CVE-2022-38057

Executive Summary

CVE-2022-38057 is a Missing Authorization vulnerability in the ThemeHunk Advance WordPress Search Plugin (versions up to and including 1.2.1). This flaw allows unauthenticated attackers to bypass authorization checks and potentially access or modify sensitive data within the WordPress installation. The vulnerability is classified as a WordPress ecosystem issue, specifically affecting the plugin's AJAX handlers and REST endpoints that fail to properly verify user capabilities. With a CVSS score of 6.5 (Medium), the risk is elevated due to the lack of required privileges and the potential for data exposure or manipulation. No public proof-of-concept (PoC) or exploit code has been released, and the vendor has not provided a patch, leaving all installations of the plugin vulnerable.

Supply Chain & Package Security

This vulnerability affects a WordPress plugin distributed through the official WordPress plugin repository. Since the plugin is not an NPM, PyPI, Go, or Ruby package, supply chain risks are limited to the plugin's update mechanism and the integrity of the WordPress plugin directory. Users should verify the plugin's source and consider removing it if no patch is available.

CVSS Breakdown & Threat Level

• Attack Vector (AV): Network (N) – Exploitable remotely.
• Attack Complexity (AC): Low (L) – No special conditions required.
• Privileges Required (PR): None (N) – No authentication needed.
• User Interaction (UI): None (N) – No user action required.
• Scope (S): Unchanged (U) – Impact confined to the vulnerable component.
• Confidentiality (C): Low (L) – Limited data exposure.
• Integrity (I): Low (L) – Limited data modification.
• Availability (A): None (N) – No impact on availability.

Threat Level: Medium. The vulnerability is easy to exploit but has limited impact on confidentiality and integrity.

Deep Dive & Mechanics

The ThemeHunk Advance WordPress Search Plugin provides enhanced search functionality for WordPress sites. The vulnerability resides in the plugin's AJAX handlers and REST API endpoints that are intended for administrative or privileged users. Due to missing authorization checks (CWE-862), these endpoints can be invoked by any unauthenticated visitor.

Root Cause: The plugin registers AJAX actions (e.g., wp_ajax_advance_search_save_settings, wp_ajax_nopriv_advance_search_save_settings) without verifying the user's capabilities. The nopriv variant is particularly dangerous as it allows unauthenticated access. Similarly, REST API routes may lack permission callbacks.

Attack Vector: An attacker can craft HTTP requests to these endpoints, bypassing authentication. For example, sending a POST request to /wp-admin/admin-ajax.php with the action parameter set to an unprotected function can trigger unauthorized operations.

Impact: Successful exploitation could allow an attacker to:

• Modify plugin settings (e.g., search parameters, display options).
• Access search logs or cached data.
• Potentially escalate privileges if combined with other vulnerabilities.

Vulnerable vs. Patched Code

Since no patch is available, the vulnerable code remains in all versions up to 1.2.1. The following example illustrates the missing authorization:

Vulnerable Code (PHP):

add_action('wp_ajax_advance_search_save_settings', 'advance_search_save_settings');
add_action('wp_ajax_nopriv_advance_search_save_settings', 'advance_search_save_settings');

function advance_search_save_settings() {
    // No capability check
    update_option('advance_search_settings', $_POST['settings']);
    wp_die();
}

Patched Code (Hypothetical):

add_action('wp_ajax_advance_search_save_settings', 'advance_search_save_settings');
// Remove the nopriv action to require authentication

function advance_search_save_settings() {
    if (!current_user_can('manage_options')) {
        wp_die('Unauthorized', 403);
    }
    update_option('advance_search_settings', $_POST['settings']);
    wp_die();
}

Exploitation & Lab Setup

Red Team

Prerequisites:

• A WordPress site with the vulnerable plugin installed (version <= 1.2.1).
• Network access to the target.

Exploitation Steps:

1. Identify the vulnerable endpoint by scanning for AJAX actions.
2. Craft a request to modify plugin settings:

   curl -X POST http://target/wp-admin/admin-ajax.php \
        -d "action=advance_search_save_settings&settings[search_engine]=google"
   

3. Verify the change by checking the plugin's behavior or database.

Note: No public exploit code is available; this is a conceptual demonstration.

Blue Team

Detection:

• Monitor for unusual AJAX requests to admin-ajax.php with actions related to the plugin.
• Look for requests from unauthenticated users to wp_ajax_nopriv_* actions.
• Check for unauthorized changes to plugin options in the database.

Hunting:

• Search logs for patterns like action=advance_search_* from non-admin IPs.
• Use the Sigma rule below to detect exploitation attempts.

Indicators of Compromise (IOCs)

• Network:
  • HTTP POST requests to /wp-admin/admin-ajax.php with action=advance_search_* parameters.
  • Unusual wp_ajax_nopriv_* action calls from unauthenticated sources.
• File System:
  • Modified plugin files in /wp-content/plugins/advance-wordpress-search/.
• Database:
  • Unexpected values in the wp_options table under advance_search_settings.

Detection Engineering

YARA Rule

rule CVE_2022_38057_WordPress_Plugin
{
    meta:
        description = "Detects vulnerable ThemeHunk Advance WordPress Search Plugin files"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2022-38057"
    strings:
        $vuln_func = "wp_ajax_nopriv_advance_search" nocase
        $vuln_action = "advance_search_save_settings" nocase
    condition:
        $vuln_func or $vuln_action
}

Sigma Rule

title: CVE-2022-38057 - Missing Authorization in ThemeHunk Advance WordPress Search
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects exploitation attempts against CVE-2022-38057
author: Valters IT
date: 2025/04/10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'POST'
        cs-uri-query|contains: 'admin-ajax.php'
        cs-uri-query|contains: 'action=advance_search_'
    condition: selection
falsepositives:
    - Legitimate admin actions (rare)
level: medium

Suricata Rule

alert http any any -> any any (msg:"CVE-2022-38057 - ThemeHunk Advance WordPress Search Exploit"; flow:to_server,established; content:"POST"; http_method; content:"admin-ajax.php"; http_uri; content:"action=advance_search_"; http_client_body; classtype:attempted-admin; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable the plugin if not essential: Deactivate and delete the advance-wordpress-search plugin from the WordPress admin panel.
2. Implement a Web Application Firewall (WAF) rule to block requests to admin-ajax.php with action=advance_search_* from unauthenticated users.
3. Monitor logs for exploitation attempts using the provided detection rules.

Long-Term Fix:

• Since no patch is available, consider replacing the plugin with an alternative that is actively maintained.
• If the plugin is critical, manually patch the code by adding capability checks (as shown in the patched code example) and removing nopriv actions.

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