Re: exploits for client side attacks not work

[Atul Agarwal <atul () secfence com>]

Hello,

Yes, only encoding the payload is not going to help you.

As an example, in order to make the exploit undetectable, you will have to
obfuscate the javascript that triggers the exploit (which is valid for most
PDF exploits - geticon(), newplayer() et al, libtiff doesn't utilise js for
exploitation).

Obfuscating the javascript is not particularly difficult, and you can use
publicly available js packers for the same (eg.
http://dean.edwards.name/packer/, <- heavily used). As they are public, bear
in mind, most AV's will flag it. Developing a custom javascript packer is
also not much difficult. Also, you could pack the js again and again using
same or different packers.

A nice place to find obfuscated js exploits is the exploit packs, which you
can get at any "underground" forum. Also keep checking the MDL (
http://malwaredomainlist.com/) for samples. Look into them.

Another approach to make the PDF exploits undetectable is to chain the
stream filters. Refer to
http://blog.didierstevens.com/2008/05/19/pdf-stream-objects/ for details.

I know, all the above will have to be done manually, outside metasploit. But
hey, metasploit is available to the AV guys too, and they can always
generate the samples and add signature/heuristics to the ways available in
the msf. So you will have to think differently.

Hope it helped.


Thanks,
Atul Agarwal
Secfence Technologies


On Mon, Jun 21, 2010 at 8:09 PM, Rob Fuller <mubix () room362 com> wrote:

> AVs are flagging on the exploited function (or should be), which is
> the basis for the exploit. Encoding the payload a million times will
> not help you. You are welcome to try for yourself though.
>
>
>
> --
> Rob Fuller | Mubix
> Room362.com | Hak5.org
>
>
>
> On Mon, Jun 21, 2010 at 9:17 AM, Spring Systems <korund () hotmail com>
> wrote:
> > PDF exploits for client side attacks not work at all, due 100% detection
> by
> > AVs as exploits.
> > This PDF will be useless unless Metasploit change payloads encoding
> scheme,
> > allowing to select verious encoding options
> > during the exploit creation.
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