Types+of+viruses

Type of viruses  Back
 * ||  || Computer viruses are deliberately created and sent out by attackers. A virus is attached to small pieces of computer code, software, or documents. The virus executes when the software is run on a computer. If the virus is spread to other computers, those computers could continue to spread the virus.

A **virus** is a program written with malicious intent and sent out by attackers. The virus is transferred to another computer through e-mail, file transfers, and instant messaging. The virus hides by attaching itself to a file on the computer. When the file is accessed, the virus executes and infects the computer. A virus has the potential to corrupt or even delete files on your computer, use your e-mail to spread itself to other computers, or even erase your entire hard drive. 



A **worm** is a self-replicating program that is harmful to networks. A worm uses the network to duplicate its code to the hosts on a network, often without any user intervention. It is different from a virus because a worm does not need to attach to a program to infect a host. Even if the worm does not damage data or applications on the hosts it infects, it is harmful to networks because it consumes bandwidth.

A **Trojan** is technically a worm. The Trojan does not need to be attached to other software. Instead, a Trojan threat is hidden in software that appears to do one thing, and yet behind the scenes it does another. Trojans are often disguised as useful software. The Trojan program can reproduce like a virus and spread to other computers. Computer data damage and production loss could be significant. A technician might be needed to perform the repairs, and employees might lose or have to replace data. An infected computer could be sending critical data to competitors, while at the same time infecting other computers on the network.

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 * ||  || Adware, spyware, and grayware are usually installed on a computer without the knowledge of the user. These programs collect information stored on the computer, change the computer configuration, or open extra windows on the computer without the user’s consent.

**Adware** is a software program that displays advertising on your computer. Adware is usually distributed with downloaded software. Most often, adware is displayed in a popup window. Adware popup windows are sometimes difficult to control and will open new windows faster than users can close them.



**Grayware** or **malware** is a file or program other then a virus that is potentially harmful. Many grayware attacks are phishing attacks that try to persuade the reader to unknowingly provide attackers with access to personal information. As you fill out an online form, the data is sent to the attacker. Grayware can be removed using spyware and adware removal tools.

**Spyware**, a type of grayware, is similar to adware. It is distributed without any user intervention or knowledge. Once installed, the spyware monitors activity on the computer. The spyware then sends this information to the organization responsible for launching the spyware.

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Summary

There are many types of viruses that are created to cause problems for the others computers.

· Virus It is a piece of computer code, software or document written to harm the others computers and sent out by attackers. It can transfer to another computer through e-mails or file transfer. Viruses can hide by attacking itself to file on the computer. It starts its infection when the user accesses the affected file.

· Worm It is a malicious program that replicates and runs itself. It is different from viruses in that it does not need to attach itself to a program to infect computers. Worms do not damage data or applications only; they can harm the network due to consuming it bandwidth.

<span style="font-family: Georgia,serif; font-size: 120%;">· Trojan <span style="font-family: Georgia,serif; font-size: 120%;">It is a type of worms and it does not need to be attached to other software. It appears as useful software. Trojans can spread and make damages like viruses and sometimes can be more significant.

<span style="font-family: Georgia,serif; font-size: 120%;">There are also software that are installed on a computer without the user knowing. They can cause some damages inside the computers like changing the computer configuration.

<span style="font-family: Georgia,serif; font-size: 120%;">· Adware <span style="font-family: Georgia,serif; font-size: 120%;">It is a soft program that displays advertising on the computers. These advertisements can be in form of popup windows which are sometimes difficult to control.

<span style="font-family: Georgia,serif; font-size: 120%;">· Grayware (malware) <span style="font-family: Georgia,serif; font-size: 120%;">It is a file or program that is much harmful than a virus. Most of grayware attacks are phishing attacks such as persuading the user to fill out online form with some personal information. Then, the entered data is sent to the attackers.

<span style="font-family: Georgia,serif; font-size: 120%;">· Spyware <span style="font-family: Georgia,serif; font-size: 120%;">It is a type of grayware that is similar to adware. It distributes without knowing of the user. It can gather data and monitor activity on the computer. Then, it send the information to the spyware’s publisher.

<span style="font-family: 'Comic Sans MS',cursive; font-size: 12pt;">Resource

<span style="font-family: Georgia,serif; font-size: 120%;">CISCO Networking Academy Program Website