YARD is a popular documentation generator tool used by Ruby developers to create attractive, navigable and useful documentation for their projects. However, a critical security vulnerability (CVE-2024-27285) has been identified in the "frames.html" file within YARD's generated documentation. This vulnerability stems from the inadequate sanitization of user input in the JavaScript segment of the "frames.erb" template file, leading to potential Cross-Site Scripting (XSS) attacks. This vulnerability has been fixed in YARD .9.36. In this article, we take a close look at this issue, discuss some examples and provide links to the original references and exploit details.

1. Official YARD Github Repository (to emphasize the popularity of the project): https://github.com/lsegal/yard/
2. YARD Official Documentation: https://www.rubydoc.info/github/lsegal/yard/File/docs/GettingStarted.md
3. CVE Details with Exploit Description: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2024-27285

The Vulnerability

The "frames.html" file within the Yard Doc's generated documentation is vulnerable to Cross-Site Scripting (XSS) attacks due to inadequate sanitization of user input within the JavaScript segment of the "frames.erb" template file. This makes it possible for an attacker to inject malicious JavaScript code or HTML content into the documentation system through the vulnerable "frames.html" file.

Below is the code snippet from the vulnerable "frames.erb" template file

<script type="text/javascript">
  function toggle_element(hidden_div, link) {
    var elements = document.getElementsByClassName(hidden_div);
    var visible = link.innerHTML == "hide";
    for (var i = ; i < elements.length; ++i) {
      elements.item(i).style.display = (visible ? "none" : "");
    }
    link.innerHTML = (visible ? "show" : "hide");
  }
</script>

As you can see from the code snippet, the user input (link.innerHTML) is not adequately sanitized, making it susceptible to XSS attacks.

Exploit Details

An attacker could exploit this vulnerability by creating a specially crafted URL or sending a malicious request that includes a payload targeting the "frames.html" file. Once a user clicks on this URL or visits a website with the malicious request embedded, the attacker's payload would be executed as if it was part of the documentation content, potentially compromising the user's security and privacy.

For instance, an attacker could create a URL like the following that injects a malicious JavaScript payload:

http://example.com/documentation/frames.html?payload=<script>alert(document.cookie);</script>;

When a user visits this URL, the malicious payload (in this case, an alert with the user's cookies) would be executed, exposing sensitive information and potentially leading to further exploitation.

Mitigation and Fix

The vulnerability has been fixed in YARD version .9.36, where proper input sanitization and encoding are implemented in the "frames.erb" template file. It is recommended that users upgrade to this version or higher to protect against this vulnerability:

Conclusion

This vulnerability (CVE-2024-27285) in the "frames.html" file within YARD's generated documentation presents a significant security risk and must be addressed immediately. By ensuring you are using the fixed version (.9.36) or higher and applying proper input sanitization and encoding practices, you can protect your documentation from potential Cross-Site Scripting (XSS) attacks. Stay informed about security vulnerabilities within your development tools and dependencies to keep your projects secure and up-to-date.

Timeline

Published on: 02/28/2024 20:15:41 UTC
Last modified on: 03/06/2024 23:15:07 UTC