E11) Can I contract a virus on my PC by performing a "DIR" of an
     infected floppy disk?

If you assume that the PC you are using is virus free before you
perform the DIR command, then the answer is no.  However, when you
perform a DIR, the contents of the boot sector of the diskette are
loaded into a buffer for use when determining disk layout etc., and
certain anti-virus products will scan these buffers.  If a boot sector
virus has infected your diskette, the virus code will be contained in
the buffer, which may cause some anti-virus packages to give the
message "xyz virus found in memory, shut down computer immediately".
In fact, the virus is not a threat at this point since control of the
CPU is never passed to the virus code residing in the buffer.  But,
even though the virus is really not a threat at this point, this
message should not be ignored.  If you get a message like this, and
then reboot from a clean DOS diskette and scan your hard-drive and
find no virus, then you know that the false positive was caused by the
fact that the infected boot-sector was loaded into a buffer, and the
diskette should be appropriately disinfected before use.  The use of
DIR will not infect a clean system, even if the diskette it is being
performed on does contain a virus.


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