Once again, when I used the phrase, "textual file," it was intended to
be taken figuratively as a contrast to a graphic file and not literally.
I was not focusing in on file formats, executable files vesus
non-executable files, ASCII files versus binary files, or executable
files and macros as versus carriers in opposition to plain old data
files. My main point was merely that viruses on a system can impact on
the hard drive whatever their source and that this can be an issue for
archives kept on those hard drives even if the files which are contained
cannot carry or transmit the virus or be effected themselves.
filmscanners_owner@halftone.co.uk <> wrote:
>> -----Original Message-----
>> From: filmscanners_owner@halftone.co.uk
>> [mailto:filmscanners_owner@halftone.co.uk] On Behalf Of LAURIE
>> SOLOMON Sent: Saturday, March 29, 2003 9:01 AM
>> To: frankparis@comcast.net
>> Subject: [filmscanners] RE: keeping the 16bit scans
>>
>>
>> Frank,
>> I agree with your point two, although I suspect that Robert
>> would not. However, regarding your first point, you are
>> wrong. Viruses can be an issue whenever you are dealing with
>> media connected to an operating system - particularly if that
>> system is connected to the internet. There are all kinds of
>> viruses and worms which can attack the sectors of hard drives
>> which contain all the information about what folders and
>> files are loccated where on the physical hard drive so that
>> they can be located and retrieved by the system when they are
>> called for. Viruses are not merely restricted to effecting
>> textual materials and files.
>
> I guess I was restricting my thinking to the fact that only executable
> files can be infected. (Word and Excel files, which civilians think of
> as textual only -- are actually executable -- I'll get to that in a
> minute) JPG and TIFF files themselves cannot be infected with a virus.
> But that's not to say a virus infecting an executable can't erase your
> entire hard drive. Fortunately, those viruses are extremely rare.
>
>> Many - if not most - may be
>> carried by or within textual files,
>
> No, not pure text files (files that only contain ASCII or UNICODE
> data). But Microsoft Word, Excel, and Outlook email are not pure text
> files. They can have Visual Basic programs attached to them, and you
> can write viruses in Visual Basic just like any other programming
> language. But this is impossible with JPEG and TIFF files. I'm not
> saying that you couldn't physically append the binary data of a virus
> written in C++ to a JPEG file, but it wouldn't do the would-be hacker
> any "good", because JPEG interpreters would see the tack-on as
> invalid data and would simply refuse to display the file, or display
> it corrupted, and no harm would be done.
>
> It would be possible to write a virus in a Postscript or PDF file, but
> I've never heard of that (yet).
>
> Frank Paris
> frankparis@comcast.net
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