🚀 go-pugleaf

vanaards@project4.computer-science.manchester.ac.uk (Steven van Aardt)
writes:
>
>   Is it possible to write a PC virus which installs itself whenever
> you place an infected disk in the drive and do a DIR command ?

Yes. But on a PC this requires certain conditions, which mean it
probably wouldn't spread very far.

Mark Aitchison, Physics, University of Canterbury, New Zealand.

I would like to know just what these conditions are.  If you have an
clean, uninfected system with the normal system files, COMMAND.COM,
etc., I would think that it is impossible to infect system memory or
another disk by doing a directory listing on an infected diskette.
(Of course, if you don't have a clean system with unmodified system
files, anything can happen.)  At no time does COMMAND.COM transfer
program control to any executable code on a diskette when it does a
directory listing via the DIR command.  It looks at the diskette's
root directory, files, and all other areas of the diskette as pure
data.  There is no way for a virus to become activated and infect a
system if control is not passed to it at some point.  With regard to
the comment about the Stoned virus behaving this way, Stoned will
infect a diskette if you do a DIR on it from a system which has the
virus active in memory (as will most other memory-resident viruses).
The only way for it to become active is by booting a system from an
infected floppy or hard disk - it cannot become active if you do a DIR
on an infected diskette from a clean system.  And I would venture to
say that this holds true for viruses in general.