CVE-2023-41661 - Stored Cross-Site Scripting (XSS) Vulnerability in PressPage Entertainment Inc. Smarty for WordPress Plugin (<= 3.1.35)

In today's modern, security-conscious world, every software is prone to vulnerabilities, and the same stands true for web applications. One such vulnerability that recently came to light is CVE-2023-41661. This article presents a comprehensive dive into an important security flaw affecting PressPage Entertainment Inc.'s Smarty for WordPress plugin, where versions up to and including 3.1.35 were found to be susceptible to Stored Cross-Site Scripting (XSS) attacks. Here, we'll break down the issue at its core, examine some code snippets, provide original references, and offer some exploit details.

Background on Smarty for WordPress Plugin

PressPage Entertainment Inc. developed the Smarty for WordPress plugin to facilitate web developers in the management of their WordPress websites utilizing the popular PHP template engine, Smarty (Link: http://www.smarty.net/). However, as widely used as this plugin is, a recent vulnerability discovery has put its users' website security at risk.

Stored Cross-Site Scripting (XSS) Vulnerability

Stored Cross-Site Scripting (XSS) is a type of security attack that permits an attacker to inject malicious code, generally JavaScript, into a vulnerable web application. When other users access the affected web page, the malicious code gets executed, potentially leading to unauthorized code execution and undesirable consequences.

In the case of CVE-2023-41661, the Smarty for WordPress plugin allows Authenticated Stored XSS attacks targeting admin or higher privileged users. This implies that attackers, including unauthorized users, can exploit this vulnerability to successfully execute malicious code injection.

The following code snippet demonstrates the vulnerability in the Smarty for WordPress plugin

function smarty_ajax_callback() {
    $params = $_POST['params'];
    $smarty_instance = new SmartyWP();
    $output = $smarty_instance->fetch('string:'.$params);
    echo $output;
    die();
}
add_action('wp_ajax_smarty_ajax', 'smarty_ajax_callback');

This code is part of the Smarty for WordPress plugin and exposes an AJAX callback function, 'smarty_ajax_callback'. Notice that the '$params' variable gets its value from the '$_POST['params']' input, which is unsanitized and unvalidated. Consequently, the unsanitized input can be used to craft a malicious payload, leading to Stored XSS attacks.

Exploit Details

To carry out a successful exploit, an attacker can manipulate the '_POST' request, incorporating a malicious payload. The unsuspecting admin or a user with higher privileges will then suffer the consequences of accessing a web page that now has the injected malicious code.

For example, an attacker may craft an HTTP POST request similar to the following

POST /wp-admin/admin-ajax.php HTTP/1.1
Content-Type: application/x-www-form-urlencoded
Cookie: YOUR-WORDPRESS-COOKIES-HERE
Host: TARGET-SITE-HERE

action=smarty_ajax&params=<script>alert(1)</script>

The script in the 'params' key-value pair triggers an alert popup. While this script only displays an alert message, more menacing scripts can lead to unpleasant outcomes like compromising the admin's account, stealing sensitive information, and allowing unauthorized access to the web application.

Original References and Reporting

Credit goes to the security researchers who first reported this vulnerability. The following links provide additional details about CVE-2023-41661:

1. The National Vulnerability Database link - https://nvd.nist.gov/vuln/detail/CVE-2023-41661
2. The Wordpress Vulnerability Database link - https://wpscan.com/vulnerability/102c3e21-b3ed-486a-8cf-8ac536c116c

Mitigation & Recommendations

It's highly recommended that users employing the Smarty for WordPress plugin in their web applications immediately update to the latest version (beyond 3.1.35) if the plugin's developers have issued a security update. In general:

Regularly update all plugins and software components.

2. Employ robust input validation and sanitization methods to handle user inputs, particularly in PHP code.
3. Train application users, especially those with higher privileges, to recognize potential security threats.

Conclusion

Security vulnerabilities like Stored Cross-Site Scripting (XSS) are widespread, and even the most popular plugins and software components might be susceptible. In the case of CVE-2023-41661, the vulnerability affected PressPage Entertainment Inc.'s Smarty for WordPress plugin, versions up to and including 3.1.35. By closely examining the code snippets, exploring the exploit details, and referring to the original reports, users of the Smarty for WordPress plugin can now better protect their web applications from potential harm.

Timeline

Published on: 09/29/2023 14:15:10 UTC
Last modified on: 10/02/2023 20:06:08 UTC