Ensure Online Certificate Status Protocol (OCSP) stapling is enabled

MediumLevel 1Automatednginx

Description

OCSP stapling allows a server to efficiently deliver certificate revocation information to the client, improving performance and privacy. The server caches the OCSP response from the Certificate Authority (CA), eliminating the need for the client to make a separate connection. All four directives must be present: ssl_stapling on, ssl_stapling_verify on, ssl_trusted_certificate and resolver. Evaluated on the merged configuration printed by `nginx -T` (all included files; needs permission to read them). CIS marks this recommendation Manual; the automated check implements its audit procedure.

How it is checked

Audit method: Shell command

shell

out=$(nginx -T 2>/dev/null) || exit 1; printf '%s\n' "$out" | awk '{l=$0; o=""; q=""; for(i=1;i<=length(l);i++){c=substr(l,i,1); if(q!=""){o=o c; if(c==q) q=""; continue} if(c=="\""||c=="\047"){q=c; o=o c; continue} if(c=="#") break; if(c==";"||c=="{"){print o c; o=""; continue} if(c=="}"){if(o~/[^[:space:]]/) print o; print "}"; o=""; continue} o=o c} if(o~/[^[:space:]]/) print o}' | awk 'function a(i,  x){x=$i; sub(/;$/,"",x); gsub(/["\047]/,"",x); return x} function inb(n,  i){for(i=1;i<=sp;i++) if(st[i]==n) return 1; return 0} $1=="ssl_stapling" && a(2)=="on"{s=1} $1=="ssl_stapling_verify" && a(2)=="on"{v=1} $1=="ssl_trusted_certificate"{t=1} $1=="resolver"{r=1} {o=gsub(/\{/,"{"); c=gsub(/\}/,"}"); while(o-->0){sp++; b=$1; sub(/\{.*/,"",b); st[sp]=b} while(c-->0 && sp>0) sp--} END{print (s&&v&&t&&r)?"compliant":"noncompliant"}'

Expected output: compliant

How it is fixed

Fix method: Guidance or infrastructure patch

Add 'ssl_stapling on; ssl_stapling_verify on; ssl_trusted_certificate /etc/nginx/ssl/chain.pem; resolver <dns ip>;' to the HTTPS server blocks. Then run nginx -t and reload nginx.

Properties

Operating systems: Any
Tags: nginxtls
Reference: CIS NGINX Benchmark v3.0.0 - 4.1.7 Ensure Online Certificate Status Protocol (OCSP) stapling is enabled

Check this host

Run this on a machine you are allowed to audit. The scan is read-only.

shell

tmaegis scan --target nginx