Re: Buffer overflow in Explorer.exe

[Ryan Yagatich <ryany () pantek com>]

Hi, 
        I don't quite understand the purpose behind this code. It creates
a read only file '/aT4r[at]3WDesign.es Security/desktop.ini' with the
contents of

[.ShellClassInfo]
AAAAAAAAAAAA {x2301}


        And then terminates? I don't have a windows machine available to
really explore this any, but what makes that entry in desktop.ini cause
this? Furthermore, is this issue only for that particular key or is it
generally just key/excessive parameter/missing value size that is
affected? And additionally, you mention that explorer will no longer be
able to operate when trying to browse the hard disk, but does this mean
globally, or when they try to browse the c:/ drive, or just that
particular folder?
        Please send me more information about this, (even if it references
past posts that I have missed) so that I can better understand the
severity of this. Espcially since to me, I still see it as someone needing
to download and execute untrusted software which causes a system crash, 
and if that were going to happen there are far worse things that can be 
done besides creating a small text file.

Thanks,
Ryan Yagatich


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\ Ryan Yagatich                     support () pantek com \
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On Wed, 7 May 2003, aT4r InsaN3 wrote:

> This bug allow a malicious an attacker to execute data with privileges of a 
> user that is browsing the hard disk with explorer.
>
> tested against winxp SP1
>
> example code provided.
<snip>
>       strcpy(path,"\\aT4r[at]3WDesign.es Security");
>       mkdir(path);
>       SetFileAttributes(path,FILE_ATTRIBUTE_READONLY);
>
>       strcat(path,"\\desktop.ini");

>       bof=fopen(path,"w");
>       fputs("[.ShellClassInfo]\n",bof);
>       memset(evil,'A',BUFF);
>       fputs(evil,bof);
>       fclose(bof);
<snip>