A Look Into The Computer Virus Essay, Research Paper

A Look Into The Computer Virus

by, Michael Ross

Engineering 201.02

January 22, 1997

Most of us swap disks with friends and browse the Net looking for downloads.

Rarely do we ever consider that we are also exchanging files with anyone and

everyone who has ever handled them in the past. If that sounds like a warning

about social diseases, it might as well be.

Computer viruses are every bit as insidious and destructive, and come in a vast

variety of strains. A computer virus tears up your hard drive and brings down

your network. However, computer viruses are almost always curable diagnosed,

and cures for new strains are usually just a matter of days, not months or years,

away.

Virus, a program that “infects” computer files (usually other executable

programs) by inserting in those files’ copies of itself. This is usually done in

such a manner that the copies will be executed when the file is loaded into

memory, allowing them to infect still other files, and so on. Viruses often have

damaging side effects, sometimes intentionally, sometimes not. (Microsoft

Encarta 1996)

Most viruses are created out of curiosity. Viruses have always been viewed as a

well written, creative product of software engineering. I admit there are many

out there who create them out of malice, but far more people are just meeting a

challenge in software design. The people who make anti-virus software have much

more to benefit from the creation of new virii. This is not a slam, just an

observation. A common type of virus would be a Trojan Horse, or a destructive

program disguised as a game, a utility, or an application. When run, a Trojan

Horse does something devious to the computer system while appearing to do

something useful (Microsoft Encarta, 1996). A Worm is also a popular type of

virus. A worm is a program that spreads itself across computers, usually by

spawning copies of itself in each computer’s memory. A worm might duplicate

itself in one computer so often that it causes the computer to crash. Sometimes

written in separate “segments,” a worm is introduced secretly into a host system

either for “fun” or with intent to damage or destroy information. The term ?

Worm’ comes from a science-fiction (Microsoft Encarta 1996).

Some viruses destroy programs on computers although, the better virii do not.

Most virus authors incorporate code that specifically destroys data after the

virus determines certain criteria have been met, that is, a date, or a certain

number of replications. Many virus do not do a good job of infecting other

programs and end up corrupting, or making the program they are trying to infect

completely unusable. The purpose of a virus, in many cases, is to infect as many

files, with little or no noticeable difference to the user.

How does a virus scanner work?

Most virus scanners use a very simple method of searching for a particular

sequence of bytes that make every virus unique, like a DNA sequence. When a new

virus is discovered, a fairly long sequence of bytes from it is inserted into

the anti-virus software database. That’s why you need to keep them updated. Any

virus scanner you buy should handle at least three tasks: virus detection,

prevention, and removal. There are some virus scanners that use a method called

heuristic scanning. They use ‘rules of thumb’ that can be used to identify some

virii that has not even been put in the virus database yet. What are the rules

of thumb? Well, they are basic assembly language clues that make the file

suspicious, such as a JMP instruction at the top of the file. No virus scanner

is infallible and anyone that tells you so have no idea what they are talking

about. The two best virus scanners in my opinion are F-PROT and THUNDERBYTE.

They use the heuristic method described above.

In conclusion; viruses are, and always will be, a part of the computing world.

They have been around since programming began and will continue to thrive as

long as computers are used. Technology will force us to adapt and be aware that

any information we place on a computer may not be safe.

References

Deadly New Computer Viruses Want To Kill Your PC usability.

By James Daley http://www.headlines.yahoo.com/news/stories

originally published in Computer Shopper December 1996

Microsoft Encarta 96; Reference Material Microsoft corporation