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Naketa Cornegay

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Michael Shiroya

TROJANS, VIRUSES, AND WORMS

Trojans, Viruses, and Worms are all damaging to your computer system. If you do not know any basic knowledge on these three things, it can be harmful. If you do not know how to protect your computer these things can be harmful also. So to give you some more information, we will be talking about Trojans, viruses, and worms in our paper.

Trojan Horses are files that claim to be harmless but, in fact, are nasty. You may think it is safe, but hidden inside is usually something harmful, probably a worm or a virus. The bait of Trojans is that you may download a file or an email attachment, believing that it is harmless, but once you run the file, the worm or virus then infects your computer. An important distinction between Trojan horse programs and true viruses is that they do not replicate themselves. An example of a Trojan is the PWSteal.Trojan.

����������� Worms, unlike Trojans, are programs that duplicate themselves from system to system without the use of a host file. An important difference between worms and viruses is that viruses require the spreading of an infected host file. Furthermore, worms and viruses use the host file differently. A worm will release a file that already has the �worm� macro within the document. The entire file will them travel in the network from computer to computer. Bearing this in mind, the file itself should therefore be considered the worm. Worms generally come through email attachments; however computers can also get infected if they accept a Trojan file which has a worm as the payload.� If one was to receive a worm program via email, and run it, the program will send the worm file to everyone on the person�s address book. The person who receives the file will fall into the same situation and so the cycle of infection and multiplication continues.

����������� A virus is a program that alters the way a computer operates, without the consent or knowledge of the user. Viruses are spread through executable files we get from. Viruses are often disguised under Trojans, which are carriers of the virus. For a program to be classified as a virus it must execute itself, replicate itself, and often place their own code in the path of execution of another program. For example, it may replace other executable files with a copy of the virus infected file, damage the computer by damaging programs, deleting files, or reformat the hard disk. Some viruses are not programmed to do any damage, but simply to replicate themselves and show their presence by presenting text, video, and audio messages; and in the process they take up memory that would have otherwise been used by legitimate programs. Consequently, they often result in erratic behavior and in system crashes. Moreover, many viruses are bug-ridden, and these bugs may also cause system crashes and loss of valuable data.

����������� There are five types of viruses: file infector, boot sector, master boot record, multi-partite, and macro viruses. File infector viruses infect program files. They infect executable code, for instance .com and .exe files. They can infect other files when an infected program is run from a floppy disk, hard drive, or from a network. These viruses reside in memory so that once the memory is infected; all other non infected executable files that run become infected. Examples of file infector viruses include Jerusalem and Cascade.

����������� Boot sector viruses infect the boot record on floppy disks and hard disks. Boot sector viruses attach themselves to the system area of a disk and activate when the user attempts to open from the infected disk; usually all that is required to become infected is to attempt to start up your computer with an infected floppy disk. Like file infector viruses, boot sector viruses are also memory resident that is, the virus remains in memory. Therefore all files that are not writing protected will become infected once the floppy disk is accessed. Examples of boot sector viruses include Michelangelo and Stoned.

����������� Master boot record viruses are also memory resident viruses and infect disks in the same way as boot sector viruses. The distinction between these two virus types lies in is location of the viral code. Master boot record infectors save copy of the master boot record in a different location. Windows NT computers that become infected by either boot sector viruses or master boot sector viruses will not boot. This is due to the difference in how the operating system accesses its boot information, as compared to Windows 95/98. If your Windows NT system is formatted with FAT partitions you can usually remove the virus by booting to DOS and using antivirus software. If the boot partition is NTFS, the system must be recovered by using the three Windows NT Setup disks. Examples of master boot record infectors include AntiExe, and Unashamed.

����������� Multi-partite viruses are also known as poly-partite viruses and they infect both boot records and program files. They are difficult to repair. If the boot area is cleaned, but the files are not cleaned, the boot area will be re-infected with the virus. This will also be the case for cleaning infected files. If the virus is not removed from the boot area, any files were cleaned will be re-infected. Examples of poly-partite viruses include Anthrax and Tequilla.

����������� Macro viruses infect data files. They are the most common of all the virus types. Macro virus can be programmed such that they not only infect data files, but can also possibly infect other files as well. All of these viruses use another program�s internal programming language, created to allow users to mechanize certain tasks within that program. These viruses can be created relatively easily and hence they are many of them circulation around today. Examples of macro viruses include W97M.Melissa and W97M. Groov.

����������� There are many ways to protect your computer. Some ways are as follows: Do not accept files from anyone you do not know; do not run or even peek at files you receive through email from people you don�t know. Purchase a good, recent anti-virus software program. Encourage your acquaintances, business associates and other people you regularly exchange emails with to send messages as rich "text format" files instead of Word documents. In this way the document�s appearance will be preserved without concealing malicious code. Be wary of friends who pass along funny video clips via e-mail; neither of you know the origin of this software and whether it is bug free. Be careful about disks from other computers. Since not everybody uses anti-virus software programs, before using a disk, one should run a virus scan on it. Set up a regular time to update the virus scans and follow up on those times. You should backup important files regularly. Avoid pornography sites, game sites, and web sites that offer free screen savers or share-ware, they are often key breeding grounds of Trojan horses.

����������� In conclusion, viruses, Trojans, and worms can be damaging to your computer. If you follow safe and precise steps you can prevent your computer from getting infected. Also just having basic knowledge of these things could help out also.