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" $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/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?

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…

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

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

CloudFlare Under Attack Mode Automation

Product Support Self-hosting

Stephen (Stephen) December 18, 2022, 2:26pm 4

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

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CloudFlare Under Attack Mode Automation

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