From: Berend-Jan Wever (berendjanwevergmail.com)
Date: Sat Jan 02 2010 - 14:48:40 CST

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One limitation of most alphanumeric shellcode decoders, including those in *
ALPHA2<http://skypher.com/wiki/index.php/Hacking/Shellcode/Alphanumeric/ALPHA2>
* and the soon-to-be-released
*ALPHA3<http://skypher.com/wiki/index.php/Hacking/Shellcode/Alphanumeric/ALPHA3>
* is that they need to know where they are located in memory in order to
decode themselves and run correctly. This makes using a *nopslide* hard in
most circumstances, because you mostly only need a *nopslide* if you do not
know exactly where your shellcode is in memory to begin with.

I've developed a way to get around this problem, which I've described in
more detail here:
http://skypher.com/index.php/2010/01/02/countslide-alphanumeric-getpc/

ALPHA3 has support for generating working alphanumeric shellcode with
nopslides using this technique. I'm currently working on getting the rest of
its code into releasable shape.

Cheers,
SkyLined
 <http://skypher.com/index.php/2010/01/02/countslide-alphanumeric-getpc/>
Berend-Jan Wever <berendjanwevergmail.com>
http://skypher.com/SkyLined

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