CVE-2024-54417

Executive Summary

CVE-2024-54417 is a Missing Authorization vulnerability in the WordPress plugin PixProof by Pixelgrade, affecting versions up to and including 2.0.1. This flaw allows unauthenticated attackers to access functionality that should be constrained by Access Control Lists (ACLs). The vulnerability has a CVSS score of 5.3 (Medium) and an EPSS score of 0.0%, indicating low exploitation likelihood at this time. No public proof-of-concept or patch is currently available. The core issue lies in improper permission checks on certain AJAX actions or REST endpoints, enabling unauthorized data access or function execution.

Supply Chain & Package Security

This vulnerability affects a WordPress plugin distributed via the official WordPress plugin repository. Users who installed PixProof from the WordPress dashboard or manually uploaded the plugin are at risk. Since no patch is available, the supply chain risk is elevated; users must rely on alternative mitigations such as disabling the plugin or implementing a Web Application Firewall (WAF) rule.

CVSS Breakdown & Threat Level

• Attack Vector (AV): Network (N) – Exploitable remotely.
• Attack Complexity (AC): Low (L) – No special conditions required.
• Privileges Required (PR): None (N) – No authentication needed.
• User Interaction (UI): None (N) – No user action required.
• Scope (S): Unchanged (U) – Exploit does not affect other components.
• Confidentiality (C): Low (L) – Limited data exposure.
• Integrity (I): None (N) – No data modification.
• Availability (A): None (N) – No denial of service.

Threat Level: Medium. While the CVSS score is moderate, the lack of authentication requirements and the potential for data leakage make this a significant concern for WordPress sites using PixProof.

Deep Dive & Mechanics

The vulnerability resides in the PixProof plugin’s handling of AJAX requests or REST API endpoints. The plugin fails to verify user capabilities (e.g., manage_options, edit_posts) before executing sensitive functions. An attacker can craft a direct HTTP request to a vulnerable endpoint, bypassing the intended access controls.

Root Cause: The plugin uses wp_ajax_ and wp_ajax_nopriv_ hooks without proper capability checks. For example, a function like pixproof_export_data() might be registered with add_action('wp_ajax_nopriv_pixproof_export', 'pixproof_export_data'), allowing unauthenticated access.

Attack Vector: An attacker sends a POST/GET request to /wp-admin/admin-ajax.php with the action parameter set to a vulnerable PixProof action. The server processes the request without verifying the user’s role.

Impact: Unauthorized access to plugin-specific data, such as proofing galleries, client information, or configuration settings. This could lead to information disclosure and further attacks.

Vulnerable vs. Patched Code

Since no patch is available, we can only infer the vulnerable pattern. A typical vulnerable code snippet might look like:

// Vulnerable: No capability check
add_action('wp_ajax_nopriv_pixproof_get_gallery', 'pixproof_get_gallery');
function pixproof_get_gallery() {
    $gallery_id = $_POST['gallery_id'];
    // Fetch and return gallery data
    echo json_encode(get_gallery_data($gallery_id));
    wp_die();
}

A patched version would include a capability check:

// Patched: Check user capability
add_action('wp_ajax_pixproof_get_gallery', 'pixproof_get_gallery');
add_action('wp_ajax_nopriv_pixproof_get_gallery', 'pixproof_get_gallery_denied');
function pixproof_get_gallery() {
    if (!current_user_can('edit_posts')) {
        wp_die('Unauthorized', 403);
    }
    $gallery_id = $_POST['gallery_id'];
    echo json_encode(get_gallery_data($gallery_id));
    wp_die();
}
function pixproof_get_gallery_denied() {
    wp_die('Unauthorized', 403);
}

Exploitation & Lab Setup

Red Team

1. Setup: Install WordPress with PixProof plugin version 2.0.1 on a local server (e.g., using Docker).
2. Recon: Identify vulnerable endpoints by examining the plugin source code for wp_ajax_nopriv_ hooks.
3. Exploit: Send a crafted request to admin-ajax.php:

   curl -X POST http://target/wp-admin/admin-ajax.php \
        -d "action=pixproof_get_gallery&gallery_id=1"
   

4. Verify: Check if the response contains sensitive data without authentication.

Blue Team

1. Detection: Monitor for unusual requests to admin-ajax.php with unknown or suspicious action parameters.
2. Mitigation: Implement a WAF rule to block requests to admin-ajax.php with action parameters starting with pixproof_ unless the user is authenticated.
3. Hardening: Disable the PixProof plugin until a patch is released. Alternatively, use a plugin like "Disable XML-RPC" to reduce attack surface.

Indicators of Compromise (IOCs)

• Network: HTTP requests to /wp-admin/admin-ajax.php with action=pixproof_* parameters from unauthenticated sources.
• Logs: WordPress debug log entries showing pixproof_ function calls without valid user sessions.
• File: Unexpected access to plugin files in /wp-content/plugins/pixproof/ by unauthenticated users.

Detection Engineering

YARA Rule

rule CVE_2024_54417_PixProof_Missing_Auth {
    meta:
        description = "Detects PixProof plugin files with missing authorization"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2024-54417"
    strings:
        $vuln_hook = /add_action\s*\(\s*['\"]wp_ajax_nopriv_pixproof_/
        $cap_check = /current_user_can\s*\(/
    condition:
        $vuln_hook and not $cap_check
}

Sigma Rule

title: CVE-2024-54417 PixProof Missing Authorization
id: 12345678-1234-1234-1234-123456789abc
status: experimental
description: Detects unauthenticated access to PixProof AJAX actions
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'POST'
        c-uri: '/wp-admin/admin-ajax.php'
        cs-uri-query: 'action=pixproof_*'
    condition: selection
falsepositives:
    - Legitimate admin actions (rare)
level: medium

Suricata Rule

alert http any any -> any any (msg:"CVE-2024-54417 PixProof Missing Authorization"; flow:to_server; content:"POST"; http_method; content:"/wp-admin/admin-ajax.php"; http_uri; content:"action=pixproof_"; http_client_body; classtype:attempted-recon; sid:1000001; rev:1;)

Remediation & Mitigation

1. Immediate: Disable the PixProof plugin until a patch is released.
2. Short-term: Implement a WAF rule to block unauthenticated requests to admin-ajax.php with action parameters starting with pixproof_.
3. Long-term: Monitor the Pixelgrade website for an official patch. Once available, update to the patched version immediately.
4. Alternative: If the plugin is critical, consider restricting access to admin-ajax.php via .htaccess or server configuration to authenticated users only.

Valters IT
DevSecOps & Cyber Threat Intelligence Expert