CVE-2025-31584

Executive Summary

CVE-2025-31584 is a Missing Authorization vulnerability in the Elfsight Testimonials Slider WordPress plugin (versions <= 1.0.1). This flaw allows an authenticated attacker with low privileges (e.g., subscriber) to exploit incorrectly configured access control security levels, potentially leading to unauthorized modification or disclosure of testimonials data. The vulnerability is classified as CWE-862: Missing Authorization and carries a CVSS score of 5.4 (Medium). As of this report, no official patch has been released, and no public exploit code or proof-of-concept is available. The plugin is part of the WordPress ecosystem, and exploitation could impact sites using this component for customer testimonials.

Supply Chain & Package Security

This vulnerability affects a WordPress plugin distributed via the official WordPress plugin repository and third-party marketplaces. Since no patch is available, users are advised to:

• Monitor the plugin’s official page for updates.
• Consider disabling or removing the plugin if not critical.
• Implement virtual patching via Web Application Firewall (WAF) rules.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N
• Base Score: 5.4 (Medium)
• Attack Vector: Network (AV:N)
• Attack Complexity: Low (AC:L)
• Privileges Required: Low (PR:L) – attacker needs a valid WordPress user account (e.g., subscriber).
• User Interaction: None (UI:N)
• Scope: Unchanged (S:U)
• Confidentiality Impact: Low (C:L) – limited data exposure.
• Integrity Impact: Low (I:L) – limited data modification.
• Availability Impact: None (A:N)

Threat Level: Medium. Exploitation requires authentication but low privileges, making it accessible to many attackers. The lack of a patch increases risk for unmaintained sites.

Deep Dive & Mechanics

The vulnerability resides in the Elfsight Testimonials Slider plugin’s AJAX handlers or REST endpoints that fail to properly verify user capabilities before processing requests. Specifically, the plugin does not enforce authorization checks for actions such as creating, editing, deleting, or viewing testimonials. An authenticated attacker with minimal privileges (e.g., subscriber) can craft HTTP requests to manipulate testimonial data.

Root Cause: The plugin uses wp_ajax_ hooks without checking current_user_can() or similar capability checks. For example, a function like elfsight_testimonials_slider_save_testimonial() may be registered for all authenticated users, allowing any logged-in user to modify testimonials.

Attack Flow:

1. Attacker authenticates as a low-privilege user (e.g., subscriber).
2. Attacker sends a crafted POST request to /wp-admin/admin-ajax.php with action parameter elfsight_testimonials_slider_save_testimonial and malicious payload.
3. The plugin processes the request without verifying if the user has edit_posts or manage_options capability.
4. Attacker can add, edit, or delete testimonials, potentially injecting malicious content or defacing the site.

Vulnerable vs. Patched Code

Since no patch is available, we compare the vulnerable code pattern with a hypothetical secure implementation.

Vulnerable Code (elfsight-testimonials-slider.php):

add_action('wp_ajax_elfsight_testimonials_slider_save_testimonial', 'elfsight_testimonials_slider_save_testimonial');
function elfsight_testimonials_slider_save_testimonial() {
    // No capability check
    $testimonial_data = $_POST['testimonial'];
    // Process and save data
    update_option('elfsight_testimonials', $testimonial_data);
    wp_die();
}

Patched Code (Hypothetical):

add_action('wp_ajax_elfsight_testimonials_slider_save_testimonial', 'elfsight_testimonials_slider_save_testimonial');
function elfsight_testimonials_slider_save_testimonial() {
    // Check if user has required capability
    if (!current_user_can('edit_posts')) {
        wp_die('Unauthorized', 403);
    }
    // Verify nonce for CSRF protection
    if (!wp_verify_nonce($_POST['_wpnonce'], 'elfsight_testimonials_nonce')) {
        wp_die('Invalid nonce', 403);
    }
    $testimonial_data = sanitize_text_field($_POST['testimonial']);
    update_option('elfsight_testimonials', $testimonial_data);
    wp_die();
}

Exploitation & Lab Setup

Red Team

Prerequisites:

• WordPress site with Elfsight Testimonials Slider <= 1.0.1 installed and active.
• Valid low-privilege user account (e.g., subscriber).

Exploitation Steps:

1. Log in as the low-privilege user.
2. Obtain a valid WordPress nonce (if required) by inspecting the plugin’s admin page.
3. Send a crafted AJAX request using curl or a browser console:

curl -X POST http://target.com/wp-admin/admin-ajax.php \
  -d "action=elfsight_testimonials_slider_save_testimonial&testimonial[author]=Hacker&testimonial[content]=Injected+Content&_wpnonce=VALID_NONCE"

4. Verify the injected testimonial appears on the site’s frontend.

Note: No public exploit code exists; this is a conceptual demonstration.

Blue Team

Detection & Prevention:

• Monitor AJAX requests to admin-ajax.php for unusual actions related to elfsight_testimonials_slider.
• Implement WAF rules to block requests with suspicious payloads in testimonial parameters.
• Use WordPress security plugins (e.g., Wordfence) to enforce capability checks.
• Disable the plugin if not essential.

Indicators of Compromise (IOCs)

• File Modifications: Unexpected changes to wp_options table where elfsight_testimonials option is stored.
• Network Traffic: POST requests to /wp-admin/admin-ajax.php with action=elfsight_testimonials_slider_* from low-privilege user sessions.
• Log Entries: WordPress debug log entries showing unauthorized AJAX calls.
• Frontend Anomalies: Unusual or malicious testimonials appearing on the site.

Detection Engineering

YARA Rule

rule Detect_Elfsight_Testimonials_Slider_Missing_Auth {
    meta:
        description = "Detects missing authorization in Elfsight Testimonials Slider plugin"
        author = "Valters IT"
        date = "2025-04-01"
        cve = "CVE-2025-31584"
    strings:
        $ajax_hook = "wp_ajax_elfsight_testimonials_slider_" ascii wide nocase
        $no_cap_check = "current_user_can" ascii wide nocase
    condition:
        $ajax_hook and not $no_cap_check
}

Sigma Rule

title: Elfsight Testimonials Slider Missing Authorization Exploitation
id: 8a4b3c2d-1e5f-4a7b-9c8d-0e1f2a3b4c5d
status: experimental
description: Detects exploitation attempts of CVE-2025-31584 via AJAX requests
author: Valters IT
date: 2025-04-01
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: "POST"
        c-uri|contains: "/wp-admin/admin-ajax.php"
        cs-uri-query|contains: "action=elfsight_testimonials_slider_"
    condition: selection
falsepositives:
    - Legitimate admin actions
level: medium

Suricata Rule

alert http any any -> any any (msg:"CVE-2025-31584 Elfsight Testimonials Slider Missing Authorization Exploit"; flow:to_server,established; content:"POST"; http_method; content:"/wp-admin/admin-ajax.php"; http_uri; content:"action=elfsight_testimonials_slider_"; http_client_body; classtype:attempted-admin; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable the plugin if not critical for business operations.
2. Implement virtual patching using WAF rules to block AJAX requests with elfsight_testimonials_slider_ actions from non-admin users.
3. Restrict user roles – ensure only trusted users have accounts on the site.

Long-Term Fix:

• Monitor the Elfsight plugin page for an official patch.
• If the plugin is abandoned, consider migrating to an alternative testimonials plugin with active security maintenance.
• Apply the principle of least privilege to all WordPress user roles.

Valters IT Signature:

Valters IT Cyber Threat Intelligence
Report ID: VIT-CVE-2025-31584
Classification: TLP:AMBER
Analyst: Valters IT DevSecOps Team