Virus & Worms

Virus & Worms

What is a virus?

A computer virus is a small program written to alter the way a computer operates, without the permission or knowledge of the user. A virus must meet two criteria:

It must execute itself. It will often place its own code in the path of execution of another program.
It must replicate itself. For example, it may replace other executable files with a copy of the virus infected file. Viruses can infect desktop computers and network servers alike.

Some viruses are programmed to damage the computer by damaging programs, deleting files, or reformatting the hard disk. Others are not designed to do any damage, but simply to replicate themselves and make their presence known by presenting text, video, and audio messages. Even these benign viruses can create problems for the computer user. They typically take up computer memory used by legitimate programs. As a result, they often cause erratic behavior and can result in system crashes. In addition, many viruses are bug-ridden, and these bugs may lead to system crashes and data loss.

What Is A Trojan Horse?

Trojan horses are malicious programs disguised as something benign. They've been known to pose as games, utilities, and email attachments. Once opened, Trojan horses act much differently than you expect. Some merely annoy, sending emails to everyone in your address book. Others do serious damage, to the point of stealing passwords and data files. Unlike viruses, Trojan horses are not self-replicating

Active Trojan horses are an advanced type of Trojan horse. They use unprotected ports to open lines of communication with your computer, and they can ultimately give hackers control over your machine. Active Trojan horses are also called Remote Access Trojans.

What is a worm?

Worms are programs that replicate themselves from system to system without the use of a host file. This is in contrast to viruses, which requires the spreading of an infected host file. Although worms generally exist inside of other files, often Word or Excel documents, there is a difference between how worms and viruses use the host file. Usually the worm will release a document that already has the "worm" macro inside the document. The entire document will travel from computer to computer, so the entire document should be considered the worm. PrettyPark.Worm is a particularly prevalent example.

What is a virus hoax?

Virus hoaxes are messages, almost always sent by email, that amount to little more than chain letters. Some of the common phrases used in these hoaxes are:

If you receive an email titled [email virus hoax name here], do not open it!
Delete it immediately!
It contains the [hoax name] virus.
It will delete everything on your hard drive and [extreme and improbable danger specified here].
This virus was announced today by [reputable organization name here].
Forward this warning to everyone you know!

Most virus hoax warnings do not deviate far from this pattern. If you are unsure if a virus warning is legitimate or a hoax, seek additional information from a reliable source.