How did my computer become infected with a virus?

If you think you're savvy enough to avoid computer viruses, think again. Even the most secure machine can become infected and some of the methods modern day hackers use to gain access to your computer may surprise you.

How are viruses spread?

When computer viruses began, the most common method for spreading was either through a compromised floppy disk or as attachments on message boards which were growing rapidly in popularity.

Today, the possibilities for infection are many but hackers are primarily creatures of habit who still frequent the most popular internet sites and email.

Infected disks and usb drives are both popular ways for viruses to spread. An infected disk can travel to several machines on several different networks. For example, a disk used at work could be taken home and/or used in someone else’s office. If you consider how many different machines the average office workers comes in contact with daily, it is easy to see how this method remains effective.

However, network distribution is more efficient. Most computers are now permanently connected to a network whether it is a company network or a broadband connection at home. If one computer on the network is not properly secured with antivirus software and a firewall, this machine can host and distribute a virus to every machine on the same network. One example of this includes instant messenger programs such as MSN, Yahoo or AOL. When a user signs in, they become a part of that network and viruses can be sent through these programs.

Art of disguise

Another common method for a virus to gain access to your machine is by disguising itself as a legitimate piece of software. This can be done by creating a link on a webpage or through file sharing networks such as Limewire or Gnutella. Viruses are often renamed as files that are popular search topics such as an mp3 or a commonly used software program. These files are either masquerading and contain nothing more than the virus or they can be actual copies of the legitimate file altered to include a virus. Once you play the music or run the installation, the virus would then deploy and infect your computer.

Viruses can also be loaded on to your machine when you visit an infected webpage. Though this method is not as common due to increased security efforts of websites owners, it can happen. Anyone who is searching for discounted or free versions of well known software titles such as Adobe Photoshop or Dreamweaver should think twice. The hackers who distribute these titles for free usually have another agenda. At the least, they may load a piece of software known as a ‘Trojan’ to steal your personal data but at worst they could load viruses that can destroy your hard drive. It is estimated that over 75% of website viruses are found on hacker run sites.

User participation

Despite the lingering memory of the 'Melissa' virus which struck millions of computers, email remains an easy method for infection. However, emailed viruses require some user participation in order to deploy. If an infected email reaches your inbox, it might contain an attachment that must be opened in order to launch the virus, or it might be coded into the email and would simply require that a user opens or reads it. This can be particularly troublesome if you use a reading 'preview' pane in your email program. Simply clicking the email to view the text would then launch the virus on your system.

With hackers inventing ever more sophisticated viruses, it's important to take precautions to reduce the risk of your computer becoming infected.

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Anti-virus software