User Guide

User’s Guide xiii
Preface
What happened?
Ifyou’veeverlostimportantfilesstoredonyourhard disk,watchedindismay
as your computer ground to a halt only to display a prankster’s juvenile
greeting on your monitor, or found yourself having to apologize for abusive
e-mail messages you never sent, you know first-hand how computer viruses
and other harmful programs candisrupt yourproductivity. Ifyou haven’tyet
suffered from a virus “infection,” count yourself lucky. But with more than
50,000 known viruses in circulation capable of attacking Windows- and
DOS-based computer systems, it really is only a matter of time before you do.
The good news is that of those thousands of circulating viruses, only a small
proportion have the means to do real damage to your data. In fact, the term
“computer virus” identifies a broad array of programs that have only one
feature in common: they “reproduce” themselves automatically by attaching
themselves tohostsoftwareordisksectorsonyourcomputer,usually without
your knowledge. Most virusescause relatively trivial problems, ranging from
the merely annoying to the downright insignificant. Often, the primary
consequenceofavirus infectionis the cost you incur intimeandefforttotrack
down the source of the infection and eradicate all of its traces.
Why worry?
So why worry about virus infections, if most attacks do little harm? The
problem is twofold. First, although relatively few viruses have destructive
effects,thatfactsaysnothingabouthowwidespreadthemaliciousvirusesare.
In many cases, viruses with the most debilitating effects are the hardest to
detect—the virus writer bent on causing harm will take extra steps to avoid
discovery. Second, even “benign” viruses can interfere with the normal
operationofyourcomputerandcancauseunpredictablebehaviorinother
software. Some viruses contain bugs, poorly written code, or other problems
severe enough to cause crashes when they run. Other times, legitimate
software has problems running when a virus has, intentionally or otherwise,
altered system parameters or other aspects of the computing environment.
Trackingdownthesourceofresultingsystemfreezesorcrashescandraintime
and money from more productive activities.
Beyond these problems lies a problem of perception: once infected, your
computer can serve as a source of infection for other computers. If you
regularly exchange data with colleagues or customers, you could unwittingly
passonavirusthatcoulddomoredamagetoyourreputationoryourdealings
with others than it does to your computer.