On Wed, 20 Oct 2004, Thor Larholm wrote:
Hello Thor,
When
IE renders an IMG element it gives priority to the SRC attribute but
when IE drops an IMG element on an arbitrary window it gives priority to
the DYNSRC attribute. If you are able to reference any local content you
can therefore drop the DYNSRC attribute of the IMG element on the window
with local content and thereby plant a file on the file system in a
known location.
Sorry that I do not understand your very interesting explanations.
I examined http-equivs demo, but he isn't using the DYNSRC attribute
anywhere near the drag&drop part.
The only file containing "dynsrc" is his pseudo database foobar.txt, which
is used in the last stage of the exploit, to download "code".
His drop source is included with a simple
<img src="malwarez" width="30" height="30" style="cursor:hand" title="drag
me!">
Absolutely no DYNSRC here.
So the question stays: malwarez carries no extension, it is a valid GIF
image, but when it is dropped, it is named "malwarez[1].htm"
The only explanation I have, is that the server declares
malwarez to be HTML:
# wget -S http://www.malware.com/malwarez
--18:41:25-- http://www.malware.com/malwarez
=> `malwarez'
1 HTTP/1.0 200 OK
...
8 Content-Type: text/html
^^^^
So IE just uses the Content-Type to name this file.
bye, ju
--
Juergen Schmidt Chefredakteur heise Security www.heisec.de
Heise Zeitschriften Verlag, Helstorferstr. 7, D-30625 Hannover
Tel. +49 511 5352 300 FAX +49 511 5352 417 EMail ju@heisec.de
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