CloudFlare Under Attack Mode Automation

Installation
1

hello discourse…

few days ago my small server has got ddos attack.
even though it can be proxied by CF but still some attacks can penetrate the server. until the server gets CPU reads up to 60% to 80%…
and it can be prevented by turning on “UnderAttackMode”
sometimes I’m also distracted to enter CF which is only to manually turn on “UnderAttackMode”

after google it turns out there are several articles that say auto UnderAttackMode through reading the CPU itself…

CF AUTO

#!/bin/bash
# Cloudflare Auto Under Attack Mode = CF Auto UAM
# version 0.99beta

# Security Level Enums
SL_OFF=0
SL_ESSENTIALLY_OFF=1
SL_LOW=2
SL_MEDIUM=3
SL_HIGH=4
SL_UNDER_ATTACK=5

# Security Level Strings
SL_OFF_S="off"
SL_ESSENTIALLY_OFF_S="essentially_off"
SL_LOW_S="low"
SL_MEDIUM_S="medium"
SL_HIGH_S="high"
SL_UNDER_ATTACK_S="under_attack"

#config
debug_mode=0 # 1 = true, 0 = false, adds more logging & lets you edit vars to test the script
install_parent_path="/home"
cf_email=""
cf_apikey=""
cf_zoneid=""
upper_cpu_limit=35 # 10 = 10% load, 20 = 20% load.  Total load, taking into account # of cores
lower_cpu_limit=5
regular_status=$SL_HIGH
regular_status_s=$SL_HIGH_S
time_limit_before_revert=$((60 * 5)) # 5 minutes by default
#end config

# Functions

install() {
  mkdir $install_parent_path"/cfautouam" &>/dev/null

  cat >$install_parent_path"/cfautouam/cfautouam.service" <<EOF
[Unit]
Description=Automate Cloudflare Under Attack Mode
[Service]
ExecStart=$install_parent_path/cfautouam/cfautouam.sh
EOF

  cat >$install_parent_path"/cfautouam/cfautouam.timer" <<EOF
[Unit]
Description=Automate Cloudflare Under Attack Mode
[Timer]
OnBootSec=60
OnUnitActiveSec=5
AccuracySec=1
[Install]
WantedBy=timers.target
EOF

  chmod +x $install_parent_path"/cfautouam/cfautouam.service"
  systemctl enable $install_parent_path"/cfautouam/cfautouam.timer"
  systemctl enable $install_parent_path"/cfautouam/cfautouam.service"
  systemctl start cfautouam.timer
  echo "$(date) - cfautouam - Installed" >>$install_parent_path"/cfautouam/cfautouam.log"
  exit
}

uninstall() {
  systemctl stop cfautouam.timer
  systemctl stop cfautouam.service
  systemctl disable cfautouam.timer
  systemctl disable cfautouam.service
  rm $install_parent_path"/cfautouam/cfstatus" &>/dev/null
  rm $install_parent_path"/cfautouam/uamdisabledtime" &>/dev/null
  rm $install_parent_path"/cfautouam/uamenabledtime" &>/dev/null
  rm $install_parent_path"/cfautouam/cfautouam.timer"
  rm $install_parent_path"/cfautouam/cfautouam.service"
  echo "$(date) - cfautouam - Uninstalled" >>$install_parent_path"/cfautouam/cfautouam.log"
  exit
}

disable_uam() {
  curl -X PATCH "https://api.cloudflare.com/client/v4/zones/$cf_zoneid/settings/security_level" \
    -H "X-Auth-Email: $cf_email" \
    -H "X-Auth-Key: $cf_apikey" \
    -H "Content-Type: application/json" \
    --data "{\"value\":\"$regular_status_s\"}" &>/dev/null

  # log time
  date +%s >$install_parent_path"/cfautouam/uamdisabledtime"

  echo "$(date) - cfautouam - CPU Load: $curr_load - Disabled UAM" >>$install_parent_path"/cfautouam/cfautouam.log"
}

enable_uam() {
  curl -X PATCH "https://api.cloudflare.com/client/v4/zones/$cf_zoneid/settings/security_level" \
    -H "X-Auth-Email: $cf_email" \
    -H "X-Auth-Key: $cf_apikey" \
    -H "Content-Type: application/json" \
    --data '{"value":"under_attack"}' &>/dev/null

  # log time
  date +%s >$install_parent_path"/cfautouam/uamenabledtime"

  echo "$(date) - cfautouam - CPU Load: $curr_load - Enabled UAM" >>$install_parent_path"/cfautouam/cfautouam.log"
}

get_current_load() {
  currload=$(top -bn1 | grep "Cpu(s)" | sed "s/.*, *\([0-9.]*\)%* id.*/\1/" | awk '{print 100 - $1}')
  currload=$(echo "$currload/1" | bc)
  return $currload
}

get_security_level() {
  curl -X GET "https://api.cloudflare.com/client/v4/zones/$cf_zoneid/settings/security_level" \
    -H "X-Auth-Email: $cf_email" \
    -H "X-Auth-Key: $cf_apikey" \
    -H "Content-Type: application/json" 2>/dev/null |
    awk -F":" '{ print $4 }' | awk -F',' '{ print $1 }' | tr -d '"' >$install_parent_path"/cfautouam/cfstatus"

  security_level=$(cat $install_parent_path"/cfautouam/cfstatus")

  case $security_level in
  "off")
    return $SL_OFF
    ;;
  "essentially_off")
    return $SL_ESSENTIALLY_OFF
    ;;
  "low")
    return $SL_LOW
    ;;
  "medium")
    return $SL_MEDIUM
    ;;
  "high")
    return $SL_HIGH
    ;;
  "under_attack")
    return $SL_UNDER_ATTACK
    ;;
  *)
    return 100 # error
    ;;
  esac
}

main() {
  # Get current protection level & load
  get_security_level
  curr_security_level=$?
  get_current_load
  curr_load=$?

  if [ $debug_mode == 1 ]; then
    debug_mode=1 # random inconsequential line needed to hide a dumb shellcheck error
	#edit vars here to debug the script
    #curr_load=5
    #time_limit_before_revert=15
  fi

  # If UAM was recently enabled

  if [[ $curr_security_level == "$SL_UNDER_ATTACK" ]]; then
    uam_enabled_time=$(<$install_parent_path"/cfautouam/uamenabledtime")
    currenttime=$(date +%s)
    timediff=$((currenttime - uam_enabled_time))

    # If time limit has not passed do nothing
    if [[ $timediff -lt $time_limit_before_revert ]]; then
        if [ $debug_mode == 1 ]; then
          echo "$(date) - cfautouam - CPU Load: $curr_load - time limit has not passed regardless of CPU - do nothing" >>$install_parent_path"/cfautouam/cfautouam.log"
        fi
        exit
    fi

    # If time limit has passed & cpu load has normalized, then disable UAM
    if [[ $timediff -gt $time_limit_before_revert && $curr_load -lt $lower_cpu_limit ]]; then
        if [ $debug_mode == 1 ]; then
          echo "$(date) - cfautouam - CPU Load: $curr_load - time limit has passed - CPU Below threshhold" >>$install_parent_path"/cfautouam/cfautouam.log"
        fi
        disable_uam
        exit
    fi

    # If time limit has passed & cpu load has not normalized, wait
    if [[ $timediff -gt $time_limit_before_revert && $curr_load -gt $lower_cpu_limit ]]; then
      if [ $debug_mode == 1 ]; then
        echo "$(date) - cfautouam - CPU Load: $curr_load - time limit has passed but CPU above threshhold, waiting out time limit" >>$install_parent_path"/cfautouam/cfautouam.log"
      fi
    fi
    exit
  fi

  # If UAM is not enabled, continue

  # Enable and Disable UAM based on load

  #if load is higher than limit
  if [[ $curr_load -gt $upper_cpu_limit && $curr_security_level == "$regular_status" ]]; then
    enable_uam
  #else if load is lower than limit
  elif [[ $curr_load -lt $lower_cpu_limit && $curr_security_level == "$SL_UNDER_ATTACK" ]]; then
    disable_uam
  else
    if [ $debug_mode == 1 ]; then
      echo "$(date) - cfautouam - CPU Load: $curr_load - no change necessary" >>$install_parent_path"/cfautouam/cfautouam.log"
    fi
  fi
}

# End Functions

# Main -> command line arguments

if [ "$1" = '-install' ]; then
  install
  echo "$(date) - cfautouam - Installed" >>$install_parent_path"/cfautouam/cfautouam.log"
  exit
elif [ "$1" = '-uninstall' ]; then
  uninstall
  echo "$(date) - cfautouam - Uninstalled" >>$install_parent_path"/cfautouam/cfautouam.log"
  exit
elif [ "$1" = '-enable_uam' ]; then
  echo "$(date) - cfautouam - UAM Manually Enabled" >>$install_parent_path"/cfautouam/cfautouam.log"
  enable_uam
  exit
elif [ "$1" = '-disable_uam' ]; then
  echo "$(date) - cfautouam - UAM Manually Disabled" >>$install_parent_path"/cfautouam/cfautouam.log"
  disable_uam
  exit
elif [ -z "$1" ]; then
  main
  exit
else
  echo "cfautouam - Invalid argument"
  exit
fi

I tried according to what was explained but it doesn’t work… is there another way?

2

Having something which ties CPU utilization to whether a host is being attacked might work with php websites, but remember that rebuilds and upgrades are very CPU-heavy and would likely trigger this too…

1 Like
3

yes that is very true. regarding the CPU every time you update and upgrade anything about Discourse always gets a very high CPU reading… that’s not why it’s possible every time to update… maybe you can stop this script and after updating then run again…

for the first DDoS attack I need this script running on my server to deal with the second attack and maybe I have blocked every ASN and their IP BOT immediately. the DDoSers will update their ASN and IP, therefore I have to find a way to block the surprise attack

4

Are you sure they aren’t just bypassing Cloudflare via a leaked IP address?

1 Like
5

there are some Discourse friends suggesting that the server only accepts ip rather than just cloudflare and there are also some rules in WAF. and I don’t think I will be able to login to the server or ddos for the 2nd time