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Re: intercept nt/2k kernel api?

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On Tue, 20 Apr 2004 01:50:15 -0700 "Oleg K.Artemjev" <olli@xxxxxxxxx>
>Hello, folks.
>I've mostly teoretical questions, please excuse possbile mistakes/stupidity,

> since I'm not
>using windows oftenly & I'm not a programmer, just a person who
>wish to understand some
>security-related things, currently, I'm interested in brief understanding
>of nt/2k
>rootkit builder problems.
>Say, I'm already running in w2k as a vxd or so. AFAIK this is kernel
>mode. The questions are as follows:

First note, you probably mean sys as opposed to vxd.  These really aren't
supposed to be used in the newer releases of Windows
>*. Can I already being in kernel mode intercept Zw* and Nt* functions?

Yes, fairly easily actually.  Greg Hoglund has some sample code on rootkit.com
(the basic files) that will do exactly this.  Most of the time you are
going to want to inercept the Zw calls.

>*. Can I write to kernel memory being in kernel mode (executable

Yes, but it isn't trivial.  Device\\PhysicalMemory is probably what you
are going to want to play with.  Even with this, you still have to figure
out the physical-virtual mappings to really do what you are asking. Theres
a phrack article on this: Playing with windows /dev/(k)mem (phrack 59-

>*. Can I write to kernel memory belonging to another vxd or kernel
>itself (data memory)?
>*. What are problems I'll meet to do so? (guess, but donno why -
> at least it'll be address to play w/
>    for particular function, but mebbe)

Lots of blue screens ;)

>*. Does M$ really use non-executable flag for pages in XP service
>pack 2 for XP kernel and system    applications on new amd 64bit

Not sure, if they do it doesn't work ;)
>I'd be glad to see any good urls with overview of answers on above
>questions. Feel free to deny a post if it's out of topic for vuln-

www.rootkit.com & google searches on windows + rootkits
>Bye.Olli.			http://olli.digger.org.ru
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