[Plugin: NextGEN Gallery] Browse to Gallery directories / hack url to watermarked images

I can browse to https://mysite.com/wordpress/wp-content/gallery/ or copy the link of a gallery image and just walk into all my gallery directories and files. This defeats the purpose of having watermarks if someone can just hack the url and get access.

What is the workaround? I’ve tried every combination of Gallery > Options > “activate permalink” and “Create new URL friendly image slugs” and updating Settings/Permalinks and the image URLs are always the same. I’ve changed my WP permalink structures (I prefer the custom /%postname% but tried the default page-id one).

I’ve tried to add an .htaccess file with Options -Index to the root of wp_content/gallery to force the index.php to be used but it breaks all the gallery functionality.

I’m using NextGen Gallery 1.8.3. I’ve been searching for hours and can’t find a solution to this. Please advise.

Thanks very much. A lot of great features of this plug-in. Am I missing something obvious?

https://www.ads-software.com/extend/plugins/nextgen-gallery/