CVE-2024-8858

Executive Summary

CVE-2024-8858 is a Stored Cross-Site Scripting (XSS) vulnerability in the Elementor Addons by Livemesh WordPress plugin, affecting all versions up to and including 8.5. The flaw resides in the piechart_settings parameter, where insufficient input sanitization and output escaping allow authenticated attackers with Contributor-level access or higher to inject arbitrary web scripts. These scripts execute whenever a user accesses a compromised page. The vulnerability is classified as a WordPress ecosystem issue, not related to Apache or Nginx. No public exploit code or proof-of-concept is currently available, and the patch status remains unknown. CVE-2024-47303 is likely a duplicate of this issue.

CVSS Breakdown & Threat Level

• CVSS Score: 6.4 (Medium)
• Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:L
• Attack Vector: Network
• Attack Complexity: Low
• Privileges Required: Low (Contributor-level)
• User Interaction: Required (victim must access the page)
• Scope: Changed (impact on other components)
• Confidentiality Impact: Low
• Integrity Impact: Low
• Availability Impact: Low

The threat level is medium due to the requirement for authenticated access and user interaction, but the potential for widespread exploitation in WordPress environments is significant.

Deep Dive & Mechanics

The vulnerability exists in the piechart_settings parameter of the Elementor Addons by Livemesh plugin. The plugin fails to properly sanitize user input and escape output when rendering pie chart settings. An attacker with Contributor-level access can inject malicious JavaScript into the parameter, which is then stored in the WordPress database. When a victim (including administrators) views the affected page, the injected script executes in their browser context, potentially leading to session hijacking, defacement, or data theft.

The root cause is a lack of input validation and output escaping in the plugin's rendering logic for pie chart elements. The piechart_settings parameter is likely processed by a shortcode or widget that directly outputs user-supplied data without proper sanitization.

Vulnerable vs. Patched Code

Since no patch is available, the vulnerable code is presumed to be in the plugin's rendering function for pie charts. A typical vulnerable pattern might look like:

// Vulnerable code (hypothetical)
function render_piechart($atts) {
    $settings = shortcode_atts(array('piechart_settings' => ''), $atts);
    echo '<div class="piechart" data-settings="' . $settings['piechart_settings'] . '">';
    // ...
}

A patched version would sanitize the input and escape the output:

// Patched code (hypothetical)
function render_piechart($atts) {
    $settings = shortcode_atts(array('piechart_settings' => ''), $atts);
    $safe_settings = sanitize_text_field($settings['piechart_settings']);
    echo '<div class="piechart" data-settings="' . esc_attr($safe_settings) . '">';
    // ...
}

Exploitation & Lab Setup

Red Team

1. Prerequisites: Obtain Contributor-level credentials on a WordPress site running the vulnerable plugin.
2. Craft Payload: Create a malicious JavaScript payload, e.g., <script>alert('XSS')</script>.
3. Inject: Edit a page or post and insert the payload into the piechart_settings parameter of the pie chart shortcode.
4. Trigger: Wait for an administrator or other user to view the page.

Example payload injection:

[piechart piechart_settings='<script>alert(document.cookie)</script>']

Blue Team

1. Monitor: Watch for unusual JavaScript execution in the browser console.
2. Audit: Review page/post content for unexpected script tags in shortcode parameters.
3. Harden: Restrict Contributor-level access and enforce Content Security Policy (CSP) headers.

Indicators of Compromise (IOCs)

• File: Suspicious entries in wp_posts table with post_content containing <script> tags in piechart_settings shortcode.
• Log: Web server logs showing requests to pages with piechart_settings parameter containing encoded JavaScript.
• Network: Outbound connections from compromised pages to attacker-controlled domains (if payload exfiltrates data).

Detection Engineering

YARA Rule

rule CVE_2024_8858_Stored_XSS {
    meta:
        description = "Detects stored XSS payloads in piechart_settings parameter"
        author = "Valters IT"
        date = "2024-10-01"
        reference = "CVE-2024-8858"
    strings:
        $payload1 = /piechart_settings\s*=\s*['\"][^'\"]*<script[^>]*>/
        $payload2 = /piechart_settings\s*=\s*['\"][^'\"]*on\w+\s*=/
    condition:
        any of them
}

Sigma Rule

title: CVE-2024-8858 Stored XSS Detection
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects potential stored XSS via piechart_settings parameter in WordPress
author: Valters IT
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'GET'
        cs-uri-query|contains: 'piechart_settings'
        cs-uri-query|re: '(<script|on\w+=)'
    condition: selection
falsepositives:
    - Legitimate use of JavaScript in shortcode parameters (rare)
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2024-8858 Stored XSS Attempt"; flow:to_server,established; content:"piechart_settings"; http_uri; pcre:"/(<script|on\w+=)/i"; classtype:web-application-attack; sid:1000001; rev:1;)

Remediation & Mitigation

1. Immediate: Disable the Elementor Addons by Livemesh plugin until a patch is released.
2. Short-term: Restrict Contributor-level access to trusted users only.
3. Long-term: Apply input sanitization (e.g., sanitize_text_field()) and output escaping (e.g., esc_attr()) to all shortcode parameters.
4. Monitor: Use the provided detection rules to identify exploitation attempts.

Valters IT
Senior DevSecOps & Cyber Threat Intelligence Expert