CVE-2022-42094: In-Depth Analysis of Stored XSS Vulnerability in Backdrop CMS 1.23.

A recently discovered vulnerability, CVE-2022-42094, identifies a stored cross-site scripting (XSS) exploit in Backdrop CMS version 1.23.. This vulnerability affects the 'Card' content type, allowing a malicious user to inject scripts that can potentially compromise the entire website. This article will provide a detailed analysis of this vulnerability, including an examination of the vulnerable code snippet, links to original references, and detailed information regarding the exploit.

The Vulnerability: Stored XSS in 'Card' Content Type

Backdrop CMS version 1.23. suffers from a stored XSS vulnerability within its 'Card' content type, which is primarily used to display images, text, and links on the website. The issue resides in the improper handling of user-supplied input, which subsequently leads to the injection of malicious scripts.

The vulnerable code snippet affecting the 'Card' content type can be found in the following file

modules/contrib/card/templates/card.html.twig

In this file, the {{ content }} variable is not properly sanitized before being displayed to users. The code snippet appears as follows:

<div class="card{{ classes ? ' ' ~ classes }}">
  {% if image %}
    <div class="card__image">
      {{ content.image }}
    </div>
  {% endif %}
  <div class="card__content">
    {{ content }}
  </div>
</div>

This code outputs the content variable without any filtering, allowing an attacker to store malicious scripts in the 'Card' content type, which then trigger when the page is viewed by any user.

Exploit Details

An attacker with the appropriate privileges can exploit this vulnerability by crafting a malicious input containing JavaScript code. This input is then stored within the 'Card' content type. Although it appears harmless on the surface, the stored script will be executed every time a user visits the page containing the card.

For example, an attacker could inject the following script

<script>alert('XSS');</script>

This script will display a simple alert box containing the text "XSS" whenever a user visits the affected page. However, the potential for more sophisticated and potentially damaging exploits is a real concern.

Mitigation and Recommendations

To remediate this vulnerability, it is recommended that Backdrop CMS users either upgrade to the latest version (if available) or apply a patch that fixes the stored XSS vulnerability within the 'Card' content type. Developer's should sanitize the {{ content }} variable by using functions like check_plain() or filter_xss().

In general, web developers and administrators should be aware of the dangers of XSS vulnerabilities and implement best practices to minimize the risk of attacks. This includes:

Sanitizing user inputs and validating them against strict rules

- Employing Content Security Policies (CSP) to restrict the sources and types of content allowed on the site

References

- CVE-2022-42094 in NVD
- Backdrop CMS official website
- GitHub Issue reporting the vulnerability

Conclusion

In conclusion, the CVE-2022-42094 vulnerability highlights the importance of properly handling user inputs in web applications. In this case, a stored XSS vulnerability in the 'Card' content type of Backdrop CMS 1.23. allowed attackers to inject malicious scripts, ultimately putting website users at risk. As a web developer or administrator, you should ensure that your applications are protected against such exploits by sanitizing user inputs and applying the latest security patches to your software.

Timeline

Published on: 11/22/2022 13:15:00 UTC
Last modified on: 11/23/2022 19:21:00 UTC