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Attacking the Windows 7/8 Address Space Randomization

Posted on January 26th, 2013 at 15:59 by John Sinteur in category: Microsoft -- Write a comment


The nuts and bolts of what is presented here is the idea that DLLs are loaded into memory space if there is memory available, and if there is no memory or only small amounts of memory available then the DLL will be put into the remaining memory hole. This sounds simple. And it works, we can load a DLL into a remaining memory hole. First of all the exploit writer has to code a javascript routine that does fill memory until the memory boundary is hit and a javascript exception is raised. When the memory is filled up the installed javascript exception handler will execute javascript code that frees small chunks of memory in several steps, each step the javascript code will try to load an ActiveX object. The result is that the DLL (sometimes there are several DLLs loaded for an ActiveX object) will be loaded at a predictable address. This means that now the exploit writer has a predictable address to jump to and the ‘where do i jump when I have code execution’ problem is solved. One problem the method has is that Windows will become unresponsive at the time memory is exhausted but will resume normal operation after the DLL is loaded at a fixed address and the memory is freed using the javascript code.

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