CVE-2023-5417: Unauthorized Data Modification in Funnelforms Free WordPress Plugin

CVE-2023-5417 is a vulnerability worthy of attention for users of the Funnelforms Free plugin for WordPress. Released by the vendor, this security issue opens doors for attackers to modify certain parts of the website's content without having adequate permission. Given that we see increasing reliance on plugins for streamlined site management, it is crucial to understand the potential risks they carry and adopt necessary security measures to minimize the impact.

In this long read post, we will:

Discuss possible mitigation steps

CVE-2023-5417 Vulnerability Details

CVE-2023-5417 is an unauthorized data modification vulnerability found in the Funnelforms Free WordPress plugin. Affecting this plugin's versions up to (and including) 3.4, the vulnerability allows authenticated attackers with minimal permissions (subscriber privileges and above) to tweak the category assigned to a given post ID.

Official CVE details are available at the CVE List.

Problematic Code Snippet

The root cause of CVE-2023-5417 lies within the fnsf_update_category function, which lacks the necessary capability check. This absence means that it doesn't validate whether the user has the appropriate permissions to update the category associated with a post ID.

In Funnelforms Free WordPress plugin

/**
 * Funnelforms Free - Update Category
 */
function fnsf_update_category() {
    $post_id = (int) $_POST['post_id'];
    $category_id = (int) $_POST['category_id'];

    // Sanitize and validate Post ID and Category ID
    $post_id = filter_var($post_id, FILTER_SANITIZE_NUMBER_INT);
    $category_id = filter_var($category_id, FILTER_SANITIZE_NUMBER_INT);

    // Update the Funnelforms category
    update_post_meta($post_id, 'fnsf_category', $category_id);

    // Send a response to the client
    echo json_encode(array(
        'status'  => 'success',
        'message' => 'Funnelforms Category Updated Successfully!'
    ));
    wp_die();
}

add_action('wp_ajax_fnsf_update_category', 'fnsf_update_category');

Understanding the Exploit

The oversight in the fnsf_update_category function is the absence of a capability check, like current_user_can(), which would verify the permission levels of users attempting to modify the post ID's Funnelforms category. Given that the exploit targets authenticated attackers with subscriber-level permissions and above, an attacker could craft a malicious request aimed at modifying the categories of posts on the website.

By exploiting this vulnerability, attackers can potentially alter the organization of content on the affected website, impact user experience, and disrupt proper site functioning. Moreover, as attackers require only minimal permissions, there will be an increased risk, especially in websites with a larger pool of registered users.

Users of the Funnelforms Free plugin for WordPress are advised to implement the following measures

1. Update the Plugin: The first line of defense against CVE-2023-5417 is to ensure that the Funnelforms Free plugin is updated to the latest version or a version patched for this vulnerability. Keep an eye on the plugin's changelog or announcements from the vendor for updates.

2. Implement User Role Restrictions: Understand that this vulnerability targets users with subscriber-level permissions and above. Hence, it is wise to minimize the number of registered users and review user roles regularly. Remove unnecessary user accounts or downgrade their permissions whenever possible.

3. Introduce a Capability Check: Temporarily fix the vulnerability by introducing a capability check in the fnsf_update_category function. This verification will ensure that only users with adequate privileges can modify the category of posts.

function fnsf_update_category() {
    if (!current_user_can('manage_options')) {
        // Access Denied - User does not have sufficient privileges
        wp_die();
    }
    
    // Rest of the function
}

4. Monitor User Activity: Keep a vigilant eye on suspicious user activity, especially actions linked to updating categories. Implement a logging system to track changes made by users, which can be used to detect unauthorized modifications and aid in reverting such tampering.

Conclusion

CVE-2023-5417 is a vulnerability in the Funnelforms Free plugin for WordPress that allows users with minimal permissions to carry out unauthorized data modifications. By understanding the underlying code issues and adopting appropriate security tactics, website owners can protect their installations from potential data tampering. Remember that prevention is better than cure, especially in the context of cybersecurity.

Timeline

Published on: 11/22/2023 16:15:12 UTC
Last modified on: 11/27/2023 20:16:27 UTC