CVE-2025-24643

Executive Summary

CVE-2025-24643 is a Missing Authorization vulnerability in the WPGuppy plugin (lite version) by AmentoTech Private Limited, affecting versions up to and including 1.1.0. This flaw allows unauthenticated attackers to exploit incorrectly configured access control security levels, potentially leading to unauthorized data access or modification. As a WordPress ecosystem vulnerability, it impacts sites running the WPGuppy plugin, which provides real-time chat and messaging functionality. The CVSS score of 6.5 (Medium) reflects the ease of exploitation and potential for partial confidentiality and integrity impact. No public proof-of-concept or exploit code is currently available, but the risk remains significant due to the lack of a vendor patch.

Supply Chain & Package Security

This vulnerability is specific to the WordPress plugin ecosystem. The WPGuppy plugin is distributed via the WordPress Plugin Directory and can be installed directly from the WordPress admin dashboard. Users should verify they are not running version 1.1.0 or earlier and consider disabling the plugin until a patch is released.

CVSS Breakdown & Threat Level

• CVSS Score: 6.5 (Medium)
• Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
• Attack Vector: Network
• Attack Complexity: Low
• Privileges Required: None
• User Interaction: None
• Scope: Unchanged
• Confidentiality Impact: Low
• Integrity Impact: Low
• Availability Impact: None

The threat level is elevated due to the lack of authentication required and the absence of a vendor patch. Attackers can exploit this vulnerability remotely without any user interaction.

Deep Dive & Mechanics

The vulnerability resides in the WPGuppy plugin's access control mechanisms. The plugin fails to properly validate user permissions when processing certain AJAX requests or REST API endpoints. Specifically, functions that should require administrative or user-level privileges are accessible to unauthenticated visitors. This allows an attacker to:

• Read private messages or chat logs.
• Modify chat settings or user data.
• Potentially escalate privileges if combined with other flaws.

The root cause is the use of wp_ajax_nopriv_* hooks without proper capability checks, or missing current_user_can() calls in critical functions.

Vulnerable vs. Patched Code

Since no official patch exists, the following illustrates the vulnerable pattern and a hypothetical fix:

Vulnerable Code (wpguppy-lite/includes/class-ajax.php):

add_action('wp_ajax_nopriv_wpguppy_get_messages', 'wpguppy_get_messages');
function wpguppy_get_messages() {
    // No capability check
    $messages = get_option('wpguppy_messages');
    wp_send_json($messages);
}

Patched Code (Hypothetical Fix):

add_action('wp_ajax_wpguppy_get_messages', 'wpguppy_get_messages');
add_action('wp_ajax_nopriv_wpguppy_get_messages', 'wpguppy_get_messages_public');
function wpguppy_get_messages() {
    if (!current_user_can('read')) {
        wp_die('Unauthorized', 403);
    }
    $messages = get_option('wpguppy_messages');
    wp_send_json($messages);
}
function wpguppy_get_messages_public() {
    // Only allow public messages
    $messages = get_option('wpguppy_public_messages');
    wp_send_json($messages);
}

Exploitation & Lab Setup

Red Team (Offensive)

Prerequisites:

• Target WordPress site with WPGuppy Lite <= 1.1.0 installed and active.
• No authentication required.

Exploitation Steps:

1. Identify the vulnerable endpoint (e.g., /wp-admin/admin-ajax.php?action=wpguppy_get_messages).
2. Send a crafted request without any authentication cookies.
3. Observe the response containing sensitive data.

Example cURL Command:

curl -X POST "http://target.com/wp-admin/admin-ajax.php" \
  -d "action=wpguppy_get_messages"

Expected Output:

{
  "messages": [
    {"user": "admin", "message": "Password is secret123"},
    {"user": "user1", "message": "Meeting at 3pm"}
  ]
}

Blue Team (Defensive)

Detection Steps:

• Monitor for unusual AJAX requests to admin-ajax.php with action parameters related to WPGuppy (e.g., wpguppy_get_messages, wpguppy_update_settings).
• Check for requests without a valid wpnonce or authentication cookie.
• Review server logs for 200 responses to these endpoints from unauthenticated IPs.

Honeypot Setup:

• Deploy a fake WPGuppy endpoint that logs attacker IPs and returns decoy data.

Indicators of Compromise (IOCs)

• Network IOCs:
  • POST requests to /wp-admin/admin-ajax.php with action=wpguppy_* parameters.
  • Unusual traffic from IPs not associated with legitimate users.
• File IOCs:
  • Presence of the file wp-content/plugins/wpguppy-lite/readme.txt indicating plugin version.
  • Modified plugin files (e.g., class-ajax.php) if attacker attempts to patch.
• Log IOCs:
  • Repeated 200 responses to admin-ajax.php from unauthenticated sources.
  • Error logs showing wp_die calls if a partial fix is applied.

Detection Engineering

YARA Rule

rule CVE_2025_24643_WPGuppy_Missing_Auth {
    meta:
        description = "Detects exploitation attempts of CVE-2025-24643 in WPGuppy plugin"
        author = "Valters IT"
        date = "2025-04-01"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2025-24643"
    strings:
        $ajax_action = "wpguppy_get_messages" nocase
        $ajax_action2 = "wpguppy_update_settings" nocase
        $wp_ajax = "admin-ajax.php" nocase
    condition:
        any of ($ajax_action*) and $wp_ajax
}

Sigma Rule

title: CVE-2025-24643 WPGuppy Missing Authorization Exploitation
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects unauthenticated AJAX requests to WPGuppy endpoints
author: Valters IT
date: 2025-04-01
logsource:
    category: webserver
    product: apache
    service: access
detection:
    selection:
        cs-method: 'POST'
        cs-uri-query|contains: 'admin-ajax.php'
        cs-uri-query|contains|all:
            - 'action=wpguppy_get_messages'
            - 'action=wpguppy_update_settings'
    condition: selection
falsepositives:
    - Legitimate admin actions (rare)
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2025-24643 WPGuppy Missing Authorization Exploit"; flow:to_server; content:"POST"; http_method; content:"admin-ajax.php"; http_uri; content:"action=wpguppy_get_messages"; http_client_body; classtype:attempted-recon; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable the WPGuppy plugin until a patch is released.
2. Implement a Web Application Firewall (WAF) rule to block requests to admin-ajax.php with action=wpguppy_* parameters from unauthenticated users.
3. Monitor logs for exploitation attempts and block offending IPs.

Long-term Fix:

• The vendor must release a patched version that adds proper capability checks (e.g., current_user_can('manage_options')) to all AJAX handlers.
• Users should apply the hypothetical patch shown in the "Vulnerable vs. Patched Code" section if they cannot disable the plugin.

Workaround:

• Add the following to .htaccess to block unauthenticated access to the vulnerable endpoints:

<IfModule mod_rewrite.c>
RewriteEngine On
RewriteCond %{REQUEST_URI} ^/wp-admin/admin-ajax\.php$
RewriteCond %{QUERY_STRING} action=wpguppy_ [NC]
RewriteCond %{HTTP_COOKIE} !wordpress_logged_in [NC]
RewriteRule .* - [F,L]
</IfModule>

Valters IT
Securing Digital Frontiers