[WEB4LIB] Re: two questions on viruses

[John Fitzgibbon]

Hi Thomas,

Thanks for your reply.

The /B switch works as you said.

When I copy the two programs into one file, the resultant file does not
launch both programs in quick succession it merely launches the first
program. The code in a virus would have to run after the program is run
or is a virus always copied onto the start of a program and never at the
end?

Regards
John


-----Original Message-----
From: web4lib at webjunction.org
[mailto:web4lib at webjunction.org] On Behalf Of Thomas Bennett
Sent: 07 January 2005 15:49
To: Multiple recipients of list
Subject: [WEB4LIB] Re: two questions on viruses

If your PCs are not running a firewall to block other ports incoming
then there is always a potential especially with MS Windows.

The copy command, on MS Windows, allows /A for ascii and /B for binary. 
You can copy an ascii file to binary or a binary file to ascii.  I think
the default is ascii in which case when you copy the binary file using
the ascii mode the file will probably end at the first EOF (end of file)
character and truncate the rest of the file.  If I remember correctly
eof is 0E 0A (hex) which is not an EOF in a binary file.  If you copy
those to files together using /B you should something closer to the sum
of their sizes.


Thomas


COPY /?

COPY [/V] [/N] [/Y | /-Y] [/Z] [/A | /B ] source [/A | /B]
     [+ source [/A | /B] [+ ...]] [destination [/A | /B]]

  source       Specifies the file or files to be copied.
  /A           Indicates an ASCII text file.
  /B           Indicates a binary file.
  destination  Specifies the directory and/or filename for the new
file(s).
  /V           Verifies that new files are written correctly.
  /N           Uses short filename, if available, when copying a file
with a
               non-8dot3 name.
  /Y           Suppresses prompting to confirm you want to overwrite an
               existing destination file.
  /-Y          Causes prompting to confirm you want to overwrite an
               existing destination file.
  /Z           Copies networked files in restartable mode.


On Fri, 2005-01-07 at 06:20, John Fitzgibbon wrote:
> Hi,
> 
> Some of our PCs make the library catalogue available (a web site) and
> only the library catalogue available to the public. It is not possible
> to access any other web site or run any Office program on these PCs.
Can
> these PCs become infected by a virus or worm? There is no anti-virus
> software running on them.
> 
> Secondly, I read that a virus attaches itself either to the beginning
or
> end of a program and launches itself when that program is run. As an
> experiment, I took two programs, Notepad.exe and NoteTab.exe: I copied
> them into one file using a DOS command. The result is a much smaller
> file than the sum of its parts which does not launch the two programs
in
> quick succession, as I expected. Any ideas on why this might be so?
> 
> Regards
> John
> 
> John Fitzgibbon
> 
> Galway Public Library
> Island House
> Cathedral Square
> Galway
> Ireland
> 
> p: 00 353 91 562471
> f: 00 353 91 565039
> w: http://www.galwaylibrary.ie
> 
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Má tá an ríomhphost seo faighte agat trí dhearmad, 
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agus scrios ansin é le do thoil. 

This e-mail and any attachment contains information which is 
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