Exploiting The Wordpress Pingback.ping

Hey gays, In this article I will deep dive with u into a vulnerability that i found during my last penetration testing project so it's a Real-world scenario

This article provides a comprehensive analysis of the security implications surrounding WordPress pingback.ping method. Often overlooked, this feature can be exploited by attackers to conduct various malicious activities such as Distributed Denial of Service (DDoS) attacks, network reconnaissance, and unauthorized access attempts. The article delves into how the pingback.ping method works, the common vulnerabilities associated with it, and the steps attackers take to exploit these weaknesses.

Key Points:

Key Pionts

Understanding Pingback.ping :
Explanation of the WordPress pingback.ping feature, which is intended to notify other blogs when content is referenced, Detailed description of the xmlrpc.php file used by WordPress to facilitate this feature.

First, we need to understand what an xmlrpc.php file ?

XML-RPC (Remote Procedure Call) is a protocol that allows software applications running on different systems to communicate with each other over the internet. It uses XML to encode requests and responses and can be used to perform various remote operations, such as publishing blog posts, managing content, and retrieving data.

In WordPress, xmlrpc.php is the file responsible for handling XML-RPC requests. It acts as an intermediary between external systems and the WordPress installation, allowing remote clients to interact with the site’s functionalities. By default, xmlrpc.php is located in the root directory of your WordPress installation.

XML-RPC in WordPress provides several methods and functionalities that can be accessed remotely one of these methods is pingback.ping so what does this method do?

A pingback is a special type of comment created when you link to another blog post as long as the other blog accepts pingbacks. Think of a pingback as an automated comment. Here is an example:

Let’s say you write a post titled “Great Post” and publish it.
One of your readers, who also has a website, really liked your “Great Post” and wanted to write their own post and link back to “Great Post.”
You get notified when they place a link to “Great Post” on their website.
This notification is the “pingback.” The pingback tells you and other website visitors that someone put a link to your post on their website.

This notification displays a special type of comment linking to their post. Pingbacks appear mixed in with any other comments on the post:

The pingback will also be listed in your dashboard’s Comments area.

Am.. okay , That's mean to use pingback.ping method we need 2 prerequisites :

The xmlrpc.php file enabled on our site
A post on our site to monitor it with pingback

Real-world scenario :
This is a real-world scenario from my last pentest to show u how I exploit this vulnerability

Let's see our website

Okay we identify that our target is run a WordPress CMS, let's check if the xmlrpc.php file is enabled

Okay seems our file only accept the POST requests let's try it with burpsuite

Nice It works ! , okay now what we should do ?

we should see if the xmlrpc enable the pingback.ping method to use it let's see how to figure it out

First, we need to list all the methods on the xmlrpc.php file with craft this xml payload with The system.listMethods function

<?xml version="1.0" encoding="utf-8"?> 
<methodCall> 
<methodName>system.listMethods</methodName> 
<params></params> 
</methodCall>

Nice, our method is enabled so what is next?

we need a post on the target to trick the server, let's see if this exists

The easiest way to find posts on the WordPress site is to add ?p=<NUMBER>

Nice , now we have all the ammo for our arsenal let's test it

We will use the pingback.ping method with our webhook token to recive the ping packet let's see how to do it

<?xml version=”1.0″ encoding=”UTF-8″?>
<methodCall>
<methodName>pingback.ping</methodName>
<params>
<param>
<value><string>[Our_Webhook_Url]</string></value>
</param>
<param>
<value><string>[Any blog post URL]</string></value>
</param>
</params>
</methodCall>

We received a packet in our webhook , It worked !

Mitigation Strategies for WordPress Pingback.ping :
To protect your WordPress site from exploits targeting the pingback.ping method

implement the following mitigation strategies :

Disable XML-RPC

The most effective way to prevent pingback.ping exploits is to disable XML-RPC entirely if it's not required for your site. You can do this by adding the following code to your theme's functions.php file:

phpCopy codeadd_filter('xmlrpc_enabled', '__return_false');

Use a Security Plugin

Install a reputable security plugin like Wordfence or Sucuri, which offers options to disable XML-RPC and monitor for suspicious activity.

Block Pingback Requests

If you need XML-RPC for other functionalities, you can block just the pingback requests. Add the following code to your .htaccess file:

apacheCopy code<Files xmlrpc.php>
order deny,allow
deny from all
</Files>

Limit XML-RPC Access

Restrict access to xmlrpc.php to specific IP addresses that need it, thereby reducing the attack surface. Modify your .htaccess file:

apacheCopy code<Files xmlrpc.php>
order deny,allow
deny from all
allow from 123.123.123.123
</Files>

Monitor and Log Requests

Regularly monitor your server logs for unusual XML-RPC requests. Implement logging and alerting mechanisms to detect and respond to potential attacks promptly.