> As far as I can tell, this is not exploitable to run a shellcode because
> of the fact that NULL's are inserted between charactors. But besides
This is not a problem, read phrack: unicode shellcodes are real.
In fact you can create your own unicode alphanumeric uppercase shellcode using ALPHA2:
http://www.edup.tudelft.nl/~bjwever/alpha2/alpha2.php
Cheers,
SkyLined
----- Original Message -----
From: "Jack C" <jack_at_crepinc.com>
To: <bugtraq_at_securityfocus.com>
Sent: Tuesday, November 09, 2004 03:24
Subject: BoF in Windows 2000: ddeshare.exe
> Hello all,
>
> I found a static buffer overflow in ddeshare.exe on my Windows 2000,
> latest updates/service packs box tonight. It appears as though no bounds
> checking is performed on the share name before it is copied to the variable.
>
> Exploiting:
> Start up c:\winnt\system32\ddeshare.exe. Click shares --> trusted
> shares. Pick any of the shares already there (at least there are some on
> my box, if not you can make one), and select Properties. Replace the
> data in the "Share Name" text box with something like this:
>
> AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAABB
>
> When you click OK, you get an error stating that ddeshare.exe has
> "generated errors". Yay.
>
> Run in OllyDbg, we find that the above string makes the program attempt
> to JMP to 0x00420042. It just so happens that Hex 42 is a "B". So the
> two B's at the end of the exploit string change the instrucation pointer.
>
> As far as I can tell, this is not exploitable to run a shellcode because
> of the fact that NULL's are inserted between charactors. But besides
> that, it would only give the same privliges that you already have to run
> the program in the first place. It simply points out bad coding.
>
> Again, this isn't another of Microsoft's giant end-of-the-world security
> blunders, but still, it's a BoF.
>
> Thanks,
>
> -Jack C ("crEp")
> jack [at] crepinc.com
> http://www.crepinc.com
>
Received on Nov 09 2004
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