CrowdSec Cloudflare Worker

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warning

This Remediation Component heavily relies on Cloudflare Workers and KV store. It works best on a paid Workers subscription. More explanation in the chapter Test with Cloudflare free plan

warning

After configuring and starting the Remediation Component, please see the setting up worker fail mode section.

This Remediation Component (aka Bouncer) deploys a Cloudflare Worker in front of a Cloudflare Zone/Website, which checks if incoming request's IP address/Country/AS is present in a KV store and takes necessary remedial actions. It also periodically updates the KV store with CrowdSec LAPI's decisions.

Installation

Using packages

Packages for crowdsec-cloudflare-worker-bouncer are available on our repositories. You need to pick the package accord to your firewall system :

Debian/Ubuntu

sudo apt install crowdsec-cloudflare-worker-bouncer

RHEL/Centos/Fedora

sudo yum install crowdsec-cloudflare-worker-bouncer

Then run the following commands to setup your Remediation Component:

sudo crowdsec-cloudflare-worker-bouncer -g <CLOUDFLARE_TOKEN1>,<CLOUDFLARE_TOKEN2> -o /etc/crowdsec/bouncers/crowdsec-cloudflare-worker-bouncer.yaml # auto-generate cloudflare config for provided space separated tokens 
sudo vi /etc/crowdsec/bouncers/crowdsec-cloudflare-worker-bouncer.yaml # review config and set `crowdsec.lapi_key` if haven't alread
sudo systemctl start crowdsec-cloudflare-worker-bouncer # the Remediation Component now syncs the crowdsec decisions with cloudflare components.

warning

Please configure your server to emit real IPs rather than cloudflare IPs in logs, so crowdsec can function properly. See how to here

info

If your Remediation Component is not installed on the same machine than LAPI, don't forget to set the crowdsec_lapi_url and crowdsec.lapi_key in the configuration file /etc/crowdsec/bouncers/crowdsec-cloudflare-worker-bouncer.yaml

note

You need to run sudo crowdsec-cloudflare-worker-bouncer -d to cleanup exisiting cloudflare components created by Remediation Component before editing the config files.

note

You can run sudo crowdsec-cloudflare-worker-bouncer -g <CLOUDFLARE_TOKEN1>,<CLOUDFLARE_TOKEN2> -o /etc/crowdsec/bouncers/crowdsec-cloudflare-worker-bouncer.yaml to generate the configuration by discovering all the accounts and the zones associated with the provided tokens.

Manual Installation

Assisted

Download the latest release.

tar xzvf crowdsec-cloudflare-worker-bouncer.tgz
cd crowdsec-cloudflare-worker-bouncer/
sudo ./install.sh
sudo crowdsec-cloudflare-worker-bouncer -g <CLOUDFLARE_TOKEN1>,<CLOUDFLARE_TOKEN2> -o /etc/crowdsec/bouncers/crowdsec-cloudflare-worker-bouncer.yaml # auto-generate cloudflare config for provided tokens 
sudo vi /etc/crowdsec/bouncers/crowdsec-cloudflare-worker-bouncer.yaml # review config and set `crowdsec.lapi_key` if haven't already
sudo systemctl start crowdsec-cloudflare-worker-bouncer # the Remediation Component now syncs the crowdsec decisions with cloudflare components.

From source

⚠️ requires go >= 1.20

git clone https://github.com/crowdsecurity/cs-cloudflare-worker-bouncer
cd cs-cloudflare-worker-bouncer
make release
cd cd crowdsec-cloudflare-worker-bouncer-*
./crowdsec-cloudflare-worker-bouncer -g <CLOUDFLARE_TOKEN1>,<CLOUDFLARE_TOKEN2> -o /etc/crowdsec/bouncers/crowdsec-cloudflare-worker-bouncer.yaml # auto-generate cloudflare config for provided space separated tokens
sudo vi /etc/crowdsec/bouncers/crowdsec-cloudflare-worker-bouncer.yaml # review config and set `crowdsec.lapi_key` if haven't already
sudo systemctl start crowdsec-cloudflare-worker-bouncer

How it works

The Remediation Component does the following:

1. Create a Cloudflare Worker and a Worker KV per configured account.
2. Create a Worker Route(s) per configured zone. Any request matching the route would be handled by the worker.
3. For every matching incoming request, the worker checks whether it's IP, Country and AS have a decision against. It checks for this in it's KV store. If found it performs the corresponding remediation.
4. The Remediation Component also periodically updates the KV store with the latest decisions from CrowdSec.

Configuration

crowdsec_config:
  lapi_key: ${API_KEY}
  lapi_url: ${CROWDSEC_LAPI_URL}
  update_frequency: 10s
  include_scenarios_containing: []
  exclude_scenarios_containing: []
  only_include_decisions_from: []
  insecure_skip_verify: false
  key_path: ""  # Used for TLS authentification with CrowdSec LAPI
  cert_path: "" # Used for TLS authentification with CrowdSec LAPI
  ca_cert_path: "" # Used for TLS authentification with CrowdSec LAPI

cloudflare_config:
    accounts:
        - id: <ACCOUNT_ID>
          zones:
            - zone_id: <ZONE_ID> # crowdflare.co.uk
              actions: # Supported Actions [captcha, ban]
                - captcha
              default_action: captcha # Supported Actions [captcha, ban, none]
              routes_to_protect: []
              turnstile:
                enabled: true
                rotate_secret_key: true
                rotate_secret_key_every: 168h0m0s 
                mode: managed # Supported Modes "managed"|"invisible"|"non-interactive"
          token: <CLOUDFLARE_ACCOUNT_TOKEN>
          account_name: owner@example.com

log_level: info
log_media: "stdout"
log_dir: "/var/log/"
ban_template_path: "" # set to empty to use default template

prometheus:
    enabled: true
    listen_addr: 127.0.0.1
    listen_port: "2112"

Cloudflare Configuration

Background: In Cloudflare, each user can have access to multiple accounts. Each account can own/access multiple zones. In this context a zone can be considered as a domain. Each domain registered with cloudflare gets a distinct zone_id.

For obtaining the token:

1. Sign in as a user who has access to the desired account.

Then click this link and create the token.

Alternatively, you can go to Tokens and create the token.

The Remediation Component requires the following permissions to function:

Permission Group	Item	Permission
Account	Turnstile	Edit
Account	Workers KV Storage	Edit
Account	Workers Scripts	Edit
Account	Account Settings	Read
User	User Details	Read
Zone	DNS	Read
Zone	Workers Routes	Edit
Zone	Zone	Read

info

By default, the token will be scopped to all accounts / zones you have access to.
We recommend scoping the token only to the required accounts and zones.

warning

This remediation component require each configured to have at least one A or AAAA records.
If you have zones without them (eg, with only CNAME records), exclude them from the scope.
The bouncer will try to automatically ignore such zones, but if it fails to do so for any reason, you might incur higher KV storage charges.

To automatically generate config, check the helper section below.

Helpers

The binary has built in helper scripts to do various operations.

Auto config generator

Generates config by discovering all the accounts and the zones associated with provided list of tokens.

Example Usage:

sudo crowdsec-cloudflare-worker-bouncer -g <TOKEN_1>,<TOKEN_2>...  -o cfg.yaml
cat cfg.yaml  > /etc/crowdsec/bouncers/crowdsec-cloudflare-worker-bouncer.yaml

note

This script only generates cloudflare related config. By default it refers to the config at /etc/crowdsec/bouncers/crowdsec-cloudflare-worker-bouncer.yaml for crowdsec configuration.

Using custom config:

sudo crowdsec-cloudflare-worker-bouncer -c ./cfg.yaml -g <TOKEN_1>,<TOKEN_2>... 

Cloudflare Cleanup

This deletes all the Cloudflare infrastructure which was created by the Remediation Component.

Example Usage:

sudo crowdsec-cloudflare-worker-bouncer -d 

Setting up the worker route fail mode

The Remediation Component creates worker routes to make the workers act as a reverse proxy for your origin servers. The worker routes are created with the failover mode set to Fail Closed. There's no public Cloudflare API we can use to change/update it to Fail Open mode.

With Fail Closed mode, Routes in fail closed mode will display a Cloudflare 1027 error page to visitors if there's an error within the worker. This error could be triggered due to quotas exceeding your plan etc. Cloudflare doesn't mention all the possible scenarios which could trigger this error page.

Thus we recommend you to manually override the failover mode to Fail Open for all the worker routes created by our Remediation Component. With Fail Open mode the requests would bypass the worker and be served directly from your origin servers. Thus your website would continue to function even if there's an error within the worker.

This can be done by following the steps below:

1. Log in to the Cloudflare dashboard and select your account.
2. For all the websites configured with the Remediation Component, do the following:
3. Click on the website's name to open the Website's Overview page.
4. Click on the Worker Routes tab from the left menu.

5. Click on the route created by the Remediation Component.
6. Click on the Edit button.
7. Click on the Request limit failure mode. Check the Fail open button.

Appendix: Test with Cloudflare free plan

Using Cloudflare's free plan with our Remediation Component requires to understand the constraints of the CloudFlare freeplan.
Despite these constraints, it's entirely feasible to leverage the Remediation Component for enhanced security.

In this section we'll guide you through:

• An overview of the Cloudflare free plan's limitations and their impact on Remediation Component functionality
• A walkthrough for deploying the Remediation Component within these constraints successfully

Understanding Cloudflare Free Plan Limitations

Our Remediation Component integrates with Cloudflare Workers and Workers KeyValue storage, subject to specific thresholds under the free plan.
For the complete detailed information, refer to Cloudflare's official documentation:

• KeyValue storage limits by plan
• Workers limits by plan

Key limitations to note for Remediation Component operation on the free plan include:

• KV write: Up to 1K per day
• Worker Requests:Up to 100k per day or 1K per minute

KV write limit of 1K per day:
It's the primary limiting factor as the full decisions list (blocklist) passed on to the Remediation Component often exceeds tens of thousands of IPs.

• It implies that the initial population of decisions in the Worker's KV will be truncated to 1K
• However, it will still periodically receive new decisions and remove expired ones.
• So, eventually you'll have many more than 1K IPs in the KV but it still diminishes the immediate effectiveness of the Remediation Component

The request quota: While the request quota might seem ample, it's essential to remember that both legitimate traffic and potential attack patterns contribute to this total.

• ⚠️ It's primordial to properly setup the failmode
• With the failmode set to passthrough, when you reach the Worker request limits your service will stay available, but the Remediation Component won't apply remediation anymore

Quick Guide : Configuring the Remediation Component on Cloudflare's Free Plan

To adapt to the free plan's constraints, we can prioritize local decision-making and manual intervention over broader community-driven blocklists.
Here's how to set it up:

1. Configuration Setup: Begin by auto-generating the Remediation Component configuration.
2. Limiting Decision Sources: Modify the configuration to prioritize decisions generated by your Security Engine and added manually.

• Using the config parameter crowdsec.only_include_decisions_from

crowdsec_config:
[...]
only_include_decisions_from: ["cscli", "crowdsec"]

3. Failmode Configuration: It's crucial to configure the failmode properly to ensure your service remains operational even when request quotas are reached.
4. Testing with manual decisions: Verify the functionality by adding decisions manually, which should be promptly reflected in KV storage and enforced by the Remediation Component.

  sudo cscli decisions add --ip 1.2.3.4 --type captcha

check your decisions has been added using:

  sudo cscli decisions list --origin cscli

And within a few seconds it will be sent to the KV and the proper remediation should be applied to the requests from the specified IP

Configuration Reference

crowdsec

Used to nest the configuration related to crowdsec.

lapi_url

string

The URL of CrowdSec LAPI. It should be accessible from the Remediation Component.

lapi_key

string

It can be obtained by running the following on the machine CrowdSec LAPI is deployed on.

sudo cscli -oraw bouncers add cloudflarebouncer # -oraw flag can discarded for human friendly output.

update_frequency

string (That is parseable by time.ParseDuration)

The Remediation Component will poll the CrowdSec every update_frequency interval. (default: 10s)

include_scenarios_containing

[ ]string

Ignore IPs banned for triggering scenarios not containing either of provided word.

Example

include_scenarios_containing: ["ssh", "http"]

exclude_scenarios_containing

[ ]string

Ignore IPs banned for triggering scenarios containing either of provided word.

Example

exclude_scenarios_containing: ["ssh", "http"]

only_include_decisions_from

[ ]string

Only include IPs banned due to decisions orginating from provided sources.

Example

only_include_decisions_from: ["cscli", "crowdsec"]

insecure_skip_verify

boolean

Skip verification of the LAPI certificate, usually used for self-signed certificates

key_path

string

Path to the private key file to use for TLS authentication with CrowdSec LAPI.

cert_path

string

Path to the certificate file to use for TLS authentication with CrowdSec LAPI.

ca_cert_path

string

Path to the CA certificate file to use for TLS authentication with CrowdSec LAPI.

cloudflare_config

Cloudflare configuration.

accounts[].id

string

The ID of the Cloudflare account.

accounts[].zones[].zone_id

string

The ID of the Cloudflare zone.

accounts[].zones[].actions

captcha | ban

Supported actions for the zone.

accounts[].zones[].default_action

captcha | ban | none

Default action to take for the zone.

accounts[].zones[].routes_to_protect

[ ]string

List of routes to protect within the zone. Example value ["example.com/"]

accounts[].zones[].turnstile.enabled

boolean

Enable or disable turnstile for the zone.

accounts[].zones[].turnstile.rotate_secret_key

boolean

Rotate the secret key for turnstile.

accounts[].zones[].turnstile.rotate_secret_key_every

string (That is parseable by time.ParseDuration)

Duration for rotating the secret key. Values should be in the format of 1h2m3s. Example value 168h0m0s for 7 days.

accounts[].zones[].turnstile.mode

Mode for turnstile. Supported values ["managed", "invisible", "non-interactive"]. See cloudflare-docs for more details.

accounts[].zones[].token

string

Cloudflare account token.

accounts[].zones[].account_name

string

Account name.

ban_template_path

string

Path to the ban template file. If not provided, the default template is used. This HTML would be rendered to requests when they are banned.

log_level

info | debug | error | warning | trace

Log level of the Remediation Component.

log_mode

stdout | file

Where the log contents are written (With file it will be written to log_dir with the name crowdsec-cloudflare-worker-bouncer.log)

log_dir

Relevant if log_mode is file. This determines where to create log file.

prometheus

Prometheus configuration.

enabled

boolean

Enable or disable Prometheus metrics.

listen_addr

string

Address to listen for Prometheus metrics. Example value 127.0.0.1

listen_port

string

Port to listen for Prometheus metrics. Example value 2112

Troubleshooting

• Metrics can be seen at http://localhost:2112/metrics