There are news reports of new Wordpress XML-PRC brute force attacks being seen in the wild. The SANS Internet Storm Center also has a Diary entry showing similar data. We have captured similar attacks in our web honeypots so we wanted to share more data with the community. Please reference earlier blog posts we have done related to Wordpress:
Thanks goes to my SpiderLabs Research colleague Robert Rowley for help in validating data for this blog post.
Here is the general format of accessing this XML-RPC component:
As you can see, it is expecting username and password parameters.
Here is the data captured on our ModSecurity honepot:
This request was sending the following credentials:
Since we do not have Wordpress installed on our honeypot, there was no real response to this XML-RPC request. If we do send this request to some demo sites we have with Wordpress, we can see different methods of response.
If you do not have XML-RPC installed or activated, then you would receive a response similar to the following:
If the XML-RPC component is activated, but the user sends incorrect credentials along with the wp.getUsersBlogs request, they would receive a response similar to the following:
If the client sends the correct credentials to the XML-RPC component, then they would receive and XML response similar to the following:
It is important to note that the use of the wp.getUsersBlogs is but one of many possible vectors here so implementing a dumb block of that specific XML-RPC call will not suffice. Pretty much all of the components listed in XML-RPC API documentation require a username/password.
There are many reports that list this as some type of scraper tool possibly related to a virus. We have added this User-Agent string to our OWASP ModSecurity CRS repo.
We have added rules to our commercial ModSecurity rules package that will identify these XML-RPC authentication errors in the response bodies and generate alerts.