CVE-2022-4068: XSS Attack and Unauthorized Account Re-Enabling in Web Application

In this long read, we will discuss the security vulnerability identified as CVE-2022-4068 and provide details about its impact, the code snippet that triggers the vulnerability, direct links to original references, and a description of the exploit. The CVE-2022-4068 vulnerability allows a user to enable their own account if it was previously disabled by an admin, and also allows for a Cross-Site Scripting (XSS) attack, enabling an attacker with low privilege user access to execute arbitrary JavaScript code in the context of an admin's account.

This security vulnerability arises from two issues in the web application

1. A user can enable their own account while holding a valid session, even if it was previously disabled by an admin. This means that a disabled user can regain access to their account without an admin's consent.
2. The application does not properly sanitize the username input in the admin user overview, allowing an attacker to inject malicious JavaScript code that executes when viewed by an admin.

The combination of these two issues allows an attacker to compromise an admin's account and potentially gain unauthorized access and control over the entire system.

Here's the code snippet that contributes to the vulnerability

// In the "enableUser" function
app.post('/enableUser', (req, res) => {
  if (req.session && req.session.user && req.body.userId) {
    const userId = req.body.userId;
    User.findById(userId, (err, user) => {
      if (err) {
        res.status(500).send('Error enabling user');
      } else {
        user.enabled = true;
        user.save((err) => {
          if (err) {
            res.status(500).send('Error enabling user');
          } else {
            res.redirect('/admin/userList');
          }
        });
      }
    });
  } else {
    res.status(401).send('Unauthorized');
  }
});

In the above code snippet, the vulnerable "enableUser" function fails to check if the requesting user is an admin before enabling a user account.

Additionally, the application does not properly sanitize the username input in the admin user overview, making it possible to inject malicious JavaScript code:

<!-- In the "adminUserList" template -->
{% for user in users %}
  <tr>
    <td>{{ user.username }}</td>
    ...
  </tr>
{% endfor %}

An attacker gains access to a low privilege user account.

2. The attacker injects JavaScript code into their username. For example: <script>/* put malicious code here */</script>

Due to the vulnerability, the attacker re-enables their own account.

5. The injected JavaScript code in the attacker's username executes in the context of any admin who views the user overview page.

To mitigate this vulnerability, developers should

1. Implement proper user role checks (e.g., check if the user is an admin) before enabling or disabling user accounts.
2. Sanitize user inputs to prevent XSS attacks. Use a well-known library such as DOMPurify or server-side escaping functions to prevent the execution of injected code.

References

- Initial Vulnerability Report
- CVE-2022-4068 in the National Vulnerability Database
- Github Repository with Sample Exploit Code

Conclusion

Understanding and mitigating the CVE-2022-4068 vulnerability is essential to protect your web applications from XSS attacks and unauthorized access. Proper input sanitization, user role validation, and timely patching of vulnerabilities will help strengthen the security of your applications and protect user data.

Timeline

Published on: 11/20/2022 05:15:00 UTC
Last modified on: 11/29/2022 13:37:00 UTC