web pages on the Internet.

What is a Trojan Horse?

Just as the mythological Trojan Horse appeared to be a gift, but turned out to contain Greek soldiers who overtook the city of Troy, today's Trojan Horses are computer programs that appear to be useful software, but instead they compromise your security and cause a lot of damage. A recent Trojan Horse came in the form of an e-mail that included attachments claiming to be Microsoft security updates, but turned out to be viruses that attempted to disable antivirus and firewall software.

How do worms and other viruses spread?

Virtually all viruses and many worms cannot spread unless you open or run an infected program.

Many of the most dangerous viruses were primarily spread through e-mail attachments—the files that are sent along with an e-mail message. You can usually tell if your e-mail includes an attachment because you'll see a paperclip icon that represents the attachment and includes its name. Photos, letters written in Microsoft Word, and even Excel spreadsheets are just some of the file types you might receive through e-mail each day. The virus is launched when you open the file attachment (usually by double-clicking the attachment icon).

Tip: Never open anything that is attached to an e-mail unless you were expecting the attachment and you know the exact contents of that file.

If you receive an e-mail with an attachment from someone you don't know you should delete it immediately. Unfortunately, you're no longer safe opening attachments from people you do know. Viruses and worms have the ability to steal the information out of e-mail programs and send themselves to everyone listed in your address book. So, if you get an e-mail from someone with a message you don't understand or a file you weren't expecting, always contact the person and confirm the contents of the attachment before you open it.

Other viruses can spread through programs you download from the Internet or from virus-ridden computer disks that you borrow from friends or even buy in a store. These are less common ways to contract a virus. Most people get viruses from opening and running unknown e-mail attachments.

How can I tell if I have a worm or other virus?

When you open and run an infected program, you might not know you've contracted a virus. Your computer may slow down, stop responding, or crash and restart every few minutes. Sometimes a virus will attack the files you need to start up a computer. In this case, you might press the power button and find yourself staring at a blank screen.

All of these symptoms are common signs that your computer has a virus—although they could also be caused by hardware or software problems that have nothing to do with having a virus.

Beware of messages warning you that you sent e-mail that contained a virus. This may mean that the virus has listed your e-mail address as the sender of a tainted e-mail. This does not necessarily mean you have a virus. Some viruses have the ability to forge e-mail addresses. You might hear this referred to as "spoofing."
Unless you have up-to-date antivirus software installed on your computer, there is no sure way to know if you have a virus or not.

If you don't have current antivirus software or if you're interested in installing a different brand of antivirus software, read our tips for reducing your virus risk.

Next steps to improving your computer's security
Keeping your antivirus software up to date is just the first step toward safer surfing online. You can continue to improve your computer's security by keeping your software up to date and using a firewall

Next Steps: How to improve your computer's security
Nothing will guarantee the security of your computer 100 percent. However, you can continue to improve your computer's security by keeping your software up to date and maintaining a current antivirus software subscription.

AT THE SIDE:
1: Help Protect Yourself Against Viruses, Worms, and Trojan Horses

Although viruses, worms, and Trojan Horses have very different characteristics, there are three main ways you can help protect yourself against all of them.
     Step 1: Never open an e-mail attachment from a stranger.
     Step 2: Never open an e-mail attachment from someone you know, unless you know exactly what the attachment is.
     Step 3: Always keep your antivirus software up-to-date.
     Step 4: Keep your Microsoft software current using our online resources

2: Protect your PC
3 steps to ensure your pc is protected
     1) use an internet firewall
     2) Get computer update
     3) Use up-to-date antivirus software

Reduce your virus risk with updated antivirus software

A virus is a program that can wreak havoc on your computer and use your Internet connection to spread itself to other computers, usually those of your co-workers, friends, and family. You can prevent many viruses by only opening e-mail attachments when you know where the e-mail came from and what the attachment is. Unfortunately, sometimes that isn't even enough. Read on to learn how you can help prevent viruses from infecting your computer.

Step 1: Check your computer for antivirus software

Most computers now come with antivirus software installed. Follow these steps to determine if you already have the software you need to prevent viruses.

1. Click Start, and then click Programs.
2. Look for the word "antivirus." You might also see the name of a popular antivirus manufacturer such as McAfee, Norton, Trend Micro, E trust, or Symantec.

Step 2: Keep your antivirus program up to date

You don't expect that flu shot you got three years ago to prevent you from contracting this year's strain do you? Similarly, antivirus software will only help protect you from viruses if you update it regularly. Antivirus programs work by comparing your machine against known viruses. When you update your software you download information about all the latest viruses. Depending on your software this information is usually referred to as "virus definitions." As virus writers are always coming up with new ways to infect your computer, we recommend that you download all the new virus definitions monthly or even weekly.

Here are two ways to find out when you last updated your antivirus program:

1. Click the antivirus software icon in your system tray in the bottom right side of your screen, near the clock. You should see the date that you last updated your software.
2. Open your antivirus software by clicking Start, clicking Programs, and then clicking your antivirus software. Look for information about the update status.

If it has been more than a month since you updated your software, do it now to help ensure your safety. You can usually download up to date virus definitions (antivirus software updates) by simply visiting the website of the company that makes your software.

Remember, you must have a current antivirus subscription to download updates to your software. If your subscription has expired, be sure to renew—or, if you prefer, take this opportunity to try a different antivirus program.

Tip: Many antivirus companies offer an automatic downloads service that will automatically update your antivirus software when you go online. Check your antivirus manufacturer's website for more information.

Step 3: Choose antivirus software that's right for you

If you don't have antivirus software on your system, or if you'd like to install a different program here are two key factors to consider before you make your choice:

•  Auto-updates. Downloading the latest updates is critical. Many companies offer an automated option for their products.
• The manufacturer's reputation. If you search the Internet long enough you're bound to find antivirus software for which you don't have to pay a dime. Yet other antivirus vendors allow you to download a free trial version of their antivirus software to see if you like it before you buy it.

Tip: Two antivirus programs are not better than one. If you already have antivirus software but you'd like to try a different one, always uninstall the old program before you install the new one. Running more than one antivirus program at the same time may cause major conflicts.

AT THE SIDE

All good antivirus software should have an auto detect mode, which means the software is always running and will automatically scan files when you download them, open them, copy them, or run them.

When you configure your software for the first time you'll probably be given the opportunity to turn this setting off so that in the future you'll have to remember to manually scan for viruses every time you open a new file. We do not recommend this.

You're much safer keeping your antivirus program on auto detect.


Antivirus Software Vendors


  •   Computer Associates

  •   F-secure

  •  McAfee Security

  •   Symantec

  •   Trend Micro

Windows Security Updates help you to protect your computer form Virus, worm and Trojans

Security updates help shield your computer from vulnerabilities, viruses, worms, and other threats as they are discovered. If you are using Microsoft Windows® 2000 Service Pack 3 (SP3) or later, you can use the Automatic Updates feature to download the latest Windows security updates automatically when your computer is on and connected to the Internet. If you are not sure if you have the latest Windows 2000 service pack installed check your operating system version.

Click Start, Click Run, write winver it will display your current version of service Pack

Important: To ensure you have all the latest updates available from Microsoft, be sure to visit Windows Update after turning on the Automatic Updates feature. Automatic Updates only downloads future updates. It does not download existing updates available for your computer. (We'll give you the full details in the second half of this Step.)

Turn on the Automatic Updates feature

        1.       Click Start, point to Settings, and then click Control Panel.

2.       Double click Automatic Updates.

3.       Click the Automatic Updates tab, and then select Keep my computer up to date.

4.       Select a setting. Microsoft recommends selecting Automatically download the updates, and install them on the schedule that I specify and setting a daily schedule.

Choose Automatically download the updates and
install them on a schedule that I specify

Note: You can set the Automatic Downloads feature for any time of day. (To avoid slow-downs, we recommend a time when you will not be using the computer for other Web or e-mail tasks.) If you set up Automatic Updates to notify you, or if you forget to leave your computer on, you will see a notification balloon. Click the notification balloon to review and install the updates.

You will now download all future updates automatically.
Next, get up to date with Windows Update
Here's how you can bring your computer up to date with security updates that are currently available. You can also use these instructions to keep up with the latest non-critical updates:

1. Go to the Windows Update Web site at http://windowsupdate.microsoft.com.

2. On the Windows Update site, click Scan for Updates. Windows Update will scan your computer and displays a pre-selected list of critical updates, including security updates and service packs.

Click Scan for updates

3. Note: Slower modems might take several hours to download all recommended updates the first time you use Windows Update. Download times might vary depending on modem speed and how many updates your computer needs. To reduce download times, run Windows Update when you are not using your computer for other Internet-related tasks such as reading e-mail or surfing the Web.

4. In the Pick updates to install click Critical Updates and Service Packs. Windows Update then creates a list of updates that are appropriate for your computer.

5. Click Review and install updates.

6. Select updates to install and then click Install Now. You might have to to restart your computer after installing the updates.

7. Note: Be sure to go back to Windows Update after installation to check for any additional updates. You might have to do this several times.

Important If you use Microsoft Office, visit the Office Update site to install the latest security releases.