WHAT EXACTLY IS A VIRUS? IS A “WORM” ALSO A VIRUS?

Viruses are computer programs or scripts that attempt to spread from one file to another on a single computer and/or from one computer to another, using a variety of methods, without the knowledge and consent of the computer user. A worm is a specific type of virus that propagates itself across many computers, usually by creating copies of itself in each computer’s memory.
Many users define viruses simply as trick programs designed to delete or move hard drive data, which, strictly speaking, is not correct. From a technical viewpoint, what makes a virus a virus is that it spreads itself. The damage it does is often incidental when making a diagnosis.


Obviously, any incidental damage is important, even when authors do not intend to create problems with their viruses; they can still cause harm unintentionally because the author did not anticipate the full effect or unintentional side effects. The most common method used for spreading a virus is through e-mail attachment. Sending a virus, even if designed to be harmless, can cause unforeseen damage.

Viruses and Worms

The term virus has long been used generically to describe any computer threat, but in actuality it refers specifically to malware that inserts malicious code into existing documents or programs, and then spreads itself by various means.

The reason people often call every computer threat a "virus", is because viruses are the original type of malware, actually predating the public Internet. Today, viruses are still by far the most common type of network security threat, and over 90 percent of viruses are spread through attachments on emails. Often the attacker will combine a virus with a "zombie" attack (discussed below) so that you will receive an email with an attachment from a friend that actually contains a virus.

Prevention
The good news about viruses, is that they require a user action to insert themselves onto your computer. So, training your office staff to never open an email attachment that they weren't expecting, no matter who the sender is, will go a very long way to keeping your network free of viruses. Unfortunately, educating your staff about what attachments to open will do little to stop worms from infecting your network. That is because although worms are also often initially delivered in email, they don't need a host file (i.e., no attachment is needed for an email to be infected) and they can propagate themselves. Worms, unlike viruses, spread on their own. So once a computer is infected, the worm can often make quick copies of itself and infect an entire network within a few hours. Because of this unique opportunity to multiply themselves quickly across a network, worms are responsible for a good number of companies’ widespread network failures.

Both viruses and worms often work to open up new holes in your network security in order to allow even more dangerous security threats to infect your network. Consequently, it should be an essential priority of every company and individual to use virus protection software to limit the incoming malware, and then to educate employees to make sure those worms and viruses that slip through never get opened.