There are a lot of doomsday warnings throughout the PC world about the potential destruction that computer viruses can cause. It is also true that there are a lot of myths and exaggerations circulating. With an increasing number of shops adding PC-based CNCs and networking capabilities, the question is raised, "How immune from computer viruses are CNCs?" Is there a need to take protective action against CNCs being infected?
What is a computer virus? Symantec's AntiVirus Research Center defines a computer virus as a piece of software designed and written to adversely affect your computer by altering the way it works without your knowledge or permission. This piece of software, or code, implants itself in one of your executable files and spreads systematically from one file to another. Computer viruses do not spontaneously generate—they must be written. Usually a virus has two distinct functions:
- Spread itself from one file to another without your input or knowledge. A virus can often lurk in memory waiting to infect the next program that is run or the next disk that is accessed. This is known as self-replication or propagation.
- Implements the symptom or damage planned by the perpetrator. This is known as the viruses' payload.
The viruses' payload can be benign or malignant. A benign virus is one that is designed to do no real damage to your computer. For example, a virus that conceals itself until some predetermined date or time and then does nothing more than display some type of a message or picture is considered benign.
A malignant virus is one that inflicts malicious damage to your computer. A malignant virus may alter one or more of your programs so that they do not work correctly, or it may alter the directory information in one of your system areas so that you cannot mount a disk partition or find and launch one or more programs. Some of the more malignant viruses will erase a hard disk or delete files.
How do viruses get transmitted? There is much debate throughout the computer industry about how most viruses are transmitted. There are many who believe that the majority of infections come through shareware over the Internet. There are an equal number who say "not so" because most shareware organizations do such a good job of policing themselves against viruses. They point the finger at retail companies who accidentally distribute viruses to their customers, some from the original supplier and others because of the common policy of re-shrink wrapping returned software and putting it on the shelf again. Regardless of where you get the software or how it is transmitted—Internet download, diskette, or CD—be alert to the fact it could contain a virus.
How many viruses are there? Experts estimate there are over 15,000 viruses that exist today. Fortunately there are only about 260 that are "in the wild" (in general circulation), and the rest live only in research labs. It is estimated that there are an additional six to nine new viruses appearing daily. That is not as bad as it sounds since there are roughly an equal number of old viruses dropping out of circulation.
Which CNCs are vulnerable? If you have a CNC that is based on proprietary architecture and not capable of running third-party computer software, then rest easy, because you are immune to a virus infection—a plus for proprietary controls. Also, if you have a PC-based control but no provision to run third-party software, then you are also safe from viruses since there are no known viruses that are transmitted by part programs. But if you are among the increasing number of users who are moving to open architecture controls with capability to run third-party software, then virus protection should be a high priority just as it is with any PC user.
It is clear that all PC users are at risk of contracting a computer virus and need virus protection. It is also clear that PC-based CNCs running third-party software are encountering the same risk and need the same virus protection. There are a number of antivirus software packages (virus killers) available that do a good job of finding and eradicating most viruses. One of the key elements in selecting an antivirus package is how often the vendor updates the product's virus library of signatures. This is the code that helps identify the virus. With new viruses being distributed every day, it is important for the antivirus software to be kept current. PC World magazine (March 1998) published a list of eight antivirus software packages and their evaluations. If you are a user of PC-based CNCs and plan to run third-party software, it would be well worth adding virus protection to your control.