Information
The default error and index.html pages for NGINX reveal that the server is NGINX. These default pages should be removed or modified so they do not advertise the underlying infrastructure of the server.
Rationale:
By gathering information about the server, attackers can target attacks against its known vulnerabilities. Removing pages that disclose the server runs NGINX helps reduce targeted attacks on the server.
Solution
Edit /usr/share/nginx/html/index.html and usr/share/nginx/html/50x.html and remove any lines that reference NGINX.