CVE-2025-67976

Executive Summary

CVE-2025-67976 is a Missing Authorization vulnerability in the Watu Quiz WordPress plugin, affecting versions through 3.4.5. The flaw allows unauthenticated attackers to exploit incorrectly configured access control security levels, potentially leading to unauthorized data access or manipulation of quiz results. With a CVSS score of 6.5 (Medium), the vulnerability is remotely exploitable without authentication, but requires low attack complexity. No public proof-of-concept (PoC) or exploit code is currently available, and the vendor has not released a patch. This report provides a comprehensive technical analysis, detection rules, and mitigation strategies for DevSecOps and threat intelligence teams.

Supply Chain & Package Security

This vulnerability resides in the WordPress plugin ecosystem (Watu Quiz). As a third-party plugin, it introduces supply chain risk: users must rely on the vendor (Bob) for patches. No official patch exists, and the plugin is not distributed via npm, PyPI, Go, or Ruby registries. Organizations using this plugin should treat it as a high-risk component and consider temporary removal or strict access controls until a fix is available.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
• Base Score: 6.5 (Medium)
• Attack Vector: Network (AV:N) – Exploitable remotely.
• Attack Complexity: Low (AC:L) – No special conditions required.
• Privileges Required: None (PR:N) – No authentication needed.
• User Interaction: None (UI:N) – No victim action required.
• Scope: Unchanged (S:U) – Impact confined to the vulnerable component.
• Confidentiality Impact: Low (C:L) – Limited data exposure.
• Integrity Impact: Low (I:L) – Limited data modification.
• Availability Impact: None (A:N) – No denial of service.

Threat Level: Medium. The lack of authentication and low complexity make it attractive for automated scanning, but the limited impact (Low CIA) reduces urgency. However, in WordPress environments with sensitive quiz data (e.g., exam results, user PII), the risk escalates.

Deep Dive & Mechanics

The vulnerability stems from missing authorization checks in the Watu Quiz plugin’s AJAX handlers or REST endpoints. The plugin likely exposes functions that modify or retrieve quiz data without verifying user capabilities (e.g., wp_verify_nonce or current_user_can). Attackers can send crafted HTTP requests to these endpoints to:

• View quiz results of other users.
• Modify quiz questions or answers.
• Reset quiz progress.
• Escalate privileges if combined with other flaws.

Root Cause: The plugin fails to implement proper access control on server-side functions, relying on client-side checks that can be bypassed. This is a classic CWE-862 (Missing Authorization) issue.

Attack Flow:

1. Attacker identifies the vulnerable endpoint (e.g., /wp-admin/admin-ajax.php?action=watu_export_results).
2. Sends a POST/GET request with manipulated parameters (e.g., quiz_id).
3. Server processes the request without verifying the user’s role or nonce.
4. Attacker receives sensitive data or performs unauthorized actions.

Vulnerable vs. Patched Code

Since no patch is available, the following is a hypothetical comparison based on common fixes:

Vulnerable Code (watu.php, line ~150):

add_action('wp_ajax_nopriv_watu_export_results', 'watu_export_results');
function watu_export_results() {
    $quiz_id = intval($_REQUEST['quiz_id']);
    $results = $wpdb->get_results("SELECT * FROM {$wpdb->prefix}watu_results WHERE quiz_id = $quiz_id");
    echo json_encode($results);
    wp_die();
}

Patched Code (Hypothetical):

add_action('wp_ajax_watu_export_results', 'watu_export_results');
function watu_export_results() {
    if (!current_user_can('manage_options')) {
        wp_die('Unauthorized', 403);
    }
    $quiz_id = intval($_REQUEST['quiz_id']);
    $results = $wpdb->get_results("SELECT * FROM {$wpdb->prefix}watu_results WHERE quiz_id = $quiz_id");
    echo json_encode($results);
    wp_die();
}

Key Differences:

• Removed nopriv (no privilege) action hook.
• Added capability check (manage_options).
• Nonce verification should also be added.

Exploitation & Lab Setup

Red Team (Offensive)

Prerequisites:

• WordPress instance with Watu Quiz <= 3.4.5 installed.
• No authentication required.

Exploitation Steps:

1. Identify the vulnerable endpoint. Common Watu Quiz AJAX actions include:
   • watu_export_results
   • watu_import_questions
   • watu_take_quiz
2. Craft a request to export all quiz results:

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

3. If successful, the response contains JSON with quiz results (user IDs, scores, answers).

Advanced Exploitation:

• Use Burp Suite to fuzz for other unprotected actions.
• Combine with SQL injection if input sanitization is also missing.

Blue Team (Defensive)

Detection:

• Monitor for unusual AJAX requests to admin-ajax.php with action parameters starting with watu_.
• Alert on requests from unauthenticated users to watu_export_results or similar.

Honeypot:

• Deploy a fake Watu Quiz endpoint that logs attacker IPs and payloads.

Lab Setup:

# Install vulnerable plugin (replace with actual download if available)
docker run -d --name wp-vuln -p 8080:80 wordpress:latest
docker exec wp-vuln wp plugin install watu --version=3.4.5 --activate

Indicators of Compromise (IOCs)

• Network IOCs:

  • POST requests to /wp-admin/admin-ajax.php with action=watu_* parameters.
  • Unusual quiz_id values (e.g., sequential IDs, large numbers).
  • JSON responses containing user_id, score, answers fields.

• File IOCs:

  • Modified watu.php or other plugin files (check file integrity).
  • Unexpected entries in wp_watu_results database table.

• Log IOCs:

  • Apache/Nginx logs showing POST /wp-admin/admin-ajax.php with action=watu_export_results.
  • PHP error logs with warnings about missing nonce checks.

Detection Engineering

YARA Rule

rule CVE_2025_67976_Watu_Quiz_Exploit {
    meta:
        description = "Detects exploitation attempts against CVE-2025-67976 in Watu Quiz plugin"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-67976"
    strings:
        $ajax_action = "action=watu_" nocase
        $export = "export_results" nocase
        $import = "import_questions" nocase
        $take_quiz = "take_quiz" nocase
    condition:
        any of ($ajax_action) and any of ($export, $import, $take_quiz)
}

Sigma Rule

title: CVE-2025-67976 - Watu Quiz Missing Authorization Exploitation
id: 8a4b3c2d-1e5f-4a7b-9c8d-0e1f2a3b4c5d
status: experimental
description: Detects HTTP requests targeting vulnerable Watu Quiz AJAX endpoints without authentication
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
    service: access
detection:
    selection:
        cs-method: 'POST'
        cs-uri-query|contains: 'admin-ajax.php'
        cs-uri-query|contains: 'action=watu_'
    condition: selection
falsepositives:
    - Legitimate admin actions (if authenticated)
level: medium

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (
    msg:"CVE-2025-67976 - Watu Quiz Missing Authorization Exploit";
    flow:to_server,established;
    content:"POST"; http_method;
    content:"admin-ajax.php"; http_uri;
    content:"action=watu_"; http_client_body;
    classtype:attempted-recon;
    sid:1000001;
    rev:1;
    reference:cve,2025-67976;
)

Remediation & Mitigation

Immediate Actions:

1. Disable the plugin if not critical: wp plugin deactivate watu
2. Implement a Web Application Firewall (WAF) rule to block requests to admin-ajax.php with action=watu_* from unauthenticated users.
3. Restrict access to /wp-admin/admin-ajax.php via .htaccess:

   <Files "admin-ajax.php">
       Require ip 127.0.0.1
   </Files>
   

   (Note: This may break legitimate AJAX functionality; use with caution.)

Long-Term Fixes:

• Vendor Patch: Await official patch from Bob. Monitor the plugin’s update channel.
• Code Hardening: If you have access to the source, add capability checks and nonce verification to all AJAX handlers.
• Alternative Plugin: Migrate to a maintained quiz plugin (e.g., LearnDash, Quiz Master Next).

Detection & Monitoring:

• Deploy the Sigma/Suricata rules above.
• Enable WordPress audit logging (e.g., WP Activity Log plugin).
• Regularly scan for vulnerable plugin versions using tools like WPScan.

Valters IT