OSEC

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Developing exploit for a tricky vulnerability

From: John Paterson (john9434gmail.com)
Date: Fri Jun 29 2007 - 06:31:36 CDT


Here is the scenario:
There is a buffer located on the heap beginning at address A. I can
overwrite any dword-aligned memory location between A and A+S, where S
is the size of exploit file divided by 2. This is the tricky part -
the value written must be in the range from 0 to FFFF. This is not a
typical heap overflow - in orther to overwrite location X I don't need
to overwrite all locations between A and X, I can overwrite just X.
Multiple locations can be overwritten with different values.
Target platform is Windows XP.
Any ideas how to exploit this?