Ensure access to SSH private host key files is configured

MoyenneNiveau 1Automatiséelinux

Description

An SSH private key is one of two files used in SSH public key authentication. In this authentication method, the possession of the private key is proof of identity. Only a private key that corresponds to a public key will be able to authenticate successfully. The private keys need to be stored and handled carefully, and no copies of the private key should be distributed.

Méthode de vérification

Méthode d'audit: Commande shell

shell

alt0() { o=$(bash -c '#!/usr/bin/env bash
{
   l_ssh_group=""
   grep -Psiq -- '"'"'^\h*ID_LIKE="?([^#\n\r]+)?\bfedora\b'"'"' /etc/os-release 2>/dev/null && \
      grep -Psq -- '"'"'^ssh_keys\b'"'"' /etc/group 2>/dev/null && l_ssh_group="ssh_keys"
   while IFS= read -r l_file; do
      ssh-keygen -lf "$l_file" &>/dev/null || continue
      while IFS=: read -r l_mode l_owner l_group; do
         [ "$l_group" = "$l_ssh_group" ] && l_mask="0137" || l_mask="0177"
         if [ $(( l_mode & l_mask )) -gt 0 ] || [ "$l_owner" != "root" ] || \
            { [ "$l_group" != "$l_ssh_group" ] && [ "$l_group" != "root" ];
}; then
            printf '"'"'%s\n'"'"' "\"$l_file\": mode $l_mode owner $l_owner group $l_group"
         fi
      done < <(stat -Lc '"'"'%#a:%U:%G'"'"' "$l_file")
   done < <(sshd -T 2>/dev/null | awk '"'"'$1=="hostkey"{print $2}'"'"')
}' 2>&1); [ -z "$o" ] || { echo "step1: $o" | head -c 300; return 1; }; }; if alt0; then echo compliant; fi

Sortie attendue: compliant

Méthode de correction

Méthode de correction: Recommandation ou correctif d'infrastructure

Run the following script to set the owner and restrict permissions on each SSH private host key file from the running sshd configuration: #!/usr/bin/env bash { while IFS= read -r l_file; do ssh-keygen -lf "$l_file" &>/dev/null || continue chown root:root "$l_file" chmod u-x,go-rwx "$l_file" done < <(sshd -T 2>/dev/null | awk '$1=="hostkey"{print $2}') } • OR - Where host-based authentication requires the ssh_keys group to read the host keys, set group ownership to ssh_keys with mode 0640 or more restrictive instead: #!/usr/bin/env bash { while IFS= read -r l_file; do ssh-keygen -lf "$l_file" &>/dev/null || continue chown root:ssh_keys "$l_file" chmod u-x,g-wx,o-rwx "$l_file" done < <(sshd -T…

Propriétés

Systèmes d'exploitation: almalinux-9
Étiquettes: cis-convertedlinux
Référence: CIS AlmaLinux OS 9 Benchmark v3.0.0 - 5.1.3

Vérifier cet hôte

Exécutez cette commande sur une machine que vous êtes autorisé à auditer. L'analyse est en lecture seule.

shell

tmaegis scan --target linux