IoT – CoreConduit Consulting Services

Keep Fingers Out of your Pi

Published on November 4, 2016 by coreconduitLeave a comment

In my previous article , I explain how to setup the Raspberry Pi to be a web server. I also demonstrate searching log files for “footprints” from the IP requests that have been made to your web server. Now, I would like to discuss protecting your web server from becoming a victim to a potentially malicious attack.

Keep your Pi updated!

sudo rpi-update

The command will automatically update the Raspberry Pi’s firmware and then ask for a reboot. If your Pi is already up-to-date, then you can continue with:

sudo apt-get update
sudo apt-get upgrade

Now, you’ve got the latest and greatest firmware and software!!

Pi Passwords

Ideally, we would disable the default pi account, at the very least, set the default password for your pi account. Another major in-security is that most users have SSH (Secure Socket sHell) and VNC (Virtual Networking Computer) enabled so that they can remote into their machines. I don’t recommend allowing access outside of your network when running a publicly exposed web server.

Apache Web Server

If you are serving web content world-wide then you’ll eventually want to adopt some sort of blacklist, or exclusion list, where you can keep specific IP addresses from accessing your server. However, if you want to tighten-down your security and only allow a select few access then you’ll need to make some changes.

cd /etc/apache2
sudo cp apache2.conf apache2.conf.bak
sudo vi apache2.conf OR sudo nano apache2.conf

Travel down the file until you reach this section that allows everyone access to your web server from the outside:

<Directory /var/www/>
 Options Indexes FollowSymLinks
 AllowOverride None
 Require all granted
</Directory>

The AllowOverride directive is set to None meaning we will not be using an .htaccess file to override these settings. The next directive, Require is set to all granted, meaning allow anyone access.

UPDATE: I have found a significant number of bot requests in my log files, snooping for those of Us using phpmyadmin, be sure to limit access:

<Directory /usr/share/phpmyadmin/>
Order Deny, Allow
Deny from All
# localhost
Allow from 127.0.0.1
# Local-Area Network
Allow from 192.168.x.x
</Directory>

Next, we can add a directory that we want to protect:

<Directory /var/www/html/hydroMazing/>
 Options Indexes FollowSymLinks
 AllowOverride All
</Directory>

The AllowOverride directive is set to All meaning we will be using an .htaccess file to override these settings. We will provide the Require directive in our .htaccess file inside the directory we specified, in this case, “/var/www/html/hydroMazing/” One last setting of importance before we save:

# AccessFileName: The name of the file to look for in each directory
# for additional configuration directives. See also the AllowOverride
# directive.
#
AccessFileName .htaccess

You could change the name of the .htaccess file here to something harder to guess. Keep the dot at the beginning because it means hidden file. Use your imagination 😉 Now you can use an .htaccess file as your whitelist, or inclusion list:

To create a .htaccess ( or whatever you’ve named it ) file:

cd /var/www/html/mydirectory/

sudo vi .htaccess OR sudo nano .htaccess

# Allow access to localhost 
Require ip 127.0.0.1

# Allow access to my cell phone
Require ip 98.97.34.23

Second entry is an example, change it to your IP address, or the IP address that your web server logged. See my previous article for instructions on checking your log files. Save and close the file. You can add additional access as desired.

Build a Wall

Install the open-source firewall builder

Pop open a terminal from your Raspberry Pi’s desktop and type the following:

sudo apt-get install fwbuilder

After the installation has completed, you will have a new option under the Menu/Internet option from your desktop for the firewall builder GUI.

Add a new firewall and name it the same as your server.

Select the “web server” template to load default rules.

Note that the default rules restrict your server from accessing the outside Internet. In order to allow access, you’ll need to add a rule. The easiest way to add a rule is to copy an existing rule that is similar to your needs.

Compile and Install

We can build our firewall through this interface, but we won’t be able to install it because we won’t have sufficient permissions to write to the file system. Enter the following at a terminal window’s command line assuming you named your server the same as your DDNS name:

sudo mkdir /etc/fw
sudo touch /etc/fw/servername.ddns.net.fw
sudo chmod 777 /etc/fw/servername.ddns.net.fw

Now, you should be able to use the firewall builder program to compile and install the firewall. You can either restart the apache web server or simply reboot.

Anything incorrect, missing, or not working? Please let me know.

Security through Obscurity

Published on November 1, 2016 by coreconduitLeave a comment

Security and Obscurity

“In security engineering, security through obscurity (or security by obscurity) is the reliance on the secrecy of the design or implementation as the main method of providing security for a system or component of a system. A system or component relying on obscurity may have theoretical or actual security vulnerabilities, but its owners or designers believe that if the flaws are not known, that will be sufficient to prevent a successful attack. Security experts have rejected this view as far back as 1851, and advise that obscurity should never be the only security mechanism.” https://en.wikipedia.org/wiki/Security_through_obscurity

We often rely on our security being through some sort of obscurity. “If they don’t know about it, they can’t use it to get in.” Common household door locks only have so many combinations, yet we can rely on the lock of our front doors because we know that a thief would have to try every combination or break-the-door-down. However, on the Internet, who is watching your front door, so a thief cannot try every combination? Fortunately, our web-server has an access.log file that is automatically updated and archived for us. Let’s start there and see if anyone has left their “footprints” on your web server.

Is anyone trying to gain access?

If you are running a LAMP setup on a Raspberry Pi , open-up a terminal window and type in the following:

cd /var/log/apache2/

zcat access.log* | awk '{print $1}' | sort -n | uniq -c | sort -nr | head -20

The output should be a list with two columns, one containing the number of entries counted, and the second column is the IP address associated with each web request made. The easiest way to get the most information from a reverse IP lookup is by using the following command:

curl ipinfo.io/REPLACE.WITH.IP.ADDRESS.TO.LOOKUP

Rather than rely on an external web service, you can do some digging after you install some tools that are not included by default with the Pi:

sudo apt-get install geoip-bin
geoiplookup IP.ADDRESS

Here is a good article on using geoiplookup. Even more advanced digging not included by default with the Pi:

sudo apt-get install dnsutils
dig -x IP.ADDRESS

Does the location seem suspicious? Try grepping for the activity, the zgrep command includes the compressed files:

zgrep 'IP.ADDRESS' access.log* -1

By looking at the web requests that were made from the IP address, you can determine whether the activity is suspicious. Typically, you will find that these IP addresses are from bots looking for vulnerabilities in your security. You can manually block IP addresses to your blacklist or you can just deny all and allow select IP addresses. If you haven’t already, you’ll want to install and setup a firewall.

Power to the People!

Published on June 14, 2016 by coreconduitLeave a comment

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Tag: IoT