====== Apache - Modules - Install mod_security and mod_evasive ======

**ModSecurity** is a toolkit for real-time web application monitoring, logging, and access control.

**mod_evasive** is an evasive manoeuvres module for Apache to provide evasive action in the event of an HTTP DoS or DDoS attack or brute force attack.

    * It is also designed to be a detection and network management tool, and can be easily configured to talk to ipchains, firewalls, routers, etc.
    * It reports abuses via email and syslog facilities.

----

===== Install ModSecurity =====

To install [[http://www.modsecurity.org/|ModSecurity]].

Install the dependencies.  Execute the following commands:

<code bash>
sudo apt-get install libxml2 libxml2-dev libxml2-utils
sudo apt-get install libaprutil1 libaprutil1-dev
</code>

<WRAP info>
**NOTE**:  64bit users:

  * Because of [[http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=670248|this bug]] you need to create a symbolic link to **libxml2.so.2** or the installation will report the file missing and fail.

<code bash>
ln -s /usr/lib/x86_64-linux-gnu/libxml2.so.2 /usr/lib/libxml2.so.2
</code>

</WRAP>

----

===== Install ModSecurity =====

<code bash>
sudo apt-get install libapache-mod-security
</code>

----

===== Configure ModSecurity rules. =====

Activate the recommended default rules to get things going.

  * Configure as required.
  * For complete information see [[http://www.modsecurity.org/documentation/modsecurity-apache/2.5.9/modsecurity2-apache-reference.html|ModSecurity Reference Manual]].

<code bash>
sudo mv /etc/modsecurity/modsecurity.conf-recommended /etc/modsecurity/modsecurity.conf
</code>

<WRAP info>
**NOTE:**  The default folder for ModSecurity rules is **/etc/modsecurity/**.

  * All .conf files will be included and need to be configured as required.

</WRAP>

----

===== Activate all the base rules and make sure they also get loaded =====

Optionally edit the **SecRequestBodyLimit** option in the modsecurity.conf file.

  * **SecRequestBodyLimit** limits the page request size and limits file uploads to **128 KB** by default.
  * Change this to the size of files you would accept uploaded to the server.

<WRAP info>
**NOTE:**  This settings is very important as it limits the size of all files that can be uploaded to the server.

  * For CMS sites using Drupal or Wordpress this setting is the source of much pain. 

</WRAP>

Execute the command:

<code bash>
sudo vi /etc/modsecurity/modsecurity.conf
</code>

First activate the rules by editing the **SecRuleEngine** option and set to On and modify your server signature.

<file bash /etc/modsecurity/modsecurity.conf>
SecRuleEngine On
SecServerSignature FreeOSHTTP
</file>

Edit the following to option to increase the request limit to 16 MB and save the file:

<file bash /etc/modsecurity/modsecurity.conf>
SecRequestBodyLimit 16384000
SecRequestBodyInMemoryLimit 16384000
</file>

----

===== Download and install the latest OWASP Core Rule Set =====

The goal of the **OWASP ModSecurity CRS Project** is to provide an easily "pluggable" set of generic attack detection rules that provide a base level of protection for any web application.

Download and install the latest [[https://www.owasp.org/index.php/Category:OWASP_ModSecurity_Core_Rule_Set_Project|OWASP ModSecurity Core Rule Set]] from the project website.

  * See [[https://www.owasp.org/index.php/Category:OWASP_ModSecurity_Core_Rule_Set_Project|here]] for more information.

Also activate the default CRS config file **modsecurity_crs_10_setup.conf.example**.

If you prefer not to use the latest rules, replace the wget for master below with the a specific version you would like to use e.g : **v2.2.5**.
  
Execute the following commands:

<code bash>
cd /tmp
sudo wget -O SpiderLabs-owasp-modsecurity-crs.tar.gz https://github.com/SpiderLabs/owasp-modsecurity-crs/tarball/master
sudo tar -zxvf SpiderLabs-owasp-modsecurity-crs.tar.gz
sudo cp -R SpiderLabs-owasp-modsecurity-crs-*/* /etc/modsecurity/
sudo rm SpiderLabs-owasp-modsecurity-crs.tar.gz
sudo rm -R SpiderLabs-owasp-modsecurity-crs-*
sudo mv /etc/modsecurity/modsecurity_crs_10_setup.conf.example /etc/modsecurity/modsecurity_crs_10_setup.conf
</code>


Create symbolic links to all activated base rules.  Execute the following commands:

<code bash>
cd /etc/modsecurity/base_rules
for f in * ; do sudo ln -s /etc/modsecurity/base_rules/$f /etc/modsecurity/activated_rules/$f ; done

cd /etc/modsecurity/optional_rules
for f in * ; do sudo ln -s /etc/modsecurity/optional_rules/$f /etc/modsecurity/activated_rules/$f ; done 
</code>


Add these rules to Apache2.  Execute the following command:

<code bash>
sudo vi /etc/apache2/mods-available/mod-security.conf
</code>


Add the following to towards the end of the file with other includes and save the file:

<file bash /etc/apache2/mods-available/mod-security.conf>
Include "/etc/modsecurity/activated_rules/*.conf"
</file>

----

===== Check if ModSecurity is enabled and restart Apache =====

Before restarting Apache2 check if the modules has been loaded.

Execute the following commands:

<code bash>
sudo a2enmod headers
sudo a2enmod mod-security
</code>

----

Restart the Apache2 webserver:

<code bash>
sudo /etc/init.d apache2 restart
</code>

or

<code bash>
service apache2 restart
</code>

----

===== Test ModSecurity =====

To test mod_security you can use curl to send HTTP requests to the Apache server.  One of the ModSecurity default rules is to reject requests that have a User Agent of "Nessus".  This is intended to deny information to attackers who use automated scanners.

You can check mod_security by running the following command:

<code bash>
sudo curl -i http://192.168.1.42/ -A Nessus
</code>

You should see a **403 Forbidden** response, as shown below on this page. ModSecurity has blocked the request, because the User Agent identifies it as a Nessus scan.

<code>
HTTP/1.1 403 Forbidden
Date: Tue, 27 Oct 2015 11:08:39 GMT
Server: Apache
X-Frame-Options: SAMEORIGIN
Last-Modified: Thu, 16 Oct 2014 13:20:58 GMT
Accept-Ranges: bytes
Content-Length: 4897
X-XSS-Protection: 1; mode=block
Content-Type: text/html; charset=UTF-8
</code>

----

===== Install ModEvasive =====

Install [[http://www.zdziarski.com/blog/?page_id=442|ModEvasive]]

Execute the following:

<code bash>
sudo apt-get install libapache2-mod-evasive
</code>

----

===== Create log file directory for mod_evasive =====

Execute the following:

<code bash>
sudo mkdir /var/log/mod_evasive
</code>


Change the log folder permissions:

<code bash>
sudo chown www-data:www-data /var/log/mod_evasive/
</code>

----

===== Create mod-evasive.conf file and configure ModEvasive =====

Execute the following:

<code bash>
sudo vi /etc/apache2/mods-available/mod-evasive.conf
</code>

Add the following, changing the email value, and other options below as required:

<file bash /etc/apache2/mods-available/mod-evasive.conf>
<ifmodule mod_evasive20.c>
   DOSHashTableSize 3097
   DOSPageCount  2
   DOSSiteCount  50
   DOSPageInterval 1
   DOSSiteInterval  1
   DOSBlockingPeriod  10
   DOSLogDir   /var/log/mod_evasive
   DOSEmailNotify  EMAIL@DOMAIN.com
   DOSWhitelist   127.0.0.1
</ifmodule>
</file>

----

===== Fix mod-evasive email bug =====

Because of [[https://bugs.launchpad.net/ubuntu/+source/libapache-mod-evasive/+bug/605679|this bug]] mod-evasive does not send emails on Ubuntu 12.04.

A temporary workaround is to create a symlink to the mail program.

Execute the following:

<code bash>
sudo ln -s /etc/alternatives/mail /bin/mail/
</code>

----

===== Check if ModEvasive is enabled and restart Apache =====

Before restarting Apache2 check if the module has been loaded.

Execute the following:

<code bash>
sudo a2enmod mod-evasive
</code>


Restart the Apache2 webserver:

<code bash>
sudo /etc/init.d/apache2 restart
</code>

or

<code bash>
service apache2 restart
</code>

----

===== Test ModEvasive =====

You can test mod_evasive by using the Perl **scripttest.pl** written by the Mod_Evasive developers.

Before running this script, you need to make some changes:

<code bash>
sudo vi /usr/share/doc/mod_evasive-1.10.1/test.pl
</code>

Find the line **for(0..100) {** Replace **100** with **200**.  Find the line **PeerAddr=> "127.0.0.1:80");** Replace **127.0.0.1** with **yourserverip (192.168.1.42)**.

<file perl /usr/share/doc/mod_evasive-1.10.1/test.pl>
#!/usr/bin/perl
# test.pl: small script to test mod_dosevasive's effectiveness

use IO::Socket;
use strict;

for(0..200) {
  my($response);
  my($SOCKET) = new IO::Socket::INET( Proto   => "tcp",
                                  PeerAddr=> "192.168.1.42:80");
  if (! defined $SOCKET) { die $!; }
  print $SOCKET "GET /?$_ HTTP/1.0\n\n";
  $response = <$SOCKET>;
  print $response;
  close($SOCKET);
}`
</file>

Save and exit.

Now, run the script:

<code bash>
sudo  /usr/share/doc/mod_evasive-1.10.1/test.pl
</code>

You should see the following output:

<code>
HTTP/1.1 403 Forbidden
HTTP/1.1 403 Forbidden
HTTP/1.1 403 Forbidden
HTTP/1.1 403 Forbidden
HTTP/1.1 403 Forbidden
</code>

ModEvasive also logs to syslog when the IP address is blocked.  You can check the log file using:

<code bash>
sudo tailf /var/log/messages
</code>

You should see the following output:

<code>
Oct 26 15:36:42 CentOS-7 mod_evasive[2732]: Blacklisting address 192.168.1.42: possible DoS attack.
</code>

----