"Secure" Word Press on Amazon Linux

WORK IN PROGRESS: Amazon only allows ssh access without a console, you can easily get yourself locked out.

Purpose

To run a simple wordpress site as "securely" as possible from the server side.

Non SELinux

When this was written, we started using PHP 7 and needed Apache 2.4. Neither of these are standard installs for Amazon Linux.

OS Prep

Create SWAP

• Create SWAP file (Cloud hosted instances lack these). The following will create a 6GB swap file.

sudo dd if=/dev/zero of=/SWAP bs=1024 count=6291453
sudo chmod 0600 /SWAP
sudo mkswap /SWAP
sudo swapon /SWAP

• Add the swap file to FSTAB

/SWAP swap swap defaults 0 0

Install packages

Feel free to install updated php, this section will be updated as further testing is done. Also note the time zone if you are on the east coast.

sudo yum -y update
sudo yum -y install fail2ban httpd24 mysql mysql-server php70 php70-mysqlnd mod24_ssl yum-cron php70-mbstring php70-zip htop
sudo yum -y install https://dl-ssl.google.com/dl/linux/direct/mod-pagespeed-stable_current_x86_64.rpm
sudo ln -sf /usr/share/zoneinfo/America/New_York /etc/localtime
sudo sed -i 's/update_cmd\ =\ default/update_cmd\ =\ security/' /etc/yum/yum-cron.conf

Hide Apache\PHP

sudo rm -f /etc/httpd/conf.d/welcome.conf
sudo sed -i 's/expose_php\ =\ On/expose_php\ =\ off/; s/upload_max_filesize\ =\ 2M/upload_max_filesize\ =\ 128M/; s/post_max_size\ =\ 8M/post_max_size\ =\ 64M/; s/max_execution_time\ =\ 30/max_execuion_time\ =\ 60/' /etc/php.ini

• Append /etc/httpd/conf/httpd.conf with

ServerTokens Prod
ServerSignature Off
LoadModule deflate_module modules/mod_deflate.so

Startup Services

• Make sure services are set to start at boot, then reboot.

sudo chkconfig fail2ban on
sudo chkconfig mysqld on
sudo chkconfig httpd on
sudo chkconfig yum-cron on
sudo reboot

Configure Database

• After reboot prep the database. Start with the standard secure installation. Password does not need to be super secure as this is not a shared database, or remotely accessible.

sudo mysql_secure_installation
[ec2-user@ip-172-26-8-112 ~]$ sudo mysql_secure_installation

Set root password? [Y/n] Y 
New password: 
Re-enter new password: 

Remove anonymous users? [Y/n] Y

Disallow root login remotely? [Y/n] Y

Remove test database and access to it? [Y/n] Y

Reload privilege tables now? [Y/n] Y

• Create the databse

mysql -uroot -p
create database wordpress;
grant all privileges on wordpress.* to 'wordpress'@'localhost' identified by 'password';
exit

Append the following to /etc/my.cnf in the mysqld section.

max_allowed_packet=32M

vhost Config

We do not want to use htaccess as this would allow bad modifications to be made if compromised. Instead we stick to vhost config files (It also performs better).

• Prep for using SSL. The following will provide a self signed cert that can be used for initial configuration of the site. When the URL is known, you will want to replace with a trusted cert. LetsEncrypt is a good resource for this.
• In the following example we have the Google Analytics modules commented out. Make sure to have your Analytics ID ready before enabling.

sudo mv /etc/httpd/conf.d/ssl.conf ./
sudo nano /etc/httpd/conf.d/vhost.conf

LoadModule ssl_module modules/mod_ssl.so
Listen 443
SSLPassPhraseDialog  builtin
SSLSessionCache         shmcb:/var/cache/mod_ssl/scache(512000)
SSLSessionCacheTimeout  300
SSLRandomSeed startup file:/dev/urandom  256
SSLRandomSeed connect builtin
SSLCryptoDevice builtin

SSLStaplingCache shmcb:/var/cache/httpd/stapling_cache(128000)
<VirtualHost *:80>
RewriteEngine On
RewriteCond %{HTTPS} off
RewriteRule (.*) https://host.tld:443%{REQUEST_URI}
</VirtualHost>

#ModPagespeedEnableFilters insert_ga
#ModPagespeedAnalyticsID <Analytics ID>

<VirtualHost _default_:443>
<If "%{HTTP_HOST} != 'host.tld'">
Redirect "/" "https://host.tld"
</If>
<Files wp-config.php>
Order allow,deny
Deny from all
</Files>
DocumentRoot /var/www/html/wordpress
ErrorLog logs/ssl_error_log
TransferLog logs/ssl_access_log
LogLevel warn
SSLEngine on
SSLProtocol +TLSv1.2
SSLHonorCipherOrder on
SSLCipherSuite EECDH+ECDSA+AESGCM:EECDH+aRSA+AESGCM:EECDH+ECDSA+SHA384:EECDH+ECDSA+SHA256:EECDH+aRSA+SHA384:EECDH+aRSA+SHA256:HIGH:!MEDIUM:!aNULL:!MD5:!SEED:!IDEA
SSLCertificateFile /etc/pki/tls/certs/localhost.crt
SSLCertificateKeyFile /etc/pki/tls/private/localhost.key
SSLUseStapling on
Header always set Strict-Transport-Security "max-age=15638400;"

AddOutputFilterByType DEFLATE text/plain
AddOutputFilterByType DEFLATE text/html
AddOutputFilterByType DEFLATE text/xml
AddOutputFilterByType DEFLATE text/css
AddOutputFilterByType DEFLATE text/javascript
AddOutputFilterByType DEFLATE application/xml
AddOutputFilterByType DEFLATE application/xhtml+xml
AddOutputFilterByType DEFLATE application/rss+xml
AddOutputFilterByType DEFLATE application/javascript
AddOutputFilterByType DEFLATE application/x-javascript

<Directory "/var/www/html/wordpress">
RewriteEngine On
RewriteBase /

RewriteRule ^index\.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
</Directory>

<filesmatch ".svg$">
SetOutputFilter DEFLATE
</filesmatch>

ExpiresActive On
<filesMatch ".(svg|css|jpg|jpeg|png|gif|js|ico)$">
ExpiresDefault A604800
Header unset Cache-Control
Header unset Vary
</filesMatch>

</VirtualHost>

• Update settings with correct url.

sudo sed -i 's/host\.tld/<yourdomainhere>/g' /etc/httpd/conf.d/vhost.conf

• Restart Apache and start the WordPress Installation

sudo apachectl graceful

IPTABLES

• Change default input to drop, allow new and established ssh and web connections.

sudo /sbin/iptables -A INPUT -p tcp --dport 80 -m state --state  NEW -j ACCEPT
sudo /sbin/iptables -A INPUT -p tcp --dport 443 -m state --state  NEW -j ACCEPT
sudo /sbin/iptables -A INPUT -p tcp --dport 22 -m state --state  NEW -j ACCEPT
sudo /sbin/iptables -A INPUT -m state --state  ESTABLISHED -j ACCEPT
sudo /sbin/iptables -P INPUT DROP

WordPress Server Config

• NOTE: Lightsail/EC2 instances do not have static IPs by default. When creating the wordpress site it likes to create database entries based on the current url. You will want to make sure to provide a static IP to the instance before continuing.
• Grab latest WordPress files and place in web directory

wget https://wordpress.org/latest.tar.gz
mkdir build
cd build
tar -xf ../latest.tar.gz
sudo mv wordpress /var/www/html/wordpress

• Fix permissions

sudo find /var/www/html/wordpress/ -type d -exec chmod 755 {} \;
sudo find /var/www/html/wordpress/ -type f -exec chmod 644 {} \;
sudo find /var/www/html/wordpress/ -maxdepth 1 -type f -exec chmod 444 {} \;
sudo chown -R apache:apache /var/www/html/wordpress

WordPress Site Setup

• In your browser, open your site using the IP provided by Amazon. "https://xxx.xxx.xxx.xxx"
• Enter the database information from before and hit connect. If it fails, make sure you did not have any typos. You can always go back to the server and look at the MySQL history for what you entered.
• Apache does not have write access based on the permissions we set earlier, so you will need to create the /var/www/html/wordpress/wp-config.php file with the contents displayed in the browser.

sudo nano /var/www/html/wordpress/wp-config.php
Paste into file, then save/exit
sudo chmod 640 /var/www/html/wordpress/wp-config.php

• Enter site Title, admin username (admin), admin password, set email.
• When finished, log in with the credentials you just entered. Make sure to check for updates and that word press can install them.

Plugins

• Go to "Plugins" -> "Add New". Search for wordfence and install.

Wordfence Config

• It is important to have this plugin installed, especially if you have third parties managing things.

1. Go to "Firewall", "Manage WAF", and under "Web Application Firewall Status" change to "Enabled and Protecting.
2. Go to "Firewall", "Manage Brute Force Protection", and change the following
   1. Lock out after how many login failures : 5
   2. Lock out after how many forgot passwords attempts : 5
   3. Count failures over what time period : 30 minutes
   4. Amount of time a user is locked out : 30 minutes
   5. Immediately lock out invalid usernames : Check this box

Process that is just wrong

!!!!IGNORE THIS AS IT DOES NOT WORK!!!!! Bad practices and steps that simply do not work!!!!!!
These instructions follow my attempts for a generally "locked down" instance for running Word Press without losing sleep.

Version I am working with before updates
Linux ip-172-26-9-250 4.9.51-10.52.amzn1.x86_64 #1 SMP Fri Sep 29 01:16:19 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux

sudo yum -y update
sudo yum -y install libselinux libselinux-utils selinux-policy-minimum selinux-policy-mls selinux-policy-targeted policycoreutils fail2ban httpd24 mysql mysql-server php70 php70-mysqlnd mod24_ssl yum-cron
sudo ln -sf /usr/share/zoneinfo/America/New_York /etc/localtime
sudo sed -i 's/selinux=/selinux=1\ security=selinux\ enforcing=1/' /etc/grub.conf
sudo sed -i 's/selinux=/selinux=1\ security=selinux\ enforcing=1/' /boot/grub/menu.lst
sudo echo -e "ServerTokens Prod\nServerSignature Off" >> /etc/httpd/conf/httpd.conf
sudo rm -f /etc/httpd/conf.d/welcome.conf
sudo sed -i 's/expose_php\ =\ On/expose_php\ =\ off/; s/upload_max_filesize\ =\ 2M/upload_max_filesize\ =\ 128M/; s/post_max_size\ =\ 8M/post_max_size\ =\ 64M/; s/max_execution_time\ =\ 30/max_execuion_time\ =\ 60/' /etc/php.ini
sudo sed -i 's/update_cmd\ =\ default/update_cmd\ =\ security/' /etc/yum/yum-cron.conf

• Loosen PHP for the admins, this was done with previous sed command.

upload_max_filesize = 128M
post_max_size = 64M
memory_limit = 128M

sudo chkconfig fail2ban on
sudo chkconfig mysqld on
sudo chkconfig httpd on
sudo chkconfig yum-cron on
sudo touch /.autorelabel
sudo reboot

• After logging back in make sure services are started.

sudo service httpd status
sudo service mysqld status
sudo service fail2ban status

• Prepare MySQL for Word Press by creating a database.

sudo mysql_secure_installation
mysql -uroot -p

• Grab Word Press and install in the appropriate location

wget https://wordpress.org/latest.tar.gz
mkdir build
cd build
tar -xf ../latest.tar.gz
sudo mv wordpress /var/www/html/wordpress

• There are many ways to make this work, I prefer vhosts and sub directories. This will get us up and running with a self signed cert for initial configuration. Afterwards the cert should be updated.

sudo mv /etc/httpd/conf.d/ssl.conf ./
echo -e "LoadModule ssl_module modules/mod_ssl.so\nListen 443\nSSLPassPhraseDialog  builtin\nSSLSessionCache         shmcb:/var/cache/mod_ssl/scache(512000)\nSSLSessionCacheTimeout  300\nSSLMutex default\nSSLRandomSeed startup file:/dev/urandom  256\nSSLRandomSeed connect builtin\nSSLCryptoDevice builtin\n\n<VirtualHost *:80>\nRewriteEngine On\nRewriteCond %{HTTPS} off\nRewriteRule (.*) https://%{HTTP_HOST}:443%{REQUEST_URI}\n</VirtualHost>\n\n<VirtualHost _default_:443>\nDocumentRoot /var/www/html/wordpress\nErrorLog logs/ssl_error_log\nTransferLog logs/ssl_access_log\nLogLevel warn\nSSLEngine on\nSSLCertificateFile /etc/pki/tls/certs/localhost.crt\nSSLCertificateKeyFile /etc/pki/tls/private/localhost.key\n</VirtualHost>" > /etc/httpd/conf.d/vhost.conf

Since echo can not write to the destination file, here is the entry formatted for copy and past into a conf file

LoadModule ssl_module modules/mod_ssl.so
Listen 443
SSLPassPhraseDialog  builtin
SSLSessionCache         shmcb:/var/cache/mod_ssl/scache(512000)
SSLSessionCacheTimeout  300
SSLMutex default
SSLRandomSeed startup file:/dev/urandom  256
SSLRandomSeed connect builtin
SSLCryptoDevice builtin

<VirtualHost *:80>
RewriteEngine On
RewriteCond %{HTTPS} off
RewriteRule (.*) https://%{HTTP_HOST}:443%{REQUEST_URI}
</VirtualHost>

<VirtualHost _default_:443>
DocumentRoot /var/www/html/wordpress
ErrorLog logs/ssl_error_log
TransferLog logs/ssl_access_log
LogLevel warn
SSLEngine on
SSLCertificateFile /etc/pki/tls/certs/localhost.crt
SSLCertificateKeyFile /etc/pki/tls/private/localhost.key
</VirtualHost>

• Restart Apache

sudo apachectl graceful

• This needs to be updated: Allow the web server to write to the uploads directory for automatic updates. This first chown command shouldn't be needed, I will be doing further testing to ensure it can be removed.

sudo chown -R apache:apache /var/www/html/wordpress/*
sudo chcon -R -t httpd_sys_rw_content_t /var/www/html/wordpress/wp-content/uploads/*
sudo setsebool -P httpd_read_user_content on
sudo setsebool -P httpd_can_network_connect_db on

• Make sure that you use 172.0.0.1 for the database server, instead of localhost (it gets complicated otherwise)
• Add various contextual permissions (need to research this. Optionally you could enable httpd_unified, but this is not the best idea)

allow httpd_t etc_mail_t:dir { search getattr };
allow httpd_t http_port_t:tcp_socket name_connect;
allow httpd_t httpd_sys_content_t:dir write;
allow httpd_t initrc_t:unix_stream_socket connectto;
allow httpd_t user_home_t:file read;

• Fail2ban policy

sudo setsebool -P authlogin_nsswitch_use_ldap on
sudo semodule -i fail2ban.pp

• Make sure Amazon has the access it needs

sudo sudo setsebool -P authlogin_nsswitch_use_ldap on
sudo grep shutdown /var/log/audit/audit.log | audit2allow -M shutdown
sudo semodule -i shutdown.pp

• Reboot again just for the fun of it.
• Install Wordfence Security plugin. Modify settings to fit your needs.

SELinux Notes

• From before making any changes.

#============= httpd_t ==============
#!!!! This avc can be allowed using one of the these booleans:
#     httpd_can_network_relay, httpd_graceful_shutdown, allow_ypbind, httpd_can_network_connect

allow httpd_t http_port_t:tcp_socket name_connect;
#!!!! This avc can be allowed using one of the these booleans:
#     httpd_read_user_content, httpd_enable_homedirs

allow httpd_t user_home_t:dir getattr;

• sudo semanage fcontext -a -t httpd_sys_rw_content_t "/path(/.*)?"

https://www.centos.org/docs/5/html/5.2/Deployment_Guide/s2-swap-creating-file.html

https://www.modpagespeed.com/doc/filter-insert-ga

https://www.tecmint.com/hide-apache-web-server-version-information/

https://www.tecmint.com/hide-php-version-http-header/

https://premium.wpmudev.org/blog/increase-memory-limit/

https://codex.wordpress.org/Hardening_WordPress