Ensure only strong Key Exchange algorithms are used

中等級 1自動化cos

說明

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

檢查方式

稽核方法: Shell 指令

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

預期輸出: compliant

修補方式

修補方法: 操作指南或基礎設施修補檔

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

屬性

作業系統: 不限
標籤: container-optimized-oscoscrypto
參考資料: CIS Google Container-Optimized OS Benchmark v1.2.0 - 5.1.15 Ensure only strong Key Exchange algorithms are used

檢查此主機

請在您有權稽核的機器上執行此指令。掃描為唯讀操作。

shell

tmaegis scan --target cos