Security through obscurity – hiding your server version information

I’ve recently spent a lot of time reviewing the OWASP documentation, and (like many corporations) realized that I’d neglected to keep up with this configuration item.

By sharing the exact version of each piece of server software you are using, “hackers” are able to quickly identify unpatched systems and their known vulnerabilities.

To make their work harder, there are a few simple steps that the server admin can take to remove this information from the HTTP Headers and error pages.

Apache HTTPd:

  1. sudo vi /etc/apache2/conf-enabled/security.conf
  2. Add:

    ServerTokens ProductOnly
    ServerSignature Off
  3. If using virtual hosts, add the following to each one:
    ServerSignature Off
  4. sudo service apache2 restart

Apache Tomcat:

  1. vi /opt/tomcat7/conf/server.xml
  2. Find the <Connector > entry and add:
    server="Apache"
  3. cd /opt/tomcat7/lib
  4. mkdir -p org/apache/catalina/util
  5. vi /opt/tomcat7/lib/org/apache/catalina/util/ServerInfo.properties
    server.info=Apache Tomcat
  6. sudo service tomcat7 restart

PHP “X-Powered-By: PHP/5.x.x-1ubuntuX.X”

  1. sudo vi /etc/php5/apache2/php.ini
    expose_php = Off
  2. sudo service apache2 restart

REFERENCES:

Renaming JSESSIONID

Older versions of Apache Tomcat, as well as the older servlet specifications required that several configuration values need to be set. With servlet 3, you can now modify the name of the session cookie (as well as the ‘rewriting’ attribute name) in the web.xml file

In web.xml: (servlet 3.x)

<session-config>
<session-timeout>30</session-timeout>
<cookie-config>
<name>mysessionid</name><!-- default is jsessionid -->
<http-only>true</http-only>
<!-- secure>true</secure-->
</cookie-config>
<tracking-mode>COOKIE</tracking-mode>
</session-config>

Alternately for Tomcat7, modify TOMCAT_HOME\conf\context.xml:
<Context path="/exampleApp" sessionCookieName="myid">

If you are using spring security, then you should try setting disable-url-rewriting attribute of <http> element to true.

REFERENCES:

Install free “recognized” SSL certificates for Apache2

Once you have your server running with a self-signed certificate you might find it useful to have a “real” certificate that does not warn users.

Many of the CA’s provide test certificates that are generally valid for 30-60 days, I’ve recently discovered StartSSL, that generates free certificates that are valid for a full year.

  1. Generating keys and certificates….

    NOTE: this process is rather involved and is documented better elsewhere, here’s what I needed to remember to get the keys and certificates.

    • save ssl.key (private)
    • save ssl.crt (pem encoded)
    • get file from control panel: sub.class1.server.ca.pem
  2. Make sure that you move all three files to the /etc/apache2/ssl/ folder on the server.
  3. Edit the config file…
    sudo vi /etc/apache2/sites-available/default-ssl.conf

    Modify the values related to the keys and certs…

    SSLCertificateFile /etc/apache2/ssl/ssl.crt
    SSLCertificateKeyFile /etc/apache2/ssl/ssl.key
    SSLCertificateChainFile /etc/apache2/ssl/sub.class1.server.ca.pem

  4. Reload the config and restart…

    sudo service apache2 reload
    sudo service apache2 restart
  5. Test it out…
    https://www.ssllabs.com/ssltest/analyze.html?d=YOURDOMAIN.COM

REFERENCES:

Create self-signed SSL certificates for Apache on Ubuntu

To increase the security of your web applications, it is a standard process to enable HTTPS/SSL/TLS. Unfortunately, purchasing certificates can often be very expensive. Luckily, you can create a self-signed certificate for free for casual use or testing.

These steps are for Ubuntu, I wrote similar documentation for the Windows platform that you can find way back in my blog archives!

NOTE: As certificates generated in this manner are not verified by any recognized authority, many browsers will warn users (often in frightening language) about their insecurity. As stated above, these are best used only for internal use.

  1. First you will need to have apache2 installed, at a minimum you need to run:
    sudo apt-get install apache2
  2. Enable the SSL module:
    sudo a2enmod ssl

  3. Create the folder to store the keys and certificates:
    sudo mkdir /etc/apache2/ssl

  4. Generate a private key and certificate:

    sudo openssl req -x509 -nodes -days 365 -newkey rsa:2048 -keyout /etc/apache2/ssl/apache.key -out /etc/apache2/ssl/apache.crt

    Enter reasonable values for the fields in question.
    For FQDN Common Name enter *.domain.com for wildcard support!

  5. Edit the config file:

    sudo vi /etc/apache2/sites-available/default-ssl.conf

  6. Un-comment or update the following lines:

    ServerName YOURDOMAIN.COM
    ServerAlias WWW.YOURDOMAIN.COM
    SSLCertificateFile /etc/apache2/ssl/apache.crt
    SSLCertificateKeyFile /etc/apache2/ssl/apache.key

  7. Enable to SSL website and restart:

    sudo a2ensite default-ssl.conf
    sudo service apache2 reload
    sudo service apache2 restart

  8. Test it out… provided your firewall routes port 443 to your server.

    https://www.ssllabs.com/ssltest/analyze.html?d=YOURDOMAIN.COM

REFERENCES:

Problems uploading/deploying large WAR’s to Tomcat7?

I’ve run into this a few times as my web applications got larger. Often this has been seen when builds automated by Jenkins start failing as they increase in size. It has also occurred to me when doing manual deployments as the Jenkins WAR itself is larger than 50MB lately.

Let’s just go in and increase the maximum expected file size…

This change should work on any platform, but the following is from my experience with Ubuntu.

sudo vi /opt/tomcat7/webapps/manager/WEB-INF/web.xml

Default is:

<multipart-config>
<!-- 50MB -->
<max-file-size>62428800</max-file-size>
<max-request-size>62428800</max-request-size>
<file-size-threshold>0</file-size-threshold>
</multipart-config>

Change to something a bit larger (to your liking):

<multipart-config>
<!-- 50MB max 62428800, 100MB = 104857600 -->
<max-file-size>104857600</max-file-size>
<max-request-size>104857600</max-request-size>
<file-size-threshold>0</file-size-threshold>
</multipart-config>

Restart with either…
sudo /etc/init.d/tomcat7 restart
or
sudo service tomcat7 restart

Install Splunk Universal Forwarder on Ubuntu

After a while it can get tedious to access and review server logs via the command line. There are several tools available that can provide the same information in a graphical manner. Recently I’ve migrated to Splunk as there are both Enterprise and Free versions available.

  1. Of course, you’ll need a Splunk server installed first, as the forwarder is really just another (lighter) instance that will forward the log information to a central location.
  2. Download the system appropriate installer from:
    http://www.splunk.com/download/universalforwarder
  3. Check to see if you are running 32 or 64 bit OS.uname -aIf you see i686 you are 32 bit, if x86_64 you are 64 bit!
  4. Download, you’ll likely need a different version:sudo dpkg -i splunkforwarder-6.1.3-220630-linux-2.6-intel.deb
    or
    sudo dpkg -i splunkforwarder-6.1.3-220630-linux-2.6-amd64.deb
  5. Enable auto-start on reboot:cd /opt/splunkforwarder/bin/

sudo ./splunk enable boot-start

  1. Start the server:sudo service splunk start
  2. Set the password:

    The default ‘admin‘ password is ‘changeme‘ so we need to change it immediately to do anything else, or we will see errors in future steps.

    sudo /opt/splunkforwarder/bin/splunk edit user admin -password YOUR_NEW_PASSWORD -auth admin:changeme

  3. Set the server:sudo /opt/splunkforwarder/bin/splunk add forward-server YOUR_SERVER_ADDRESS:9997

    NOTE: if you get prompted for a splunk username/password you likely skipped the above step. Remember – the forwarder is a new ‘light’ installation of the server and as such has it’s own users!

  4. Enable some monitors on the box:Some common services and log locations to get you started…
    Apache2 HTTPd
    sudo /opt/splunkforwarder/bin/splunk add monitor /var/log/apache2 -index main -sourcetype Apache2
    Tomcat7
    sudo /opt/splunkforwarder/bin/splunk add monitor /opt/tomcat7/logs -index main -sourcetype Tomcat7
    MySQL
    sudo /opt/splunkforwarder/bin/splunk add monitor /var/log/mysql -index main -sourcetype MySQL
    Postfix (SMTP)
    sudo /opt/splunkforwarder/bin/splunk add monitor /var/log/mail.log -index main -sourcetype Postfix
    Squid3 (Proxy) 
    sudo /opt/splunkforwarder/bin/splunk add monitor /var/log/squid/access.log -index main -sourcetype Squid3
    sudo /opt/splunkforwarder/bin/splunk add monitor /var/log/squid/cache.log -index main -sourcetype Squid3

    SonarQube
    sudo /opt/splunkforwarder/bin/splunk add monitor /opt/sonar/logs -index main -sourcetype Sonar
  5. (OPTIONAL) Verify configuration by opening file at the following:sudo su
    vi /opt/splunkforwarder/etc/apps/search/local/inputs.conf
    exit
  6. You now should be able to log into your server and see new data flowing from the forwarder.

    NOTE: this requires you to enable ‘receiving’ of data on the port specified above, usually 9997.

REFERENCES:

Preventing Blackberry browser from messing up your UI

I’ve previously given steps to prevent phone numbers (and other elements) from being automatically reformatted by Skype Toolbar and IOS Safari, there is still a small segment of the user population that uses Blackberry devices that can similarly benefit from a little code.

The following stops auto detection and formatting of phone and email addresses on devices with the BlackBerry Browser.

HTML:

<meta http-equiv="x-rim-auto-match" content="none" />

WML:

<meta name="x-rim-auto-match" http-equiv="x-rim-auto-match" forua="true" content="none" />

REFERENCES:

Skype toolbar meta tag… preventing Skype from messing up your UI

I’ve previously documented the method used to prevent IOS devices from formatting numbers.

Users on other platforms, notably Windows, have Skype installed and it too can cause some headaches with your UI as it inserts elements to decorate phone numbers.

For users that have the Skype Toolbar enabled, the following META tag will prevent it from doing a lot of damage!

<meta name="SKYPE_TOOLBAR" content="SKYPE_TOOLBAR_PARSER_COMPATIBLE" />

REFERENCES:

HTML cleartype meta tag?

This tag allows for activation of ClearType in Mobile IE for smoothing fonts.


<!--[if IEMobile]><meta http-equiv="cleartype" content="on" /><![endif]-->

NOTE: Future use of this approach is questionable, as MSIE10 dropped support of conditional comments, and HTML5 validators (in general) do not “like” the http-equiv values as they are not standardized

REFERENCES:

Preventing IOS/Safari from formatting numbers

There are many cases where your application may display numbers that “resemble” phone numbers, but are not, unfortunately Safari’s default behavior is for it to be “helpful” and format them into clickable/callable links for the user of Apple IOS devices.

Adding the following META tag can prevent that default behavior:

<meta name="format-detection" content="telephone=no" />
.

NOTE: I’ve seen some mention of using this method for ‘address=no’ and ’email=no’, but have not looked into or verified those implementation yet!

REFERENCES: