linux-rhosts-hostsequiv-misconfig: Rhosts and Hosts.equiv Misconfiguration Check

id: linux-rhosts-hostsequiv-misconfig

info:
  name: Rhosts and Hosts.equiv Misconfiguration Check
  author: songyaeji
  severity: high
  description: |
    Assessed the presence and configuration of .rhosts and /etc/hosts.equiv files. Files with unsafe '+' entries, incorrect permissions, or improper ownership could have permitted unauthorized remote command execution via rlogin or rsh.
  reference:
    - https://isms.kisa.or.kr
    - https://linux.die.net/man/5/hosts.equiv
  tags: linux,local,audit,kisa,compliance

self-contained: true

code:
  - engine:
      - bash
    source: |
      check_hosts_equiv() {
          if [ -f /etc/hosts.equiv ]; then
              echo "[FOUND] /etc/hosts.equiv exists"
              ls -l /etc/hosts.equiv
              if grep -q '^\+' /etc/hosts.equiv; then
                  echo "[WARN] Unsafe '+' entry found in /etc/hosts.equiv"
              fi
              perms=$(stat -c "%a" /etc/hosts.equiv)
              owner=$(stat -c "%U" /etc/hosts.equiv)
              if [ "$perms" -gt 644 ] || [ "$owner" != "root" ]; then
                  echo "[WARN] /etc/hosts.equiv has improper permissions or ownership"
              fi
          fi
      }

      check_rhosts() {
          find /home /root -maxdepth 2 -name ".rhosts" 2>/dev/null | while read rhost; do
              echo "[FOUND] $rhost"
              ls -l "$rhost"
              if grep -q '^\+' "$rhost"; then
                  echo "[WARN] Unsafe '+' entry found in $rhost"
              fi
              perms=$(stat -c "%a" "$rhost")
              owner=$(stat -c "%U" "$rhost")
              if [ "$perms" -gt 600 ] || [ "$owner" != "root" ]; then
                  echo "[WARN] $rhost has improper permissions or ownership"
              fi
          done
      }

      check_hosts_equiv
      check_rhosts

    matchers:
      - type: word
        part: response
        words:
          - "/etc/hosts.equiv"
          - ".rhosts"
          - "[WARN]"
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