¶ … computer virus is among the greatest enemy of computer technology's globalization. In just a few split of seconds, it can turn our endeavor of automating our diverse activities into a nightmare. This is especially a catastrophe to businesses whose operation at a large percentage depends on computerized data access and retrieval. Globally, computerization is the trend among businesses. Thus, the damage that computer viruses can cause is a global threat and problem to the stabilization and progress of businesses and economy. There are many types of computer virus. Almost everyday, a new computer virus is created. Since the emergence of computer networks, such as LAN, WAN, and the Internet, there has been quite a number instance where a computer virus had infected and brought damage to a great amount of information and data globally. As a consequence, many businesses are paralyzed when a computer virus attacks.

Purpose

This paper aims to provide useful information about computer viruses. By exploring the different types of a computer virus, the different existing viruses classified in each type, and the damage each virus can do to system data and files, this paper aims to provide the necessary and possible prevention tools and techniques to avoid the risks a computer virus can bring. It aims to provide a well researched and well presented report that draws clear conclusions and offers solid recommendations about the ways to handle virus threat.

1.2 Sources

The sources that will be used in this research paper will come from online literatures, journals, and recent researches and studies. These sources, especially the use of the Internet, are ideally beneficial for this research paper because of the wide-range of information that they generally provide.

This research paper will gather essential information pertaining to computer viruses and integrate them into a useful reading material and reference.

1.3 Authorization

For future recommendation of anti-virus softwares, it is essential that the user will obtain a licensed and authorized copy of the software. Basically, in this research study, the only subject that needs authorization is the use of legal copies of software.

2. Conclusion

Computer viruses are threats to computer systems and data. The usual purpose why viruses are being created is to maliciously damage computer systems and data. Those that are in greater risk of being attacked by a computer virus are computer systems that are connected to a network. This includes the LAN, WAN, and the Internet connections. To prevent from being infected by a computer virus, it is a critical standard operating procedure to implement anti-virus softwares. It is essential to provide computer systems with effective security tools that block viruses from infecting computers. Moreover, having the knowledge on the different viruses that exist and the corresponding ways to handle them is important.

3. Recommendation

Pertaining to the computer systems that are connected to a network, may it be a LAN, WAN, or the Internet, this research recommends that any computer connected to a network be equipped with anti-virus software and network security systems. In the growing demand of being connected to a network, these simple preventions are important to prevent the risk of becoming victims of holes in technology. On the other hand, pertaining to future researches that will be conducted on computer viruses, it is recommended that a list of further viruses as well as the necessary techniques to prevent or solve the problems they may cause be provided to the readers. This is important since almost everyday new computer viruses emerge.

4. Threats to Local Area Networks (LAN)

There are different types of threats to local area networks. Some of which are threats on the existence of computer data itself while some are threats on the security of computer systems across a network. An example of data threats are computer viruses, worms, and Trojan horses, while an example of threats on computer systems' security are the crackers. Following is a discussion of these types of threats to local area networks.

Computer Viruses

What is a computer virus? Mark K. Brouwer, in his Virus or Hoax? online, defines a computer virus as program which reproduces its own code by attaching itself to other programs in such a way that the virus code is executed when the infected program is executed.

A they have an infection phase where they reproduce widely, and an attack phase where they do whatever damage they are programmed to do.

Boot Sector

Before discussing what a boot sector virus is, it is important to have an overview...

A boot sector functions as a library of the corresponding locations of each data. In a floppy disk or hard drive, data are basically spread on segments at different locations. To access data would require a disk to first locate for the boot sector so that it will know the exact location of the data being accessed.
Now, what a boot sector virus does is to damage and destroy the information in the library of locations of data - the boot sector. When this virus infects a boot sector, it puts the boot sector at a loss, making it incapable of identifying the exact location of data. Consequently, this can also impair an entire operation. A few examples of a boot sector virus are Michaelangelo, the Form, and Junkie Virus (Mehta, 2001).

File-Infecting

The main action that a file-infecting virus does is to modify and damage files. This kind of virus, which is a common type of computer virus, usually attacks executable files such as.EXE and.COM files. By attaching codes to a file, or by modifying the original code of a file, it is possible that a file can no longer be executable.

Other file-infecting virus attaches itself on executable files. When the infected executable is run, the virus triggers itself to attach on other executable files. Examples of file-infecting virus are Nemesis, Friday the 13th, and Enigma (Mehta, 2001).

As its name implies, email viruses are those that infect emails. However, they do not actually infect the message in the email itself. Such type of virus are embedded on files attached to an email. By downloading and opening a file that is infected with a virus, the virus will be triggered. One example of an email virus that has caused a lot of computer problems around the world is the I LOVE YOU virus. It is a WIN-32-based e-mail attachment written in VB script that disguised in the form of a love letter (Schmugar, 2000).

Macro macro virus is a type of virus, written in macro, which embeds itself to document files. This virus infects documents that were created in applications that support macro languages. It can also infect the applications supporting macro. This includes Microsoft Word, Excel, etc. Webopedia indicates that 75% of today's computer viruses are macro viruses (Webopedia, 2004).

4.1.5 Multipartite

Multipartite virus, or multi-part, has the capability of infecting computer systems in many ways. It can either infect the boot sector or the files in a computer. An online source has the following perfect definition of a multipartite virus.

Some viruses can be all things to all machines. Depending on what needs to be infected, they can infect system sectors or they can infect files. These rather universal viruses are termed multipartite (multi-part). Sometimes the multipartite virus drops a system sector infector; other times a system sector infector might also infect files. Multipartite viruses are particularly nasty because of the number of ways they can spread. Fortunately, a good one is hard to write. What is a multipartite virus? A multipartite virus will infect both the boot sector and program files. One common multipartite virus is the Tequila virus

Script script virus is developed under script programming. Similar to other types of virus, a script virus is triggered when an infected file executes.

Signatures signature virus can be identified by a string of bits or binary patterns (Webopedia.com). There are three ways where such patterns are created: encrypted code, mutating code, and polymorphic code.

Worms computer worm virus is a type of virus that is independent. Unlike the computer virus in which its spread is dependent on the access of files and boot sectors, the computer worm does not depend on anything and can travel across a network to spread the damages it is programmed to perform. One example of a worm virus is the Internet worm of 1988 that infected all SUN and VAX systems. To prevent from being infected, many sites were disconnected from the Internet.

Trojan Horses

Trojan horse is not virus. However, it is capable of destroying pertinent information and data in a hard disk. Unlike a virus that spreads to files and boot sector, a Trojan horse is simple a program that performs malicious actions. Usually, a Trojan horse program hides itself in the form of valid applications and programs. When such program is executed, the Trojan horse performs its objective of destroying data in your computer. Some examples of Trojan horses are Darth Vader, the Aids Information, and Twelve Tricks A and B (Mehta, 2001).

Hackers and Crackers

Aside from the computer viruses, worms, and Trojan horses that has the capability of destroying important data and…