Add linpeas privilege escalation checks from: Case study: Backup leak → CI abuse → internal trust misconfigurations → escalati

linPEAS/builder/linpeas_parts/4_procs_crons_timers_srvcs_sockets/15_Rcommands_trust.sh

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+# Title: Processes & Cron & Services & Timers - Legacy r-commands and host-based trust
+# ID: PR_Rcommands_trust
+# Author: HT Bot
+# Last Update: 27-08-2025
+# Description: Detect legacy r-services (rsh/rlogin/rexec) exposure and dangerous host-based trust (.rhosts/hosts.equiv),
+#              which can allow passwordless root via hostname/DNS manipulation.
+# License: GNU GPL
+# Version: 1.0
+# Functions Used: print_2title, print_3title, print_info, echo_not_found
+# Global Variables:
+# Initial Functions:
+# Generated Global Variables: $rfile, $perms, $owner, $g, $o, $any_rhosts, $shown, $f, $p
+# Fat linpeas: 0
+# Small linpeas: 1
+
+if ! [ "$SEARCH_IN_FOLDER" ]; then
+  print_2title "Legacy r-commands (rsh/rlogin/rexec) and host-based trust"
+  print_info "https://book.hacktricks.wiki/en/linux-hardening/privilege-escalation/index.html#r-commands-and-rhosts"
+
+  echo ""
+  print_3title "Listening r-services (TCP 512-514)"
+  if command -v ss >/dev/null 2>&1; then
+    ss -ltnp 2>/dev/null | awk '$1 ~ /^LISTEN$/ && $4 ~ /:(512|513|514)$/ {print}' || echo_not_found "ss"
+  elif command -v netstat >/dev/null 2>&1; then
+    netstat -ltnp 2>/dev/null | awk '$6 ~ /LISTEN/ && $4 ~ /:(512|513|514)$/ {print}' || echo_not_found "netstat"
+  else
+    echo_not_found "ss|netstat"
+  fi
+
+  echo ""
+  print_3title "systemd units exposing r-services"
+  if command -v systemctl >/dev/null 2>&1; then
+    systemctl list-unit-files 2>/dev/null | grep -E '^(rlogin|rsh|rexec)\.(socket|service)\b' || echo_not_found "rlogin|rsh|rexec units"
+    systemctl list-sockets 2>/dev/null | grep -E '\b(rlogin|rsh|rexec)\.socket\b' || true
+  else
+    echo_not_found "systemctl"
+  fi
+
+  echo ""
+  print_3title "inetd/xinetd configuration for r-services"
+  if [ -f /etc/inetd.conf ]; then
+    grep -vE '^\s*#|^\s*$' /etc/inetd.conf 2>/dev/null | grep -Ei '\b(shell|login|exec|rsh|rlogin|rexec)\b' 2>/dev/null || echo "  No r-services found in /etc/inetd.conf"
+  else
+    echo_not_found "/etc/inetd.conf"
+  fi
+  if [ -d /etc/xinetd.d ]; then
+    # Print enabled r-services in xinetd
+    for f in /etc/xinetd.d/*; do
+      [ -f "$f" ] || continue
+      if grep -qiE '\b(service|disable)\b' "$f" 2>/dev/null; then
+        if grep -qiE 'service\s+(rsh|rlogin|rexec|shell|login|exec)\b' "$f" 2>/dev/null; then
+          # Only warn if not disabled
+          if ! grep -qiE '^\s*disable\s*=\s*yes\b' "$f" 2>/dev/null; then
+            echo "  $(basename "$f") may enable r-services:"; grep -iE '^(\s*service|\s*disable)' "$f" 2>/dev/null | sed 's/^/    /'
+          fi
+        fi
+      fi
+    done
+  else
+    echo_not_found "/etc/xinetd.d"
+  fi
+
+  echo ""
+  print_3title "Installed r-service server packages"
+  if command -v dpkg >/dev/null 2>&1; then
+    dpkg -l 2>/dev/null | grep -E '\b(rsh-server|rsh-redone-server|krb5-rsh-server|inetutils-inetd|openbsd-inetd|xinetd|netkit-rsh)\b' || echo "  No related packages found via dpkg"
+  elif command -v rpm >/dev/null 2>&1; then
+    rpm -qa 2>/dev/null | grep -Ei '\b(rsh|rlogin|rexec|xinetd)\b' || echo "  No related packages found via rpm"
+  else
+    echo_not_found "dpkg|rpm"
+  fi
+
+  echo ""
+  print_3title "/etc/hosts.equiv and /etc/shosts.equiv"
+  for f in /etc/hosts.equiv /etc/shosts.equiv; do
+    if [ -f "$f" ]; then
+      perms=$(stat -c %a "$f" 2>/dev/null)
+      owner=$(stat -c %U "$f" 2>/dev/null)
+      echo "  $f (perm $perms, owner $owner)"
+      # Print non-comment lines
+      awk 'NF && $0 !~ /^\s*#/ {print "    " $0}' "$f" 2>/dev/null
+      if grep -qEv '^\s*#|^\s*$' "$f" 2>/dev/null; then
+        if grep -qE '(^|\s)\+' "$f" 2>/dev/null; then
+          echo "    [!] Wildcard '+' trust found"
+        fi
+      fi
+    fi
+  done
+
+  echo ""
+  print_3title "Per-user .rhosts files"
+  any_rhosts=false
+  for rfile in /root/.rhosts /home/*/.rhosts; do
+    if [ -f "$rfile" ]; then
+      any_rhosts=true
+      perms=$(stat -c %a "$rfile" 2>/dev/null)
+      owner=$(stat -c %U "$rfile" 2>/dev/null)
+      echo "  $rfile (perm $perms, owner $owner)"
+      awk 'NF && $0 !~ /^\s*#/ {print "    " $0}' "$rfile" 2>/dev/null
+      # Warn on insecure perms (group/other write)
+      g=$(printf "%s" "$perms" | cut -c2)
+      o=$(printf "%s" "$perms" | cut -c3)
+      if [ "${g:-0}" -ge 2 ] || [ "${o:-0}" -ge 2 ]; then
+        echo "    [!] Insecure permissions (group/other write)"
+      fi
+    fi
+  done
+  if ! $any_rhosts; then echo_not_found ".rhosts"; fi
+
+  echo ""
+  print_3title "PAM rhosts authentication"
+  shown=false
+  for p in /etc/pam.d/rlogin /etc/pam.d/rsh; do
+    if [ -f "$p" ]; then
+      shown=true
+      echo "  $p:"
+      (grep -nEi 'pam_rhosts|pam_rhosts_auth' "$p" 2>/dev/null || echo "    no pam_rhosts* lines") | sed 's/^/    /'
+    fi
+  done
+  if ! $shown; then echo_not_found "/etc/pam.d/rlogin|rsh"; fi
+
+  echo ""
+  print_3title "SSH HostbasedAuthentication"
+  if [ -f /etc/ssh/sshd_config ]; then
+    if grep -qiE '^[^#]*HostbasedAuthentication\s+yes' /etc/ssh/sshd_config 2>/dev/null; then
+      echo "  HostbasedAuthentication yes (check /etc/shosts.equiv or ~/.shosts)"
+    else
+      echo "  HostbasedAuthentication no or not set"
+    fi
+  else
+    echo_not_found "/etc/ssh/sshd_config"
+  fi
+
+  echo ""
+  print_3title "Potential DNS control indicators (local)"
+  (ps -eo comm,args 2>/dev/null | grep -Ei '(^|/)(pdns|pdns_server|pdns_recursor|powerdns-admin)( |$)' | grep -Ev 'grep|bash' || echo "  Not detected")
+
+  echo ""
+fi
+