Category: wordpress

Protecting your wordpress from multiple posts on wp-login.php and XMLRPC Bruteforce

I recently added New Relic server monitoring APM to my server and I noticed something interesting. Look at the screenshot below all the purple in the graph just shows that someone is brute-forcing my login. It is burning my much needed resources for other apps on the box with multiple posts on wp-login.php

wordpress-wp-login-post-bruteforce-new-relic

I needed to ensure this was legit so I took a look at my server access log and sure enough, multple posts to wp-login.php. I also noticed that they were also hitting admin-ajax.php. So unlikely this is a legit search engine bot and why would I want a bot to hit the admin section anyway.

Screen Shot 2016-03-20 at 9.13.40 AM

wp-login-wordpress-access-log

I think admin-ajax.php is used for the wordpress API.

Came across this blog post that suggests using HTTP Basic Auth to protect from brute force attacks.

To summarise that if you are creating a new .htpasswd use the -c:

sudo htpasswd -c /etc/apache2/.htpasswd username

You will then type the password

Then in your virtualhost config:

<DirectoryMatch ^.*/wp-admin/>
    AuthType Basic
    AuthName "Restricted"
    AuthUserFile /etc/apache2/.htpasswd
    Require valid-user
</DirectoryMatch>

Remember valid-user is the actual text that must appear, as the usernames are in your .htpasswd file.

I have just implemented this, I will let you know of the results…

WordPress Multiple posts on wp-login.php Results:

wordpress-wp-loginphp-results

Introducing the XML-RPC Attack

I continued to monitor the site and realised that the site was getting a lot of POST data to /xmlrpc.php

Here is some of the data I found with newrelic:

xml-rpc-data-new-relic xml-rpc-attack-data-new-relic

Here is some data from the access log, you can get it with:


grep xmlrpc access.log

xml-rpc-attack-apache-log

Solving the Xmlrpc issue

There is a good link from digitalocean on protecting your wordpress from the xmlrpc attack.

Basically it says you should install Jetpack and that is what I did. I await the results….A strange thing is that fail2ban did not block the ip…I guess fail2ban is not setup to watch the access logs. There is a tutorial on that here but I’m skipping that if Jetpack works.

Results of the Xmlrpc issue

Now whenever there is a supposed xmlrpc attack, there seems to be a lot of querying to api.bruteforceprotect.com, which is what jetpack uses to check whether it really is a bruteforce attack. The problem is that the attacks now look to be happening more frequently. Will update in a few days…

xmlrpc-attacks-bow-checking-bruteforceprotect

Wasn’t really blocking multiple posts on wp-login.php

So it turns out I wasnt blocking wp-login.php as it was in the root of the wordpress directory. I was still getting issues from newrelic (see the purple below)…

wp-login-spammed-wordpress

So to fix this issue or multiple posts on wp-login I added basic authentication to that file as well:


<Files wp-login.php>
 AuthUserFile /etc/apache2/.htpasswd
 AuthName "Do it! do it. do it."
 AuthType Basic
 Require valid-user
</Files>