Ensure Any Signing Keys using RSA Have a Length of 2048 or Greater

低レベル 2自動bind

説明

If one of the RSA digital signature algorithms is used, then then key length should be at least 2048 bits. The Elliptic Curve algorithms have sufficient key length without any additional options, and will provide for smaller signed DNS responses then the RSA algorithms. The audit requires the base64 Prime1 value of every RSA K*.private key under $BIND_HOME to be at least 172 characters (2048-bit key).

チェック方法

監査方法: シェルコマンド

shell

BH=''; for d in /var/named /etc/bind /var/cache/bind; do [ -d "$d" ] && BH="$BH $d"; done
[ -n "$BH" ] || { echo 'no BIND directory found'; exit 1; }
RUN=''; for d in /run/named /var/run/named; do [ -d "$d" ] && { RUN=$d; break; }; done
G='-group root'; U='-user root'; for a in named bind; do grep -q "^$a:" /etc/group 2>/dev/null && G="$G -o -group $a"; grep -q "^$a:" /etc/passwd 2>/dev/null && U="$U -o -user $a"; done
RT='^(/var/named(/chroot/var/named)?/(dynamic|slaves|data)|/var/named/chroot/(var/)?run/named|/var/named/chroot/var/log|/var/named/chroot/(var/)?tmp|/var/cache/bind|/run/named|/var/run/named)(/|$)'
keys=$(find $BH /etc/bind/keys -name 'K*.private' -type f 2>/dev/null | sort -u)
[ -n "$keys" ] || { echo compliant; exit 0; }
bad=$(for k in $keys; do awk '/^Prime1:/ && length($2) < 172 {print FILENAME ": Prime1 length " length($2)}' "$k"; done)
[ -z "$bad" ] && echo compliant || printf '%s\n' "$bad"

期待される出力: compliant

修正方法

修正方法: ガイダンスまたは IaC パッチ

To remediate a weak RSA key, perform the following: ; Generate a new key to replace the weak key using dnssec-keygen and one of the recommended algorithms and key lengths. Examples commands are shown below. # dnssec-keygen -a RSASHA256 -b 2048 example.com # dnssec-keygen -a ECDSAP384SHA384 cisecurity.org ; Implement a rollover period to phase out the weak key and replace it with the the newly generated key. ; Once the key is fully deleted from the active use, remove the file.

プロパティ

オペレーティングシステム: すべて
タグ: binddnsdnssec
参照: CIS ISC BIND DNS Server 9.11 Benchmark v1.0.0 - 8.3 Ensure Any Signing Keys using RSA Have a Length of 2048 or Greater

このホストをチェック

監査が許可されているマシンで実行してください。スキャンは読み取り専用です。

shell

tmaegis scan --target bind --level 2