PHP Image Upload Security Checklist: Comprehensive Protection

To ensure the security of your PHP image upload script, implementing thorough security measures is crucial. Here is a comprehensive checklist to guide you:

1. Disable PHP Execution: Prevent PHP code from executing within the upload directory using a .htaccess file.
2. Filter for PHP in Filenames: Reject uploads with filenames containing "php."
3. Restrict File Extensions: Limit accepted file extensions to images (e.g., jpg, jpeg, gif, png).
4. Verify Image Type: Use getimagesize() to confirm that uploaded files are genuine image types.
5. Disallow Double File Extensions: Check for files with multiple slashes in their MIME type, indicating a potential attempt at uploading an image with a malicious script.
6. Rename File: Change the uploaded filename to prevent exploitation via predictable file names.
7. Upload to a Subdirectory: Store uploaded images in a subdirectory to prevent direct website access.

Additional Recommendations:

• **Use move_uploaded_file(): Assign uploaded files to the destination path using move_uploaded_file().
• GD (or Imagick) Processing: Re-render uploaded images using GD or Imagick to mitigate potential threats.
• Restrictive Upload Directory: Keep upload directories highly restricted to prevent exploitation.