Ensure access to SSH private host key files is configured

보통레벨 1자동linux

설명

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.

점검 방법

감사 방식: 셸 명령

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

예상 출력: compliant

조치 방법

조치 방식: 가이드 또는 인프라 패치

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…

속성

운영 체제: almalinux-9
태그: cis-convertedlinux
참고 자료: CIS AlmaLinux OS 9 Benchmark v3.0.0 - 5.1.3

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