CVE-2024-0983

Executive Summary

CVE-2024-0983 is a medium-severity vulnerability affecting the ImageRecycle pdf & image compression plugin for WordPress (versions up to and including 3.1.13). The issue stems from a missing capability check in the enableOptimization function, allowing authenticated attackers with subscriber-level access or higher to enable image optimization without proper authorization. This unauthorized modification of data can lead to resource abuse and potential performance degradation on the target WordPress site. The vulnerability has a CVSS score of 4.3 (Medium) and an EPSS score of 0.0%, indicating low exploitation likelihood at this time. No public proof-of-concept or exploit code is available, and the patch status remains unknown.

Supply Chain & Package Security

This vulnerability resides in a WordPress plugin ecosystem, not in a package manager like NPM or PyPI. However, the plugin is distributed via the official WordPress plugin repository, making it a supply chain risk for any WordPress site using ImageRecycle. Administrators should monitor for updates and verify plugin integrity.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
• Base Score: 4.3 (Medium)
• Attack Vector: Network (AV:N) – exploitable remotely.
• Attack Complexity: Low (AC:L) – no special conditions required.
• Privileges Required: Low (PR:L) – requires authenticated access (subscriber or above).
• User Interaction: None (UI:N) – no user action needed.
• Scope: Unchanged (S:U) – impact confined to the vulnerable component.
• Confidentiality Impact: None (C:N) – no data disclosure.
• Integrity Impact: Low (I:L) – unauthorized enabling of optimization.
• Availability Impact: None (A:N) – no direct denial of service.

Threat Level: Medium. While the impact is limited to enabling a feature, it could be chained with other vulnerabilities or used to exhaust server resources.

Deep Dive & Mechanics

The vulnerability exists in the enableOptimization function within the ImageRecycle plugin. This function is intended to be accessible only to administrators, but due to a missing capability check (CWE-862), any authenticated user with subscriber-level access or higher can call it. The function likely toggles a WordPress option or performs an AJAX action that enables image optimization for the site.

Root Cause: The plugin fails to use current_user_can() or similar WordPress capability checks before executing the optimization enable action. This allows low-privileged users to modify plugin settings.

Attack Scenario:

1. An attacker registers or compromises a subscriber account on the target WordPress site.
2. The attacker sends a crafted request to the vulnerable endpoint (e.g., /wp-admin/admin-ajax.php?action=enableOptimization).
3. The plugin enables image optimization without verifying the user's role.
4. This could lead to excessive resource consumption if optimization is triggered repeatedly or on large media files.

Vulnerable vs. Patched Code

Since no patch is available, we can only infer the vulnerable code pattern. The fix would involve adding a capability check.

Vulnerable Code (hypothetical):

function enableOptimization() {
    // Missing capability check
    update_option('imagerecycle_optimization_enabled', true);
    wp_die();
}
add_action('wp_ajax_enableOptimization', 'enableOptimization');

Patched Code (expected):

function enableOptimization() {
    if (!current_user_can('manage_options')) {
        wp_die('Unauthorized');
    }
    update_option('imagerecycle_optimization_enabled', true);
    wp_die();
}
add_action('wp_ajax_enableOptimization', 'enableOptimization');

Exploitation & Lab Setup

Red Team

Prerequisites:

• A WordPress site with ImageRecycle plugin <= 3.1.13.
• Valid subscriber credentials (e.g., username: attacker, password: password123).

Exploitation Steps:

1. Log in as the subscriber user.
2. Send a POST request to the WordPress AJAX endpoint:

curl -X POST 'http://target/wp-admin/admin-ajax.php' \
  -d 'action=enableOptimization' \
  --cookie 'wordpress_logged_in_xxx=attacker|...'

3. Verify the optimization is enabled by checking the plugin settings or observing behavior.

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

Blue Team

Detection:

• Monitor for AJAX requests to admin-ajax.php with action=enableOptimization from non-admin users.
• Alert on changes to the imagerecycle_optimization_enabled option.

Hunting:

• Search logs for enableOptimization action calls.
• Review user role assignments for unexpected subscriber accounts.

Indicators of Compromise (IOCs)

• Network: HTTP POST requests to /wp-admin/admin-ajax.php with parameter action=enableOptimization.
• File: No specific file changes; the plugin's option imagerecycle_optimization_enabled set to 1.
• Log: WordPress debug log entries showing enableOptimization function calls from low-privilege users.

Detection Engineering

YARA Rule

rule CVE_2024_0983_ImageRecycle_EnableOptimization {
    meta:
        description = "Detects missing capability check in ImageRecycle plugin enableOptimization function"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2024-0983"
    strings:
        $func = "enableOptimization" nocase
        $ajax = "wp_ajax_enableOptimization" nocase
        $cap = "current_user_can" nocase
    condition:
        $func and $ajax and not $cap
}

Sigma Rule

title: CVE-2024-0983 - ImageRecycle Plugin Unauthorized Optimization Enable
id: 8a7b3c2d-1e5f-4a6b-9c8d-0e1f2a3b4c5d
status: experimental
description: Detects attempts to enable image optimization via missing capability check
author: Valters IT
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: POST
        cs-uri-query|contains: 'action=enableOptimization'
    condition: selection
falsepositives:
    - Legitimate admin actions (rare)
level: medium

Suricata Rule

alert http any any -> any any (msg:"CVE-2024-0983 - ImageRecycle Plugin Unauthorized Optimization Enable"; flow:to_server,established; content:"POST"; http_method; content:"/wp-admin/admin-ajax.php"; http_uri; content:"action=enableOptimization"; http_client_body; classtype:attempted-admin; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable the plugin until a patch is released.
2. Restrict access to the AJAX endpoint using a Web Application Firewall (WAF) rule blocking action=enableOptimization for non-admin users.
3. Audit user accounts for unauthorized subscriber-level access.

Long-term Fix:

• Apply the vendor patch when available (currently unknown).
• Implement a custom capability check by modifying the plugin code (if allowed):

add_action('wp_ajax_enableOptimization', function() {
    if (!current_user_can('manage_options')) {
        wp_die('Unauthorized', 403);
    }
    // Original function logic
});

Workarounds:

• Use a security plugin like Wordfence to add virtual patching.
• Monitor for plugin updates via the WordPress dashboard.

Valters IT
Securing Digital Frontiers