what is computer virus and the types of computer virus?

Question

prevention of such computer viruses. Advantages and Disadvantages of computer virus

Answer 1

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Answer 2

The Common Types of Computer Viruses

Computer viruses are similar to biological viruses in the way they multiply in number and in the way they need a host to survive. However, in both scenarios there must be a cause, such a weak immune system or an expired anti-virus program, in order for the virus to penetrate and spread. Having a reliable anti-virus program is the best solution.



Just as a biological virus spreads by injecting its DNA into a host cell, whereas a computer virus needs to attach itself to a document or program to infect other computers and programs.



The way a computer virus infiltrates your PC depends on the type of virus it is. Because all computers viruses have their own features and factors that make them unique and dangerous to the health of your computer. Making it important than ever to learn about the different types of computer viruses lurking in the corners of cyberspace and on the fringes of your hard drive. The advantage of learning more about these computer viruses is two fold. First, you'll gain valuable knowledge, and second you'll be able to better prevent and deal with a computer virus when and if it preys your computer.



Due to the many different types of computer viruses, it can be confusing at times to diagnose what kind of virus your computer is suffering from. To make the identifying process easier, we've listed the three basic types of viruses that you will likely encounter.



These computer viruses include:







Trojan Horses

Worms

Email Viruses





The Trojan virus gets its name from an incident that occurs in Homer's Iliad. Similar to how the Greeks in Homer's poem sent an army of men, hidden in a wooden horse, to the Trojans to get into the wall of the city. A Trojan horse appears to be nothing more than an interesting computer program or file, such as "saxophone.wav file" on the computer of user who's interested in collecting sound samples. The Trojan virus once on your computer, doesn't reproduce, but instead makes your computer susceptible to malicious intruders by allowing them to access and read your files. Making this type of virus extremely dangerous to your computer's security and your personal privacy. Therefore, you should avoid downloading programs or files from sites if you're not 100 percent positive of what the file or program does.



A Worm is a virus program that copies and multiplies itself by using computer networks and security flaws. Worms are more complex than Trojan viruses, and usually attack multi-user systems such as Unix environments and can spread over corporate networks via the circulation of emails. Once multiplied, the copied worms scan the network for further loopholes and flaws in the network. A classic example of a worm is the ILOVEYOU virus.



The best way you can protect yourself from worms is by updating your security patches. Operating systems and application vendors normally provide these patches. In addition, you should avoid opening email attachments from unknown senders.



Email viruses use email messages to spread. An email virus can automatically forward itself to thousands of people, depending on whose email address it attacks. To avoid receiving virus-laden emails, always check that your antivirus software is up-to-date and also stay clear of opening attachments, even from friends that you weren't expecting or don't know anything about. Also, block unwanted email viruses by installing a spam filter and spam blocker.





Hope this helps!!

Answer 3

Computer Virus is a kind of malicious software written intentionally to enter a computer without the user’s permission or knowledge, with an ability to replicate itself, thus continuing to spread. Some viruses do little but replicate others can cause severe harm or adversely effect program and performance of the system. A virus should never be assumed harmless and left on a system. Most common types of viruses are mentioned below:





Resident Viruses

This type of virus is a permanent which dwells in the RAM memory. From there it can overcome and interrupt all of the operations executed by the system: corrupting files and programs that are opened, closed, copied, renamed etc.



Examples include: Randex, CMJ, Meve, and MrKlunky.



Direct Action Viruses

The main purpose of this virus is to replicate and take action when it is executed. When a specific condition is met, the virus will go into action and infect files in the directory or folder that it is in and in directories that are specified in the AUTOEXEC.BAT file PATH. This batch file is always located in the root directory of the hard disk and carries out certain operations when the computer is booted.



Overwrite Viruses

Virus of this kind is characterized by the fact that it deletes the information contained in the files that it infects, rendering them partially or totally useless once they have been infected.



The only way to clean a file infected by an overwrite virus is to delete the file completely, thus losing the original content.



Examples of this virus include: Way, Trj.Reboot, Trivial.88.D.



Boot Virus

This type of virus affects the boot sector of a floppy or hard disk. This is a crucial part of a disk, in which information on the disk itself is stored together with a program that makes it possible to boot (start) the computer from the disk.



The best way of avoiding boot viruses is to ensure that floppy disks are write-protected and never start your computer with an unknown floppy disk in the disk drive.



Examples of boot viruses include: Polyboot.B, AntiEXE.



Macro Virus

Macro viruses infect files that are created using certain applications or programs that contain macros. These mini-programs make it possible to automate series of operations so that they are performed as a single action, thereby saving the user from having to carry them out one by one.



Examples of macro viruses: Relax, Melissa.A, Bablas, O97M/Y2K.



Directory Virus

Directory viruses change the paths that indicate the location of a file. By executing a program (file with the extension .EXE or .COM) which has been infected by a virus, you are unknowingly running the virus program, while the original file and program have been previously moved by the virus.



Once infected it becomes impossible to locate the original files.



Polymorphic Virus

Polymorphic viruses encrypt or encode themselves in a different way (using different algorithms and encryption keys) every time they infect a system.



This makes it impossible for anti-viruses to find them using string or signature searches (because they are different in each encryption) and also enables them to create a large number of copies of themselves.



Examples include: Elkern, Marburg, Satan Bug, and Tuareg.



File Infectors

This type of virus infects programs or executable files (files with an .EXE or .COM extension). When one of these programs is run, directly or indirectly, the virus is activated, producing the damaging effects it is programmed to carry out. The majority of existing viruses belong to this category, and can be classified depending on the actions that they carry out.



Companion Viruses

Companion viruses can be considered file infector viruses like resident or direct action types. They are known as companion viruses because once they get into the system they "accompany" the other files that already exist. In other words, in order to carry out their infection routines, companion viruses can wait in memory until a program is run (resident viruses) or act immediately by making copies of themselves (direct action viruses).



Some examples include: Stator, Asimov.1539, and Terrax.1069



FAT Virus

The file allocation table or FAT is the part of a disk used to connect information and is a vital part of the normal functioning of the computer.

This type of virus attack can be especially dangerous, by preventing access to certain sections of the disk where important files are stored. Damage caused can result in information losses from individual files or even entire directories.



Worms

A worm is a program very similar to a virus; it has the ability to self-replicate, and can lead to negative effects on your system and most importantly they are detected and eliminated by antiviruses.



Examples of worms include: PSWBugbear.B, Lovgate.F, Trile.C, Sobig.D, Mapson.



Trojans or Trojan Horses

Another unsavory breed of malicious code are Trojans or Trojan horses, which unlike viruse

Answer 4

Here are a list of free tutorials related to viruses, spyware, etc. Fell free to visit:



http://www.gocomputertraining.com/computer-security.html

Answer 5

Was this a challenge to see how many time you could use the word "which" in a sentence without sounding like an idot? If so, you fail.