In this long-read post, we will explore a recently discovered Cross-site Scripting (XSS) vulnerability in the popular content management system (CMS) DedeCMS. The vulnerability has been assigned the CVE identifier CVE-2023-40876 and affects DedeCMS versions up to and including 5.7.110. We will explain what the vulnerability is, provide code snippets to demonstrate the exploit, and offer links to the original references for those who want to learn more.
What is DedeCMS?
DedeCMS (http://www.dedecms.com/) is a widely-used content management system (CMS) that allows users to easily create and manage websites. It is written in PHP and uses MySQL as its backend database, making it a popular choice for web developers worldwide.
The vulnerability: XSS in freelist_add.php
DedeCMS versions up to and including 5.7.110 were found to contain a cross-site scripting (XSS) vulnerability in the /dede/freelist_add.php file via the title parameter. XSS is a type of web security vulnerability that allows attackers to inject malicious scripts into web pages viewed by other users, potentially leading to data theft or other security issues.
Here is a simple code snippet that demonstrates how the XSS vulnerability can be exploited
<a href="http://target_site.com/dede/freelist_add.php?title=<script>alert('XSS')</script>">Click me</a>
In this example, the attacker creates a hyperlink that points to the target site's /dede/freelist_add.php file and includes a malicious script (<script>alert('XSS')</script>) in the title parameter. When a user clicks on the link, the malicious script is executed, triggering an alert dialog with the text 'XSS'. This is just a simple example for demonstration purposes; a real attack could involve more dangerous scripts and data theft.
Exploit details
The XSS vulnerability in DedeCMS up to and including 5.7.110 is caused by a lack of proper input validation and output sanitization. The server does not filter out potentially dangerous characters or restrict the use of certain HTML elements, such as <script>. As a result, an attacker could craft a request containing malicious scripts and trick a user into executing them, leading to various security issues.
The vulnerability could be exploited in various ways, such as sending malicious links to users via email or instant messaging, or including them in forum posts or website comments. In some cases, the attacker could automate the process, crafting and sending exploit payloads on an ongoing basis.
To mitigate the risk posed by this vulnerability, users are advised to update their DedeCMS installations to version 5.7.111 or later. In addition, web developers should ensure that they implement proper input validation and output sanitization for all user-supplied data to protect against XSS and other types of web security vulnerabilities.
Original references
For those who want to delve deeper into this vulnerability, the following links provide access to the original references and research materials:
1. CVE-2023-40876 - National Vulnerability Database (NVD)
2. DedeCMS official website
3. OWASP - Cross-Site Scripting (XSS)
In conclusion, the XSS vulnerability in DedeCMS versions up to 5.7.110 poses a significant risk to users, as it could lead to data theft and other security issues. By updating to the latest version of DedeCMS and implementing proper input validation and output sanitization, web developers can help protect their websites and user data from this and other web security vulnerabilities.
Timeline
Published on: 08/24/2023 15:15:07 UTC
Last modified on: 08/25/2023 13:20:10 UTC