Examples of DOS Viruses
There are so many kinds of DOS viruses that I often feel that
mischievous minds have tried every imaginable trick. DOS viruses can
infect during bootup or warm booting, across a network, when running
programs, when copying files, when you scan files for computer
viruses, or when you list the files on your hard drive. They have
been known to use modems to dial long distance numbers when
unsuspecting users left their PCs on at night. They can display
elaborate graphics, sounds, and games. They can corrupt programs,
data, and hardware settings. Although most virus payloads wait for a
particular activation date or time, they can be computationally
random or key off some other event (such as hitting
Ctrl-Break
). Others lie in wait for the user to
unknowingly type in a particular keyword to set off some sort of
damage routine. Computer viruses can taunt people and display
questions the end user must answer in some twisted form of a quiz
show. If you answer incorrectly, they do more damage.
The Cascade
virus infects .COM
files and makes the letters you were typing fall to the bottom of the
screen. The
Jerusalem
virus infects
.COM
,
.EXE
,
.BIN
,
.PIF
, and
.OVL
files. It displays a “pong”
black box that floats around the screen and it will delete any
executables run on Friday the 13. The
Flip
virus horizontally flips the screen image
between four and five o’clock. The
Keypress
bug randomly interferes with keyboard typing so that a user thinks she is continually ...
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