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Computer Virus
Overview
What
is a Virus?
A virus is a small computer program that copies
itself by attaching to another computer program. The virus
may carry out some task, which is often damaging. Even if
a virus is intended to be harmless, it can be detrimental
nonetheless; viruses occupy memory and disk space which can
be enough to disrupt normal operation of your computer.
A
virus may contain a "time-bomb," where an activity is designed
to occur on a certain date or when a condition has been fulfilled.
An odd message may flash on the screen, or important files
may be corrupted
.How Are Viruses Spread?
Some viruses infect
a microcomputer and then infect every diskette that is inserted,
unless the diskette is write-protected.
Other viruses attach
themselves to programs, and after the infected program
is run, subsequent programs are infected as well.
Infected
diskettes passed around by computer users in an office can
cause viruses to spread. Viruses have become more of a problem
in recent years, primarily because more people are sharing
software in the public domain or on bulletin boards; these
distribution media make it very easy for undetected viruses
to spread quickly.
Symptoms of a Virus
Not all viruses
are harmful; certain viruses only replicate and have no other
intended function. The damage viruses cause range from minor
to severe. Some viruses announce their presence very clearly
by flashing unusual messages or graphical displays. However,
usually the presence of a virus can be very subtle or completely
undetectable up to a point.
You may suspect a virus
when:
- You notice changes in file sizes or contents
- There is unaccounted use of RAM or your system is getting
bigger without your having made changes
- Unusual error messages appear
- The disk lights stay on longer than they used to
- Applications take a long time to load, unexpectedly quit,
or crash
- Files or folders seem to be missing
Although it's important to be aware
of the potential presence of viruses, rest assured that unusual
behavior is most often due to bugs in software or conflicts
between drivers, TSRs and other software. In fact, 99 % of
all suspected new viruses are eventually proven to be (merely)
mundane bugs in the operating system or applications being
used.
Identifying
and Combating Viruses
Anti-Viral Software
The most
important thing you can do to safeguard against viruses
or combat existing ones is to use anti-viral software. There
are three functions performed by anti-viral software: prevention,
detection, and removal. Certain software programs prevent
viruses from infecting your computer by noting viral-like
activity; other programs examine disks or files for viral
code (usually on demand) and can identify and remove existing
viruses.
There are many anti-viral programs,
both public domain and commercial, available for the PC.
Assumption
College utilizes McAfee and Eliashim software for IBM compatible
machines and SAM Anti-Virus and Virex for Macintosh
computers across the campus.
These can be obtained and installed
through Information Technology. On PC's the system is
set up to scan all files on startup. On Macintosh machines
all inserted disks are automatically scanned.
Procedure if a virus is detected
In
case a scan repeals the existence of a virus on
your computer, immediately notify Information Technology
at extension 7060. Do not use your computer until Information
Technology removes the virus. This will help to
ensure that data is not lost and that the College can track
the incidence of virus occurrences on campus
.Prepared
by Dr. Robert Fry
22 June 1997
Assumption College with excerpts from the Expert Partners Program
Expert.Partners@forsythe.stanford.edu
ITSS Customer Assistance, Stanford University
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