Ensure the IP Addresses for Listening for Requests Are Specified

LowLevel 2Automatedapache

Description

The Apache Listen directive specifies the IP addresses and port numbers the Apache web server will listen for requests. Rather than be unrestricted to listen on all IP addresses available to the system, the specific IP address or addresses intended should be explicitly specified. Specifically, a Listen directive with no IP address specified, or with an IP address of zeros should not be used. Every Listen directive must name a specific IP address (not just a port, *, 0.0.0.0 or [::]). 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.

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 '/^$/d'); shopt -u nocasematch; printf '%s\n' "$cfg" | awk 'tolower($1)=="listen"{n++; v=$2; if(v~/^[0-9]+$/ || v~/^\*:/ || v~/^0\.0\.0\.0:/ || v~/^\[::\]:/) bad=1} END{print (n>0&&!bad)?"compliant":"noncompliant"}'

Expected output: compliant

How it is fixed

Fix method: Guidance or infrastructure patch

Change each Listen to an explicit address, e.g. Listen 10.20.30.40:80. Then run apachectl configtest and reload Apache.

Properties

Operating systems: Any
Tags: apachenetwork
Reference: CIS Apache HTTP Server 2.4 Benchmark v2.4.0 - 5.15 Ensure the IP Addresses for Listening for Requests Are Specified

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