Ensure access to SSH public host key files is configured

보통레벨 1자동linux

설명

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.

점검 방법

감사 방식: 셸 명령

shell

alt0() { o=$(bash -c '#!/usr/bin/env bash
{
   l_ssh_group=""
   grep -Psiq -- '"'"'^\h*ID_LIKE="?([^#\n\r]+)?\bfedora\b'"'"' /etc/os-release 2>/dev/null && \
      grep -Psq -- '"'"'^ssh_keys\b'"'"' /etc/group 2>/dev/null && l_ssh_group="ssh_keys"
   while IFS= read -r l_key; do
      l_file="${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

예상 출력: compliant

조치 방법

조치 방식: 가이드 또는 인프라 패치

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}') }

속성

운영 체제: almalinux-9
태그: cis-convertedlinux
참고 자료: CIS AlmaLinux OS 9 Benchmark v3.0.0 - 5.1.4

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