I used observatory.mozilla.org to analyze the website, and found that the Scan Summary rating was only F. So, based on the explanation on the website, I slightly modified the Web server settings, as follows:

Header set Strict-Transport-Security "max-age=31536000; includeSubDomains; preload"
Header set Content-Security-Policy "*"
Header set X-Content-Type-Options "nosniff"
Header set X-Frame-Options "SAMEORIGIN"
Header set X-XSS-Protection "1; mode=block"

Consequently, the rating rose to A-. If I were to add all externally called domains to the Content-Security-Policy, I should probably get an A, but testing that is too much trouble, so I’ll make do with this for now.

The Scan Summary result from TLS Observatory was also F. Using the Mozilla SSL Configuration Generator, I added some parameters:

SSLCipherSuite ECDHE-ECDSA-CHACHA20-POLY1305:ECDHE-RSA-CHACHA20-POLY1305:ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-CM-SHA256:ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384:DHE-RSA-AES128-GCM-SHA256:DHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-AES128-SHA256:ECDHE-RSA-AES128-SHA256:ECDHE-ECDSA-AES128-SHA:ECDHE-RSA-AES256-SHA384:ECDHE-RSA-AES128-SHA:ECDHE-ECDSA-AES256-SHA384:ECDHE-ECDSA-AES256-SHA:ECDHE-RSA-AES256-SHA:DHE-RSA-AES128-SHA256:DHE-RSA-AES128-SHA:DHE-RSA-AES256-SHA256:DHE-RSA-AES256-SHA:ECDHE-ECDSA-DES-CBC3-SHA:ECDHE-RSA-DES-CBC3-SHA:EDH-RSA-DES-CBC3-SHA:AES128-GCM-SHA256:AES256-GCM-SHA384:AES128-SHA256:AES256-SHA256:AES128-SHA:AES256-SHA:DES-CBC3-SHA:!DSS
#SSLProtocol             all -SSLv3 -TLSv1 -TLSv1.1
#SSLHonorCipherOrder     on
#SSLCompression          off
#SSLSessionTickets       off

But it didn’t get any better, I don’t know why?

I need to find some time to look into this further.