A recent vulnerability has been discovered in the Highlight Focus WordPress Plugin, which potentially allows high privilege users like administrators to carry out Stored Cross-Site Scripting (XSS) attacks in certain conditions, even when the unfiltered_html capability isn't granted (e.g., in a multisite setup). This issue has been assigned the CVE identifier CVE-2022-3462.

The Highlight Focus Plugin, with versions up to and including 1.1, lacks proper sanitization and escaping mechanisms for some of its settings, leading to this security loophole. In this post, we'll share more details about the exploit, provide a code snippet to better understand the issue, and discuss the importance of keeping your plugins updated to prevent such vulnerabilities.

Exploit Details

The vulnerability lies in the plugin's improper handling of certain settings, leading to the possibility of Stored XSS attacks. Stored XSS attacks allow malicious scripts to be persistently stored by injecting them into stored content. If executed by a high privilege user (such as an admin), this could cause significant harm to a multisite WordPress installation, potentially affecting all sites within the network.

To better understand the vulnerability, let's take a look at a code snippet from the plugin's core

// file: highlight-focus.php
function save_post( $post_id ) {
    if ( isset( $_POST['highlight_focus_nonce'] ) ) {
        $nonce = $_POST['highlight_focus_nonce'];
        if ( ! wp_verify_nonce( $nonce, 'highlight_focus_save' ) ) {
            return $post_id;
        }
        $value = $_POST['highlight_focus_value'];
        update_post_meta( $post_id, 'highlight_focus_value', $value );
    }
}

In the code snippet above, the save_post() function is called to save the post's metadata. It verifies the nonce, which is supposed to ensure that the request is coming from a valid source. However, with the lack of proper data sanitization and escaping in place, the $value variable containing the plugin's setting is directly saved without any checks, making it vulnerable to Stored XSS attacks.

The following represents a possible exploit payload

<script>alert('XSS');</script>

A high privilege user could inject this malicious script in the highlight_focus_value setting, compromising the site and potentially causing harm to other sites in the network.

Mitigation

To address this vulnerability, it is highly recommended to update the Highlight Focus WordPress Plugin to the latest version (if available) or use an alternative plugin with proper sanitization and escaping mechanisms.

Also, it's essential to follow best practices regarding user roles and capabilities. Administrators should restrict access to high privilege users and ensure only trusted individuals are granted permissions capable of affecting the entire site network.

For further information on this vulnerability, please refer to the following resources

1. CVE-2022-3462
2. WordPress Plugin Vulnerability Database (WPVDB) Entry

Conclusion

To sum up, it's vital to keep your WordPress Plugins updated and make sure they follow industry best practices, particularly when dealing with data sanitization and escaping mechanisms. By doing this, you can prevent security vulnerabilities like the Stored Cross-Site Scripting issue found in the Highlight Focus WordPress Plugin (CVE-2022-3462) and protect your site against potential threats.

Timeline

Published on: 11/07/2022 10:15:00 UTC
Last modified on: 11/09/2022 20:08:00 UTC