Ensure sshd KexAlgorithms is configured

AltaNível 1Automatizadafreebsd

Descrição

Key exchange is any cryptography method that exchanges cryptographic keys between two parties, allowing the 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. Audit: the effective `kexalgorithms` list from `sshd -T` must not contain any weak algorithm listed by CIS.

Como é verificado

Método de auditoria: Comando shell

shell

command -v sshd >/dev/null 2>&1 || exit 1; out=$(sshd -T 2>/dev/null) || exit 1; line=$(printf '%s\n' "$out" | grep -i '^kexalgorithms '); [ -n "$line" ] || exit 1; printf '%s\n' "$line" | grep -Eiq -- '(^|[ ,])(diffie-hellman-group1-sha1|diffie-hellman-group14-sha1|diffie-hellman-group-exchange-sha1)(,|$)' && echo "weak: $line" || echo compliant

Saída esperada: compliant

Como é corrigido

Método de correção: Orientação ou patch de infraestrutura

Edit the /etc/ssh/sshd_config file and add/modify the KexAlgorithms line to contain a comma-separated list of the site unapproved (weak) KexAlgorithms preceded with a - above any Include entries: Example: KexAlgorithms -diffie-hellman-group1-sha1,diffie-hellman-group14-sha1,diffie- hellman-group-exchange-sha1

Propriedades

Sistemas operacionais: Qualquer
Tags: freebsdssh
Referência: CIS FreeBSD 14 Benchmark v1.0.1 - 4.2.11 Ensure sshd KexAlgorithms is configured

Verificar este host

Execute isto em uma máquina que você tenha permissão para auditar. A varredura é somente leitura.

shell

tmaegis scan --target freebsd