TMA-COS-5.1.15

Ensure only strong Key Exchange algorithms are used

中レベル 1自動cos

説明

Key exchange is any method in cryptography by which cryptographic keys are exchanged between two parties, allowing use of a cryptographic algorithm. If the sender and receiver wish to exchange encrypted messages, each must be equipped to encrypt messages to be sent and decrypt messages received Key exchange methods that are considered weak should be removed. A key exchange method may be weak because too few bits are used, or the hashing algorithm is considered too weak. Using weak algorithms could expose connections to man-in-the- middle attacks

チェック方法

監査方法: シェルコマンド

shell

alt0() { command -v grep >/dev/null 2>&1 || { echo "step1: grep not installed"; return 1; }; command -v sshd >/dev/null 2>&1 || { echo "step1: sshd not installed"; return 1; }; o=$(bash -c 'sshd -T | grep kexalgorithms' 2>&1); printf '%s\n' "$o" | tr -s ' \t' '  ' | sed 's/^ //;s/ $//' | grep -Fxq -- 'Weak Key Exchange Algorithms:' || { echo step1: missing 'Weak Key Exchange Algorithms:'; return 1; }; printf '%s\n' "$o" | tr -s ' \t' '  ' | sed 's/^ //;s/ $//' | grep -Fxq -- diffie-hellman-group1-sha1 || { echo step1: missing diffie-hellman-group1-sha1; return 1; }; printf '%s\n' "$o" | tr -s ' \t' '  ' | sed 's/^ //;s/ $//' | grep -Fxq -- diffie-hellman-group14-sha1 || { echo step1: missing diffie-hellman-group14-sha1; return 1; }; printf '%s\n' "$o" | tr -s ' \t' '  ' | sed 's/^ //;s/ $//' | grep -Fxq -- diffie-hellman-group-exchange-sha1 || { echo step1: missing diffie-hellman-group-exchange-sha1; return 1; }; }; if alt0; then echo compliant; fi

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

Edit the /etc/ssh/sshd_config file add/modify the KexAlgorithms line to contain a comma separated list of the site approved key exchange algorithms Example: KexAlgorithms curve25519-sha256,curve25519-sha256@libssh.org,diffie-hellman- group14-sha256,diffie-hellman-group16-sha512,diffie-hellman-group18- sha512,ecdh-sha2-nistp521,ecdh-sha2-nistp384,ecdh-sha2-nistp256,diffie- hellman-group-exchange-sha256

プロパティ

オペレーティングシステム: すべて
タグ: container-optimized-oscoscrypto
参照: CIS Google Container-Optimized OS Benchmark v1.2.0 - 5.1.15 Ensure only strong Key Exchange algorithms are used

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 cos