OT: Virii

From: Carlos Murillo <cmurillo_at_emtelsa.multi.net.co>
Date: Wed Jul 18 21:57:54 2001

Yes, but contiguous 0's are special and easy enough
to detect, and, it would not be difficult for the assembler
to include some initialization code. In the end, this is a
difference in philosophy, asm vs. higher level languages.
You don't expect an assembler to optimize that sort of thing,
but rather, to do exactly as it is told.

Now, I remember when g77 would actually include the
image of a zero-initialized array within a common block
in the executable.... at one point I had a 130MB
executable :-) . This is the opposite case, a high-level
language not optimizing that sort of thing.

Carlos.

At 06:37 PM 7/18/01 -0700, you wrote:
>On Wed, 18 Jul 2001, Sean 'Captain Napalm' Conner wrote:
>> some_buffer db 4096 dup(0)
>> end segment
>
>That EXPLICITLY calls for 4K of 0's.
>Virtually no assembler is clever enough to do a run-length compression.
>OTOH, If you wrote
> some_buffer db 4096 dup (?)
>it would set up 4K of "UNINITIALIZED" space, which it COULD compress out
>of the file, particularly if it is at the end.
>
>> . . . So it would be easy enough for a virus to scan the
>> executable for a portion that is nothing but zeros, and hide in there.
>It could always make space within the MICROS~1 copyright message.
>
>--
>Grumpy Ol' Fred cisin_at_xenosoft.com
>
>
--------------------------------------------------------------
Carlos E. Murillo-Sanchez carlos_murillo_at_nospammers.ieee.org
Received on Wed Jul 18 2001 - 21:57:54 BST