CVE-2024-1334

Executive Summary

CVE-2024-1334 is a Cross-Site Request Forgery (CSRF) vulnerability in the ImageRecycle pdf & image compression plugin for WordPress, affecting all versions up to and including 3.1.13. The vulnerability exists in the enableOptimization function due to missing or incorrect nonce validation. This allows an unauthenticated attacker to trick a site administrator into performing an action (e.g., clicking a link) that enables image optimization without the administrator's consent. The CVSS score is 4.3 (Medium), with a low attack complexity and no privileges required, but user interaction is required. No public exploit code or proof-of-concept is currently available, and the patch status is unknown.

Supply Chain & Package Security

This vulnerability affects a WordPress plugin distributed via the official WordPress plugin repository. Users should verify the integrity of the plugin file and ensure they are using a trusted source. No known supply chain compromise has been reported.

CVSS Breakdown & Threat Level

• CVSS Score: 4.3 (Medium)
• Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N
• Attack Vector: Network
• Attack Complexity: Low
• Privileges Required: None
• User Interaction: Required
• Scope: Unchanged
• Confidentiality Impact: None
• Integrity Impact: Low
• Availability Impact: None

The threat level is considered Medium due to the requirement for user interaction (tricking an admin). However, the impact is limited to enabling image optimization, which may lead to further exploitation if combined with other vulnerabilities.

Deep Dive & Mechanics

The vulnerability is located in the enableOptimization function within the ImageRecycle plugin. This function is responsible for toggling the image optimization feature. In vulnerable versions, the function does not properly validate a nonce (a security token used to prevent CSRF attacks). As a result, an attacker can craft a malicious link or form that, when clicked by an authenticated administrator, will send a request to the WordPress site to enable image optimization without the admin's knowledge.

The attack flow:

1. Attacker crafts a malicious URL or HTML form that targets the enableOptimization endpoint.
2. Attacker tricks an authenticated WordPress administrator into clicking the link or submitting the form (e.g., via phishing email or social engineering).
3. The administrator's browser sends the forged request to the vulnerable WordPress site.
4. The server processes the request and enables image optimization, potentially altering site behavior or performance.

Vulnerable vs. Patched Code

Vulnerable Code (<= 3.1.13):

function enableOptimization() {
    // Missing nonce check
    update_option('imagerecycle_enable_optimization', true);
    wp_send_json_success();
}

Patched Code (Hypothetical):

function enableOptimization() {
    if (!wp_verify_nonce($_REQUEST['_wpnonce'], 'imagerecycle_enable_optimization')) {
        wp_die('Security check failed.');
    }
    update_option('imagerecycle_enable_optimization', true);
    wp_send_json_success();
}

The patched version includes a nonce verification using wp_verify_nonce() to ensure the request originated from the legitimate admin interface.

Exploitation & Lab Setup

Red Team (Attacker)

Prerequisites:

• A WordPress site with ImageRecycle plugin version <= 3.1.13 installed and activated.
• An authenticated administrator user.

Exploitation Steps:

1. Identify the vulnerable endpoint: http://target.com/wp-admin/admin-ajax.php?action=enableOptimization
2. Craft a malicious HTML page that automatically submits a POST request to the endpoint:

   <html>
   <body>
   <form action="http://target.com/wp-admin/admin-ajax.php" method="POST">
       <input type="hidden" name="action" value="enableOptimization">
       <input type="submit" value="Click me">
   </form>
   <script>document.forms[0].submit();</script>
   </body>
   </html>
   

3. Host the HTML page on an attacker-controlled server.
4. Send a phishing email to the administrator with a link to the malicious page.
5. Once the admin visits the page, the request is sent, and image optimization is enabled.

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

Blue Team (Defender)

Detection:

• Monitor for unusual requests to /wp-admin/admin-ajax.php with action=enableOptimization from unexpected referrers.
• Check for missing nonce parameters in AJAX requests.
• Review server logs for CSRF-like patterns.

Prevention:

• Ensure the plugin is updated to the latest patched version (if available).
• Implement Web Application Firewall (WAF) rules to block requests to admin-ajax.php without proper nonce.
• Educate administrators about phishing attacks and the importance of verifying links.

Indicators of Compromise (IOCs)

• Network IOCs:
  • HTTP POST requests to /wp-admin/admin-ajax.php with parameter action=enableOptimization.
  • Referrer headers from external domains (phishing pages).
• File IOCs:
  • Modified wp_options table entry: imagerecycle_enable_optimization set to 1.
• Log IOCs:
  • Access logs showing requests to admin-ajax.php with action=enableOptimization from non-admin IPs.

Detection Engineering

YARA Rule

rule CVE_2024_1334_ImageRecycle_CSRF {
    meta:
        description = "Detects vulnerable ImageRecycle plugin files with missing nonce in enableOptimization"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2024-1334"
    strings:
        $func = "function enableOptimization" nocase
        $nonce = "wp_verify_nonce" nocase
    condition:
        $func and not $nonce
}

Sigma Rule

title: CVE-2024-1334 ImageRecycle CSRF Exploitation Attempt
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects attempts to exploit CSRF in ImageRecycle plugin by monitoring admin-ajax.php requests with action enableOptimization
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=enableOptimization'
    condition: selection
falsepositives:
    - Legitimate admin actions (if nonce is present)
level: medium

Suricata Rule

alert http any any -> $HOME_NET any (
    msg:"CVE-2024-1334 ImageRecycle CSRF Exploitation Attempt";
    flow:to_server,established;
    content:"POST";
    http_method;
    content:"/wp-admin/admin-ajax.php";
    http_uri;
    content:"action=enableOptimization";
    http_client_body;
    classtype:attempted-recon;
    sid:1000001;
    rev:1;
)

Remediation & Mitigation

1. Immediate Actions:

   • Disable the ImageRecycle plugin until a patch is available.
   • Implement a Web Application Firewall (WAF) rule to block requests to admin-ajax.php with action=enableOptimization without a valid nonce.
   • Educate administrators to avoid clicking suspicious links.

2. Long-term Fix:

   • Apply the official patch from the plugin vendor when released.
   • Update to the latest version of the plugin (if patched version > 3.1.13 becomes available).
   • Regularly audit WordPress plugins for CSRF vulnerabilities.

3. Workaround:

   • Add a custom nonce check via a WordPress plugin or code snippet:

     add_action('wp_ajax_enableOptimization', function() {
         if (!wp_verify_nonce($_REQUEST['_wpnonce'], 'imagerecycle_enable_optimization')) {
             wp_die('CSRF detected.');
         }
         // Original function code
     }, 1);
     

Valters IT