Automation Controller NGINX web servers must maintain the confidentiality of controlled information during transmission through the use of an approved TLS version.

Transport Layer Security (TLS) is a required transmission protocol for a web server hosting controlled information. The use of TLS provides confidentiality of data in transit between the web server and client. FIPS 140-2 approved TLS versions must be enabled and non-FIPS-approved SSL versions must be disabled.

NIST SP 800-52 defines the approved TLS versions for government applications.

As a system administrator (SA), for each Automation Controller NGINX web server, validate the TLS version configuration:

nginx -T 2>&1 | grep ssl_protocols | grep -E 'ssl_protocols\s+TLSv1.2;' || echo "FAILED"

If "FAILED" is displayed, this is a finding.

As an SA, identify the active NGINX configuration files: nginx -T 2>&1 | grep '# configuration file'

Edit the relevant configuration file. Replace or add the ssl_protocols line: ssl_protocols TLSv1.2;

Save the file and restart NGINX: sudo systemctl restart nginx