"And it is just as easy to have programs written
on a CD which automatically run when the CD is
accessed. This is how viruses get away with their
mischeif. While AV software may be able to wipe a
virus on a floppy, a) on a CD there is plenty of
room for multiple copies to watch over each other,
and b) a CD cannot be overwritten that easily."
Point B is invalid because of your earlier
statement:
"If write attempts are made to specific hidden
read only files, the virus or worm built into the
software will corrupt enough data to foil the
tampering attempt, making the software unusable."
Since CD's "cannot be overwritten that easily"
destroying the data contained on the CD wouldn't
be an option. If you used a small writable sector
or room on the users HD to store a "no copy" file
(a method commonly used) it could be just as
easily changed and wouldn't offer much protection.
Creating systems of copyright protection in both
hardware and software on user systems can stop the
initial "casual" copying of files, but cracked
versions are released in next to no time. So the
only option your virus would have is to destroy
data on the users computer (an option that was
explored on some software in the late 80's). But
even then the boot sector of the CD need not be
run, so none of the viruses would be initialised
in the first place.
Bryan Moss