Anonymous asked this question on 4/23/2000:

I am doing a paper on computer viurs#. I need some information on differant virus# and how one can protect themselves from these virus#. I am a student in college. I would greatly appreciate any help. Thank you.

NataliePratt gave this response on 4/24/2000:

A virus is a parasitic program written to intentionally enter a computer without the user's permission or knowledge. It spreads from one computer to another by attaching itself to other programs. Some viruses will damage or destroy files, or even delete all of your data. Although some viruses do little but replicate, others can cause serious damage or effect program and system performance. A virus should never be assumed harmless and left on a system. Once the virus is made it will generally be distributed through shareware, pirated software, e-mail, or floppies. Once the virus infects someone's computer, it will either start infecting, destroying, or over writing data, and eventually it could corrupt the software.

90% of viruses are contracted from floppy's. The floppy brings information from one source and puts the infected file onto your computer. A virus will infect a disk and when that disk is put into your computer your computer will then become infected. Booting from an infected diskette transfers most viruses. Remove disks from your A drive as soon as you are through with the disk.

Another safety precaution is to practice safe downloading. If you are downloading software from a bulletin board or other computer network including the Internet, always download to a floppy disk. You should then scan the disk for possible virus infections. The best way to protect your computer from viruses is to use anti-virus software, which can determine if a virus is resident on your computer. Regular scanning of your computer files is the best prevention to keep your system free of viruses. Many anti-virus software programs allow files to be automatically scanned for viruses when downloading files from the web.

Be sure to check all new software for viruses. Even shrink-wrapped software from a major publisher can contain a virus. There have been instances where commercial software has been sold with a virus. Don't use illegal software. If the software has been obtained illegally, how can you be sure that it doesn't contain a virus? Use extreme caution when using public domain and shareware software or any new software.

Email is another big area in which to take precautions. Have your anti virus software set to automatically scan your incoming email. And, treat attachments as high risk. Most viruses that are transported via email are in the attachment.

Signs that your computer may be infected with a virus include:

Files are suddenly deleted Changes to the volume label name Clusters are marked as bad in the FAT Sectors on the hard disk appear to be randomly overwritten Replaces the MBR (Master Boot Record) with own code Creates more than one partitions Attempts to access the hard disk drive can result in error messages such as invalid drive specification. Causes cross-linked files Causes a "sector not found" error Causes the system to run slow Attempts to access the disks when there should not be any read or write activity Logical partitions are created or partitions decrease in size A directory may be displayed as garbage Directory order may be modified so files such as COM files will start at the beginning of the directory Hardware problems such as keyboard keys not working, printer issues, modem issues etc. Disables ports such as LPT or COM ports Causes keyboard keys to be remapped Recent creation dates on old program files Unusual displays on the computer screen Alterations to the system time and date The system hangs or freezes randomly Random activity on HDD or FDD Increases in file size Decreases in the main memory or reduction of disk space Random changes to file or memory size Extended boot times Increase disk access times Your computer is making strange noises, music, clicking sounds or beeps Displays strange pictures Different types error messages or strange messages appear in files or on programs

Some General Rules to follow include: - Always write-protect your systems and program disks. Write-protect tabs are easy to use and very effective. You should write only on data disks. - Only copy files from the original distribution disks. - Do not loan out program disks. They may be infected when they are returned. If you do loan a disk, check it for viruses before using the disk on your computer system. - Make sure all the .COM and .EXE system and program files are set to read only. However, some viruses can now bypass this method. - Always be on the lookout for strange occurrences - In a computer lab, do not allow users to run their own programs or boot the computer system with their own disks. All program disks and hard disks in a lab should be checked frequently for viruses. If users are allowed to use their own program disks, they must be scanned before they are used in a lab setting.

Viruses are divided into several catagories. They most common are: Boot Sector Virus Macro Virus Worm Virus Resident Virus Stealth Virus

Each type of virus attacks the system in a different manner. As far as numbers go some anti virus software checks for 40,000 different viruses during a typical scan. However, as soon as one virus is wiped out a new one is developed.

Good Luck and I hope this helps. Natalie Pratt Midwest Investigative Consultants