Executive Summary

[{'type': 'paragraph', 'content': "The vulnerability exists in the Drag and Drop Multiple File Upload - Contact Form 7 WordPress plugin, specifically in versions up to and including 1.3.7.3. It is caused by insufficient validation of file types in the 'dnd_upload_cf7_upload' function, allowing unauthenticated attackers to upload arbitrary files to the server."}, {'type': 'paragraph', 'content': "This flaw can be exploited if the form includes a multiple file upload field that accepts all file types ('*'), enabling attackers to upload malicious files such as PHP scripts. This can potentially lead to remote code execution on the affected server."}, {'type': 'paragraph', 'content': 'The vulnerability was addressed in later versions (from 1.3.9.6 onwards) by improving file type validation, replacing insecure cookie usage with localStorage for session management, and enforcing stricter client-side and server-side checks to prevent bypassing blacklist filters.'}] [1, 3]

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Impact Analysis

This vulnerability can have severe impacts including unauthorized file uploads by attackers, which may lead to remote code execution on your server.

If exploited, attackers could upload malicious scripts that run on your server, potentially compromising your website, stealing data, defacing content, or using your server as a launchpad for further attacks.

The high CVSS score (8.1) reflects the critical nature of this vulnerability, indicating high confidentiality, integrity, and availability impacts.

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Compliance Impact

I don't know

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Detection Guidance

[{'type': 'paragraph', 'content': 'Detection of this vulnerability involves identifying if the affected WordPress plugin "Drag and Drop Multiple File Upload - Contact Form 7" is installed and running a vulnerable version (up to and including 1.3.7.3).'}, {'type': 'paragraph', 'content': 'You can check the plugin version on your WordPress site by running commands to list installed plugins and their versions.'}, {'type': 'list_item', 'content': 'Use WP-CLI to list plugins and versions: wp plugin list'}, {'type': 'list_item', 'content': 'Check the plugin directory for the version file or readme.txt to confirm the version.'}, {'type': 'paragraph', 'content': 'Additionally, monitoring for suspicious file uploads, especially PHP files or files with executable extensions uploaded via the contact form, can help detect exploitation attempts.'}, {'type': 'list_item', 'content': 'Search web server logs for POST requests to the upload endpoint or for unusual file uploads: grep -i "POST" /var/log/apache2/access.log | grep "wpcf7-dnd"'}, {'type': 'list_item', 'content': 'Scan the upload directories (e.g., wp-content/uploads/wpcf7-dnd/wpcf7-files) for unexpected PHP or executable files: find wp-content/uploads/wpcf7-dnd/wpcf7-files -type f \\( -name "*.php" -o -name "*.php5" -o -name "*.php7" -o -name "*.php8" \\)'}] [1, 3]

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Mitigation Strategies

[{'type': 'paragraph', 'content': 'The immediate mitigation step is to update the Drag and Drop Multiple File Upload - Contact Form 7 plugin to version 1.3.96 or later, where the vulnerability has been fixed.'}, {'type': 'paragraph', 'content': 'This update includes stricter client-side and server-side validation to prevent arbitrary PHP file uploads and replaces insecure cookie usage with localStorage for session management.'}, {'type': 'paragraph', 'content': "If updating immediately is not possible, consider disabling the multiple file upload feature or restricting accepted file types in the form configuration to prevent the use of the wildcard '*' which allows all file types."}, {'type': 'paragraph', 'content': 'Additionally, review and harden file upload directories by ensuring proper .htaccess rules are in place to block execution of uploaded files and disable directory listing.'}, {'type': 'paragraph', 'content': 'Monitor and clean any suspicious files in the upload directories and consider implementing additional web application firewall (WAF) rules to block malicious upload attempts.'}] [1, 3]

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