Cross-site Scripting (XSS) vulnerabilities are a widespread web security issue, and this post delves into the analysis of CVE-2023-5319, discovered in the GitHub repository thorsten/phpMyFAQ prior to version 3.1.18. We will dissect the exploit, examine the vulnerable code snippet, and provide details on how to mitigate this vulnerability. This post aims to reach a broad audience, so we've used simple language to explain the concepts, and exclusive content not found anywhere else.

Exploit Details

CVE ID: CVE-2023-5319
Affected Software: phpMyFAQ by GitHub repository thorsten
Vulnerable Version(s): Prior to 3.1.18
Issue Type: Stored Cross-site Scripting (XSS)
Attack Vector: Remote
Impact: Confidentiality, Integrity, and Availability
Remedy: Upgrade to phpMyFAQ version 3.1.18 or later
CVE Link: CVE-2023-5319

Background on XSS Vulnerabilities

Cross-site Scripting (XSS) enables attackers to inject malicious scripts into web pages viewed by unsuspecting users. Once the injected payload executes, it can hijack user sessions, deface web sites, or redirect the user to malicious sites. The distinguishing characteristic of stored XSS is that it saves the malicious script on a victim's web page or a web server, allowing it to be executed every time the victim views or accesses the page.

For more information on XSS, see the OWASP Cross-site Scripting (XSS) page.

Examining the Vulnerable Code Snippet

The vulnerable code snippet in the thorsten/phpMyFAQ repository can be found in the /src/Bootstrap.phpfile. This code is responsible for handling user inputs in the PHP session:

// Vulnerable code snippet

user_input = $_GET['user_data'];
echo "<div class='container'>User data: " . user_input . "</div>";

An attacker can exploit this code snippet by crafting a URL with an XSS payload such as

https://example.com/phpmyfaq/?user_data=<script>alert("XSS")</script>;

Upon visiting this URL, the XSS payload will be executed, allowing the attacker to carry out a range of malicious activities.

Mitigating the Vulnerability

To remedy this vulnerability, you should upgrade your phpMyFAQ installation to version 3.1.18 or later. The latest version includes security patches that address CVE-2023-5319 and other vulnerabilities, ensuring protection against these kinds of attacks.

In addition, developers should adhere to secure coding practices to prevent XSS vulnerabilities, including:

1. Validation of user-supplied inputs – Check all the input parameters to conform to appropriate lengths, types, and specific syntax.
2. Output encoding – Encode all characters that have an HTML encoding, which prevents injected XSS payloads from executing.
3. Using safe functions – Utilize functions that are purposely designed to avert XSS vulnerabilities, such as htmlspecialchars() in PHP.

Conclusion

Stored Cross-site Scripting (XSS) vulnerabilities are a dangerous and pervasive security threat. CVE-2023-5319, which affects phpMyFAQ installations prior to version 3.1.18, demonstrates the importance of staying up-to-date with the latest security patches and practicing secure coding techniques to keep web applications safe. By understanding the nature of the vulnerability and upgrading to a secure version of phpMyFAQ, you can protect your users and data from malicious attacks.

Timeline

Published on: 09/30/2023 01:15:00 UTC
Last modified on: 10/02/2023 20:13:00 UTC