I am doing some research that involves a *lot* of google searches. Because this research involves a significant number of directed queries, it seems logical to hide this information as much as practical. If there is a web host who notices sequential names in a Google referer URL repeatedly, this might raise suspicion or alter behavior which could skew results. Similarly, it is desirable to hide IP information from both the web host (for similar reasons) and possibly even search engines.

First, to avoid any changes to usual browsing, a new firefox profile was created using:

firefox -ProfileManager

Additionally, to run both firefox profiles at once, the first was run as normal, which the second has the additional options:

firefox -P <new-profile> -no-remote

I add this to my taskbar alongside the regular old firefox %u so I can choose a profile with a click.

To hide the HTTP referer, a firefox extension called RefControl was selected  https://addons.mozilla.org/en-US/firefox/addon/953. This simply replaces the referer for every query with one that is configurable. Although this is certainly possible with a more traditional proxy (like paros), RefControl’s ease of use is essential with the shear number of queries that were performed for this research. For this research, I changed the referer passed several times from names like “yahoo.com”, “cnn.com”, etc. Although the traffic patterns may still seem suspicious to an administrator who carefully monitors his logs, it reveals virtually no information about what it is that is being searched for.

To obfuscate the IP address, tor and privoxy were used. Tor bounces the HTTP requests around a distributed network of relays all around the world. An in depth discussion of Tor is out of the context here, but in a nutshell “it prevents somebody watching your Internet connection from learning what sites you visit, and it prevents the sites you visit from learning your physical location” http://www.torproject.org/. Privoxy is additionally used to prevent applications like flash or dns from leaking information. Since both privoxy and tor are required, you need to install these:

apt-get install tor privoxy

and to get privoxy to work with tor, I uncommented the following line (if it’s not there just add it):

forward-socks4a / localhost:9050 .

Despite the advantages, this did make browsing for names quite slow. I really like torbutton. In the not so distant future I remember having to modify proxy settings every time I wanted to go back and forth using tor. With tor

Lastly, the noscript firefox plugin was used to mitigate all javascript based attacks that might be used to obtain IP information http://noscript.net/.

One problem in particular is php. suexec was built for cgi-bin stuff – but php is a whole other beast. That’s what I’m talking about here – getting php to run as the user who owns it. More specifically, this will show how /home/user/public_html/myphp.php will run as “user”, but stuff in /var/www will still run as www-data.

One good article I found describing this is here: http://alain.knaff.lu/howto/PhpSuexec/

First things first – mod_php needs to be disabled. This can be done globally, but it’s better to just disable it for public_html dirs. This can be done by adding the following to /etc/apache2/apache2.conf.

<Directory /home>
 php_admin_flag engine off
</Directory>

Now, to enable suphp.

First install php-cgi. and the apache2 prefork which has some things we’ll need later on.

apt-get install php-cgi apache2-prefork-dev

Do not install libapache2-mod-suphp – at least not on 8.04. This older version lacks some of the things most people need… like having more than one directory.

Download the latest suphp module from http://www.suphp.org/Home.html.  Compile this like:

tar xfzv suphp-SNAPSHOT-2008-03-31.tar.gz
cd suphp-SNAPSHOT-2008-03-31
./configure --with-apxs=/usr/bin/apxs2 --with-setid-mode=owner
make
make install

Modify apache’s config

LoadModule suphp_module /usr/lib/apache2/modules/mod_suphp.so
<Directory /home>
AddHandler application/x-httpd-php .php .php3 .php4 .php5 .phtml
suPHP_AddHandler application/x-httpd-php
suPHP_Engine on
</Directory>

Now in /usr/local/etc/suphp.conf

[global]
webserver_user=www-data
docroot=${HOME}/public_html
check_vhost_docroot=false

[handlers]
;Handler for php-scripts
application/x-httpd-php="php:/usr/bin/php-cgi"

Restart apache. To debug, check /var/log/apache2/errors.log.  To test create scripts in public_html directories and in /var/www that exec(‘whoami’) and make sure they’re called with the correct permissions.

It’s a start, but then there’s always stuff like XSS, etc.

Probably due to the huge number of default programs (eg web browser, gnome text editor, console text editor, flash plugin, ftp programs, the list goes on.. ) they decided to put this junk in etc instead, and have this directory full of symbolic links.  So editor is actually set in /etc/alternatives as a symbolic link.

blah@debian:/etc/alternatives$ ls -l editor
lrwxrwxrwx 1 root root 9 2008-08-27 17:28 editor -> /bin/nano

Anyway, to change these values you can either change where the links point or use the update-alternatives command.  So to change the default text editor to vim in Ubuntu, you could

update-alternatives –config editor

Then select vim.