Fail2ban filter for WordPress

With the annoying brute force wordpress hack going round, one way to protect your site(s) would be to use fail2ban, with a configuration something like (which I’ve shamelessly lifted from http://blog.somsip.com/2011/12/protecting-apache-webservers-from-wordpress-admin-login-dictionary-attacks/ ).

The below seems to be working, and given it’s relative simplicity it’s obvious how you’d go about changing to protect other POST based scripts from brute force attacks.

As with all fail2ban rules, it’s not going to work if the attacker changes IP often (but from scanning the logs so far, it doesn’t seem to be the case that they are).

Obvious caveats :

  1. Users who can’t remember their password(s) will get blocked.
  2. It’s not going to protect you from a distributed attack (multiple IPs) very well
  3. You may want to perform other counter-measures (like putting Apache http authentication in for URLs matching /wp-login.php)

 

In /etc/fail2ban/jail.conf :

[apache-wp-login]
enabled = true
port = http,https
filter = apache-wp-login
logpath = /var/www/vhosts/*/statistics/logs/access_log
maxretry = 5
findtime = 120

And In /etc/fail2ban/filter.d/apache-wp-login.conf :

[Definition]
failregex = <HOST>.*] "POST /wp-login.php
ignoreregex =

Users of Bytemark’s Symbiosis may wish to use a config more like :

  1. In /etc/fail2ban/filter.d/apache-wp-login.conf : failregex = ^ .* “POST /wp-login.php HTTP/1.1″
  2. In /etc/fail2ban/jail.conf : logpath = /srv/*/public/logs/access.log

5 thoughts on “Fail2ban filter for WordPress”

  1. This works great. I spent the last few days troubleshooting why fail2ban had quit working and ended up reinstalling it.

    In the process I expanded the functionality of the program.

    This jail alone caught over 1430 attempts at brute forcing our WP login page.

    Thanks for the write up.

  2. I’ve been experimenting with Fail2Ban for blocking failed WP logins, and this method has a couple of drawbacks.

    1. the failregex succeeds for all POST’s to wp-login.php, so this will catch successful logins, as well as failed ones.

    2. the logpath should be set to also watch access_ssl_log , so that failed logins over https will also get caught

    Solutions (for Apache):
    Modify the filter failregex to something like this:
    failregex = .*] “POST /wp-login.php HTTP/.*” 200

    Apache will return a 200 response code for a failed login via POST, and a 302 for a successful one. So the above filter should only catch failed logins. Test carefully though.

    My server has Plesk 12, so the correct logpath would be:
    logpath = /var/www/vhosts/system/*/logs/access*_log

    This will watch access_log as well as access_ssl_log

    Earlier versions of Plesk may have the logs in a different location, so always check first.

    Hope that helps.

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