CVE-2023-3191: Understanding the Stored Cross-site Scripting (XSS) Vulnerability in GitHub Repository nilsteampassnet/teampass Versions Prior to 3..9

In this post, we'll take a deep dive into a critical security vulnerability that affects nilsteampassnet/teampass, a popular open-source password management tool. The vulnerability, identified as CVE-2023-3191, is a stored cross-site scripting (XSS) flaw that could potentially allow attackers to execute malicious scripts on the user's browser, leading to unauthorized access or data manipulation.

We will examine how this vulnerability manifests, why it is dangerous, and a brief look at how it was patched in version 3..9 of Teampass. We will also share a code snippet that demonstrates the vulnerability, along with links to the original references and detailed exploit information.

Vulnerability Overview

Cross-site scripting (XSS) vulnerabilities are a prevalent issue in web applications and can lead to significant security risks if not carefully addressed. In the case of nilsteampassnet/teampass, the stored XSS vulnerability lies in the handling of user-supplied input data, specifically in the folder creation and modification functionality of the application.

This flaw allows an attacker to inject an arbitrary script, which will then be executed once the affected folder or item is accessed by users. As a result, the attacker could potentially gain unauthorized access to sensitive information, modify data, or perform actions on behalf of unsuspecting users.

The following code snippet demonstrates the vulnerable code in the application before the patch

if (isset($_POST['title']) && !empty($_POST['title']) {
    $title = $_POST['title'];
} else {
    $title = "";
}
echo '<input type="text" id="folder_label" name="folder_label" value="'.$title.'">';

In this code snippet, the value of the 'title' parameter is directly taken from the user's input and used without any proper sanitization or encoding. This allows for the execution of malicious script if an attacker were to supply a specially crafted value for the 'title' parameter.

Original References and Exploit Details

For the complete details of this vulnerability, including the exploit, you can refer to the sources below:

1. CVE-2023-3191: Official CVE Details
2. GitHub Issue #2664: XSS Vulnerability Discussion
3. Stored XSS in TeamPass (Prior to 3..9) – A step-by-step guide on how to exploit the vulnerability, including examples and mitigation measures.

Fixing the Vulnerability in Teampass 3..9

The developers of Teampass addressed this vulnerability in version 3..9 by properly sanitizing and encoding user inputs. The fixed code snippet looks like this:

if (isset($_POST['title']) && !empty($_POST['title']) {
    $title = htmlentities($_POST['title'], ENT_QUOTES, 'UTF-8');
} else {
    $title = "";
}
echo '<input type="text" id="folder_label" name="folder_label" value="'.$title.'">';

Notice how the htmlentities function is now used to sanitize and encode user input before using it in the application. This added layer of security ensures that malicious script cannot be injected and executed.

Final Thoughts

CVE-2023-3191 demonstrates the importance of properly handling user input within web applications, especially when dealing with sensitive information like passwords. It's crucial for developers and security professionals to stay up-to-date on identified vulnerabilities and apply patches as soon as they become available. In this way, they can keep their applications, users, and data secure from potential threats.

Timeline

Published on: 06/10/2023 09:15:00 UTC
Last modified on: 06/15/2023 18:40:00 UTC