CVE-2024-3233

Executive Summary

CVE-2024-3233 is a medium-severity vulnerability affecting the Ivory Search – WordPress Search Plugin for WordPress. The flaw resides in the ajax_create_index() function, which lacks a proper capability check. This allows authenticated attackers with subscriber-level access or higher to trigger the creation of search indexes without authorization. While the direct impact is limited to unauthorized data modification (index creation), it can lead to performance degradation or denial of service if abused repeatedly. The vulnerability affects all versions up to and including 5.5.5. No public exploit code or patch details are currently available, but the risk is elevated due to the low privileges required for exploitation.

WordPress Ecosystem Context

This vulnerability is specific to the Ivory Search WordPress plugin. It does not affect the core WordPress software or server infrastructure like Apache or Nginx. The attack surface is limited to WordPress installations where the plugin is active and accessible to authenticated users.

CVSS Breakdown & Threat Level

• CVSS Score: 4.3 (Medium)
• Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
• Attack Vector: Network
• Attack Complexity: Low
• Privileges Required: Low (Subscriber-level)
• User Interaction: None
• Scope: Unchanged
• Confidentiality Impact: None
• Integrity Impact: Low (Unauthorized index creation)
• Availability Impact: None

Threat Level: Medium. The vulnerability requires authentication but only at the subscriber level, making it accessible to a wide range of users. The impact is limited to integrity (index creation), but repeated exploitation could degrade site performance.

Deep Dive & Mechanics

The vulnerability exists in the ajax_create_index() function of the Ivory Search plugin. This function is intended to be called by administrators to rebuild or create search indexes. However, the function does not verify that the requesting user has the necessary capabilities (e.g., manage_options or edit_posts). As a result, any authenticated user, including subscribers, can trigger index creation via an AJAX request.

Root Cause: Missing capability check (CWE-862) in the ajax_create_index() function. The function registers an AJAX action for both authenticated and unauthenticated users but fails to enforce authorization.

Attack Flow:

1. An attacker registers or compromises a subscriber-level account on the WordPress site.
2. The attacker sends a crafted AJAX request to the vulnerable endpoint (e.g., wp-admin/admin-ajax.php?action=ivory_search_create_index).
3. The server processes the request and triggers index creation, potentially causing resource exhaustion or performance issues.

Impact: While the attacker cannot directly read or modify sensitive data, they can cause the search index to be rebuilt repeatedly, leading to high CPU/memory usage and potential denial of service.

Vulnerable vs. Patched Code

The vulnerable code likely resembles:

add_action('wp_ajax_ivory_search_create_index', 'ajax_create_index');
function ajax_create_index() {
    // No capability check
    // Index creation logic
    wp_send_json_success();
}

A patched version would include a capability check:

add_action('wp_ajax_ivory_search_create_index', 'ajax_create_index');
function ajax_create_index() {
    if (!current_user_can('manage_options')) {
        wp_die('Unauthorized', 403);
    }
    // Index creation logic
    wp_send_json_success();
}

The patch ensures only users with manage_options capability (typically administrators) can trigger index creation.

Exploitation & Lab Setup

Red Team

Prerequisites:

• A WordPress site with Ivory Search plugin version <= 5.5.5.
• Valid subscriber-level credentials (e.g., username: attacker, password: password123).

Exploitation Steps:

1. Log in as the subscriber.
2. Obtain a nonce if required (check the plugin's AJAX handler).
3. Send a POST request to wp-admin/admin-ajax.php with the action parameter.

Example cURL command:

curl -X POST \
  -c cookies.txt -b cookies.txt \
  -d "action=ivory_search_create_index&_ajax_nonce=<nonce>" \
  http://target.com/wp-admin/admin-ajax.php

Note: No public exploit code is available. The above is a conceptual example.

Blue Team

Detection:

• Monitor AJAX requests to admin-ajax.php with action ivory_search_create_index from non-admin users.
• Look for repeated index creation requests from the same IP or user.

Hunting Query (Splunk):

index=web sourcetype=access_combined
| search uri="/wp-admin/admin-ajax.php" action=ivory_search_create_index
| where user_role != "administrator"
| stats count by src_ip, user

Prevention:

• Apply the principle of least privilege; ensure only administrators can trigger index creation.
• Use a Web Application Firewall (WAF) to block requests to admin-ajax.php with suspicious actions from low-privilege users.

Indicators of Compromise (IOCs)

• Network:

  • POST requests to /wp-admin/admin-ajax.php with parameter action=ivory_search_create_index.
  • Repeated requests from the same IP within a short time frame.

• Host:

  • High CPU or memory usage on the WordPress server.
  • Log entries in wp-content/debug.log showing index creation errors.

• File:

  • Modified or corrupted search index files in wp-content/uploads/ivory-search/.

Detection Engineering

YARA Rule

rule CVE_2024_3233_Ivory_Search_Index_Creation {
    meta:
        description = "Detects exploitation attempts of CVE-2024-3233 in Ivory Search plugin"
        author = "Valters IT"
        date = "2024-01-01"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2024-3233"
    strings:
        $ajax_action = "ivory_search_create_index"
        $ajax_url = "admin-ajax.php"
    condition:
        $ajax_action and $ajax_url
}

Sigma Rule

title: CVE-2024-3233 - Ivory Search Unauthorized Index Creation
id: 12345678-1234-1234-1234-123456789abc
status: experimental
description: Detects unauthorized index creation attempts via Ivory Search plugin
author: Valters IT
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-uri-query|contains: "action=ivory_search_create_index"
    condition: selection
falsepositives:
    - Legitimate admin actions
level: medium

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (
    msg:"CVE-2024-3233 - Ivory Search Unauthorized Index Creation Attempt";
    flow:to_server,established;
    content:"POST"; http_method;
    content:"/wp-admin/admin-ajax.php"; http_uri;
    content:"action=ivory_search_create_index"; http_client_body;
    classtype:attempted-admin;
    sid:1000001;
    rev:1;
)

Remediation & Mitigation

Immediate Actions:

1. Update the plugin: If a patched version becomes available, update to the latest version immediately.
2. Disable the plugin: If no patch is available, consider disabling the Ivory Search plugin until a fix is released.
3. Restrict user roles: Remove subscriber-level accounts that are not necessary. Use a plugin like "User Role Editor" to limit capabilities.

Long-term Measures:

• Implement a Web Application Firewall (WAF) with rules to block AJAX requests to admin-ajax.php with suspicious actions from non-admin users.
• Regularly audit WordPress user roles and remove unused accounts.
• Monitor plugin updates and apply security patches promptly.

Workaround:

• Add a custom capability check by hooking into the plugin's AJAX action:

add_action('wp_ajax_ivory_search_create_index', function() {
    if (!current_user_can('manage_options')) {
        wp_die('Unauthorized', 403);
    }
}, 1);

This code snippet can be added to the theme's functions.php file or a custom plugin to enforce authorization.

Valters IT
Securing Digital Frontiers