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Apache HTTP Server

TMA-APACHE-7.12

Ensure Only Cipher Suites That Provide Forward Secrecy Are Enabled

LowLevel 2Automatedapache

Description

In cryptography, forward secrecy (FS), which is also known as perfect forward secrecy (PFS), is a feature of specific key exchange protocols that give assurance that your session keys will not be compromised even if the private key of the server is compromised. The effective SSLCipherSuite (last one at server level and in each virtual host) is expanded with the local openssl ciphers -v; every TLS 1.2-and-older suite must use ephemeral key exchange (Kx=ECDH or DH). Fails when no SSLCipherSuite is configured. Reads the main configuration (APACHE_CONF overrides; default /etc/apache2/apache2.conf, /etc/httpd/conf/httpd.conf or /usr/local/apache2/conf/httpd.conf) and every Include/IncludeOptional file. CIS marks this recommendation Manual; the automated check implements its audit procedure.

How it is checked

Audit method: Shell command

shell
c=${APACHE_CONF:-}; if [ -z "$c" ]; then for f in /etc/apache2/apache2.conf /etc/httpd/conf/httpd.conf /usr/local/apache2/conf/httpd.conf /etc/apache2/httpd.conf; do [ -f "$f" ] && { c=$f; break; }; done; fi; [ -r "$c" ] || exit 1; R=$(awk 'tolower($1)=="serverroot"{v=$2; gsub(/"/,"",v); print v; exit}' "$c"); [ -n "$R" ] || R=$(dirname "$c"); shopt -s nocasematch; inc(){ local p g l; [ ${#FUNCNAME[@]} -lt 16 ] || return 0; p=$1; case $p in /*) ;; *) p=$R/$p;; esac; [ -d "$p" ] && p="$p/*"; for g in $p; do [ -f "$g" ] || continue; while IFS= read -r l || [ -n "$l" ]; do if [[ $l =~ ^[[:space:]]*include(optional)?[[:space:]]+\"?([^\"[:space:]]+) ]]; then inc "${BASH_REMATCH[2]}"; else printf '%s\n' "$l"; fi; done < "$g"; done; }; cfg=$(inc "$c" | sed -e 's/^[[:space:]]*//' -e '/^#/d' -e '/^$/d'); shopt -u nocasematch; eff(){ printf '%s\n' "$cfg" | awk -v k="$1" '{l=tolower($0)} l~/^<virtualhost/{vh=1; next} l~/^<\/virtualhost>/{if(v!="") print v; v=""; vh=0; next} tolower($1)==tolower(k){if(vh) v=$0; else g=$0} END{if(g!="") print g}'; }; s=$(eff SSLCipherSuite | awk 'tolower($1)=="sslciphersuite"{v=(NF>=3 && ($2=="SSL"||$2=="TLSv1.3"))?$3:$2; if(NF>=3 && $2=="TLSv1.3") next; gsub(/"/,"",v); print v}'); [ -n "$s" ] || { echo noncompliant; exit 0; }; command -v openssl >/dev/null || exit 1; bad=0; while IFS= read -r v; do o=$(openssl ciphers -v "$v" 2>/dev/null) || { bad=1; continue; }; printf '%s\n' "$o" | awk '$2!="TLSv1.3" && $3!~/^Kx=(ECDH|DH)$/' | grep -q . && bad=1; done <<< "$s"; [ "$bad" = 0 ] && echo compliant || echo noncompliant
Expected output
compliant

How it is fixed

Fix method: Guidance or infrastructure patch

SSLCipherSuite EECDH:EDH:!NULL:!SSLv2:!RC4:!aNULL:!3DES:!IDEA (at server level and in each TLS virtual host). Then run apachectl configtest and reload Apache.

Properties

Operating systems
Any
Tags
apachetls
Reference
CIS Apache HTTP Server 2.4 Benchmark v2.4.0 - 7.12 Ensure Only Cipher Suites That Provide Forward Secrecy Are Enabled

Check this host

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

shell
tmaegis scan --target apache --level 2