Ensure the LimitRequestFieldsize Directive is Set to 8190 or Less

LowLevel 2Automatedapache

Description

The LimitRequestFieldSize limits the number of bytes that will be allowed in an HTTP request header. It is recommended that the LimitRequestFieldSize directive be set to the default value of 8190 or less. LimitRequestFieldSize must be set and every value must be 8190 or less. 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)=="limitrequestfieldsize"{n++; v=$2+0; if(!(v<=8190)) bad=1} END{print (n>0&&!bad)?"compliant":"noncompliant"}'

Expected output: compliant

How it is fixed

Fix method: Guidance or infrastructure patch

Set LimitRequestFieldSize 8190 (or lower). Then run apachectl configtest and reload Apache.

Properties

Operating systems: Any
Tags: apacherequest-limits
Reference: CIS Apache HTTP Server 2.4 Benchmark v2.4.0 - 10.3 Ensure the LimitRequestFieldsize Directive is Set to 8190 or Less

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