Ensure access to SSH public host key files is configured

MediaNivel 1Automatizadalinux

Descripción

An SSH public key is one of two files used in SSH public key authentication. In this authentication method, a public key is a key that can be used for verifying digital signatures generated using a corresponding private key. Only a public key that corresponds to a private key will be able to authenticate successfully.

Cómo se verifica

Método de auditoría: Comando de shell

shell

alt0() { o=$(bash -c '#!/usr/bin/env bash
{
   l_ssh_group=""
   grep -Psiq -- '"'"'^\h*ID_LIKE="?([^#\n\r]+)?\bfedora\b'"'"' /etc/os-release 2>/dev/null && \
      grep -Psq -- '"'"'^ssh_keys\b'"'"' /etc/group 2>/dev/null && l_ssh_group="ssh_keys"
   while IFS= read -r l_key; do
      l_file="${l_key}.pub"
      ssh-keygen -lf "$l_file" &>/dev/null || continue
      while IFS=: read -r l_mode l_owner l_group; do
         if [ $(( l_mode & 0133 )) -gt 0 ] || [ "$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

Salida esperada: compliant

Cómo se corrige

Método de corrección: Guía o parche de infraestructura

Run the following script to set the owner, group, and restrict permissions on each SSH public host key file from the running sshd configuration: #!/usr/bin/env bash { while IFS= read -r l_key; do l_file="${l_key}.pub" [ -e "$l_file" ] || continue chown root:root "$l_file" chmod u-x,go-wx "$l_file" done < <(sshd -T 2>/dev/null | awk '$1=="hostkey"{print $2}') }

Propiedades

Sistemas operativos: rocky-9
Etiquetas: cis-convertedlinux
Referencia: CIS Rocky Linux 9 Benchmark v3.0.0 - 5.1.4

Verificar este host

Ejecute esto en un equipo que tenga permiso para auditar. El escaneo es de solo lectura.

shell

tmaegis scan --target linux