WordPress

Usage

Description

The CrowdSec Bouncer plugin for WordPress has been designed to protect WordPress websites from various malicious activities by using CrowdSec technology.

N.B.: it's important to understand the scope and limitations of this bouncer, as described in the Understanding the limitations of the bouncer section.

Prerequisites

To be able to use this Remediation component, the first step is to install CrowdSec v1.

CrowdSec is only in charge of the "detection", and won't block anything on its own. You need to deploy a remediation to "apply" decisions.

Please note that first and foremost CrowdSec must be installed on a server that is accessible via the WordPress site.

Features

When a user is suspected by CrowdSec to be malevolent, this component will either send him/her a captcha to resolve or simply a page notifying that access is denied. If the user is considered as a clean user, he will access the page as normal.

By default, the ban wall is displayed as below:

By default, the captcha wall is displayed as below:

Please note that it is possible to customize all the colors of these pages in a few clicks so that they integrate best with your design.

On the other hand, all texts are also fully customizable. This will allow you, for example, to present translated pages in your users’ language.

Understanding the limitations of the bouncer

While this plugin provides effective protection for most scenarios by intercepting and bouncing web requests that go through the WordPress loading process, there are inherent limitations to this approach. These limitations can create potential gaps in coverage, which you should be aware of:

1. Requests to PHP files outside the WordPress Core loading process

   Since this plugin is loaded as part of the WordPress core process, it will not attempt to retrieve or apply a remediation if a custom public PHP script is accessed directly. To ensure all PHP scripts are covered, consider enabling the auto_prepend_file mode.

2. Requests to Non-PHP Files (e.g. .env or other static files)

   Requests for non-PHP files, such as .env or other static files, are not handled by this plugin. As this limitation is tied to the nature of PHP itself, you may need to implement additional server-level protections (e.g., strict file permissions or blocking access to sensitive files through server configuration) to secure such files. For example, you can deny access to hidden files, using the Nginx directive

   location ~ /\. {
       deny all;
   }

   or the Apache one:

   <FilesMatch "^\.">
       Require all denied
   </FilesMatch>

By understanding these limitations, you can take additional steps to secure your site comprehensively and complement the protection offered by the CrowdSec Bouncer plugin.

Configurations

This plugin comes with configurations that you will find under CrowdSec admin section.

These configurations are divided in three main parts : CrowdSec, Theme customization and Advanced.

General settings

In the CrowdSec part, you will set your connection details and refine bouncing according to your needs. You will also be able to test your settings.

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Connection details → Local API URL

Url to join your CrowdSec Local API.

If the CrowdSec Agent is installed on this server, you could set this field to http://localhost:8080.

Default to http://localhost:8080

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Connection details → Authentication type

Choose between Bouncer API key and TLS certificates (pki) authentication.

TLS authentication is only available if you use CrowdSec agent with a version superior to 1.4.0. Please see CrowdSec documentation.

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Connection details → Bouncer API key

Key generated by the cscli command.

Only if you chose Bouncer API key as authentication type.

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Connection details → Path to the bouncer certificate

Absolute path. Make sure this file is not publicly accessible. See security note below.

Example: /var/crowdsec/tls/bouncer.pem.

Only if you chose TLS certificates as authentication type.

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Connection details → Path to the bouncer key

Absolute path. Make sure this file is not publicly accessible. See security note below.

Example: /var/crowdsec/tls/bouncer-key.pem.

Only if you chose TLS certificates as authentication type.

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Connection details → Verify peer

This option determines whether request handler verifies the authenticity of the peer's certificate.

Only if you chose TLS certificates as authentication type.

When negotiating a TLS or SSL connection, the server sends a certificate indicating its identity. If Verify peer is checked, request handler verifies whether the certificate is authentic. This trust is based on a chain of digital signatures, rooted in certification authority (CA) certificate you supply using the Path to the CA used to process for peer verification setting below.

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Connection details → Path to the CA certificate used to process peer verification

Absolute path. Make sure this file is not publicly accessible. See security note below.

Example: /var/crowdsec/tls/ca-chain.pem.

Only if you chose TLS certificates as authentication type.

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Connection details → Use cURL to call Local API

By default, file_get_contents method is used to call Local API. This method requires to have enabled the option allow_url_fopen. Here, you can choose to use cURL requests instead. Beware that in this case, you need to have php cURL extension installed and enabled on your system.

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Connection details → Local API request timeout

By default, the maximum allowed time to perform a Local API request is 120 seconds. You can change this setting here. If you set a negative value, request timeout will be unlimited.

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Bouncing → Bouncing level

Choose if you want to apply CrowdSec directives (Normal bouncing) or be more permissive (Flex bouncing).

With the Flex mode, it is impossible to accidentally block access to your site to people who don’t deserve it. This mode makes it possible to never ban an IP but only to offer a captcha, in the worst-case scenario.

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Bouncing → Public website only

If enabled, the admin view is not bounced.

This is not recommended in production.

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Test your settings → Test bouncing

Click the "Test bouncing" button and the configured bouncer will try to get the remediation (bypass, captcha or ban) for the IP entered in the text field. By default, tested IP is the current detected remote IP.

This test allows you to know if your connection, bouncing and cache settings are correct.

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Test your settings → Test geolocation

Click the "Test geolocation" button to try getting country for the IP entered in the text field.

This test allows you to know if your geolocation settings are correct.

Theme customization

In the Theme customization part, you can modify texts and colors of ban and captcha walls.

Advanced settings

In the Advanced part, you can enable/disable the stream mode, choose your cache system for your CrowdSec Local API, handle your remediation policy, manage geolocation feature, adjust some debug parameters and testing parameters.

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Communication mode to the API → Enable the "Stream mode"

Choose if you want to enable the stream mode or stay in live mode.

By default, the live mode is enabled. The first time a stranger connects to your website, this mode means that the IP will be checked directly by the CrowdSec API. The rest of your user’s browsing will be even more transparent thanks to the fully customizable cache system.

But you can also activate the stream mode. This mode allows you to constantly feed the bouncer with the malicious IP list via a background task (CRON), making it to be even faster when checking the IP of your visitors. Besides, if your site has a lot of unique visitors at the same time, this will not influence the traffic to the API of your CrowdSec instance.

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Communication mode to the API → Resync decisions each (stream mode only)

With the stream mode, every decision is retrieved in an asynchronous way. Here you can define the frequency of this cache refresh.

N.B : There is also a refresh button if you want to refresh the cache manually.

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Caching configuration → Technology

Choose the cache technology that will use your CrowdSec Local API.

The File system cache is faster than calling Local API. Redis or Memcached is faster than the File System cache.

N.B. : There are also a Clear now button fo all cache technologies and a Prune now button dedicated to the file system cache.

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Caching configuration → Recheck clean IPs each (live mode only)

The duration between re-asking Local API about an already checked clean IP.

Minimum 1 second. Note that this setting can not be apply in stream mode.

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Caching configuration → Recheck bad IPs each (live mode only)

The duration between re-asking Local API about an already checked bad IP.

Minimum 1 second. Note that this setting can not be apply in stream mode.

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Caching configuration → Captcha flow cache lifetime

The lifetime of cached captcha flow for some IP.

If a user has to interact with a captcha wall, we store in cache some values in order to know if he has to resolve or not the captcha again.

Minimum 1 second. Default: 86400 seconds.

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Caching configuration → Redis DSN (if applicable)

Fill in this field only if you have chosen the Redis cache.

Example of DSN: redis://localhost:6379.

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Caching configuration → Memcached DSN (if applicable)

Fill in this field only if you have chosen the Memcached cache.

Example of DSN: memcached://localhost:11211.

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AppSec component → Enable AppSec

Enable if you want to ask the AppSec component for a remediation based on the current request, in case the initial LAPI remediation is a bypass.

Not available if you use TLS certficates as authentication type.

For more information on the AppSec component, please refer to the documentation.

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AppSec component → Url

Your AppSec component url. Default to http://localhost:7422

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AppSec component → Request timeout

Maximum execution time (in milliseconds) for an AppSec request.

Set a negative value to allow unlimited timeout

Default to 400.

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AppSec component → Fallback to

What remediation to apply when AppSec call has failed due to a timeout.

Recommended: captcha. Default: bypass.

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AppSec component → Maximum body size

Maximum size of the request body (in KB). Default to 1024.

If exceeded, the action defined below will be applied.

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AppSec component → Body size exceeded action

Action to take when the request body size exceeds the maximum body size.

Default to headers_only.

• Headers Only: (recommended) Only headers of the original request are sent to the AppSec component. The body is not sent.
• Block: The request is considered as malicious and a ban remediation is returned, without calling AppSec.
• Allow: (not recommended): The request is considered as clean and a bypass remediation is returned, without calling AppSec.

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Remediation → Fallback to

Choose which remediation to apply when CrowdSec advises unhandled remediation.

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Remediation → Trust these CDN IPs (or Load Balancer, HTTP Proxy)

If you use a CDN, a reverse proxy or a load balancer, it is possible to indicate in the bouncer settings the IP ranges of these devices in order to be able to check the IP of your users. For other IPs, the bouncer will not trust the X-Forwarded-For header.

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Remediation → Hide CrowdSec mentions

Enable if you want to hide CrowdSec mentions on the Ban and Captcha walls.

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Geolocation → Enable geolocation feature

Enable if you want to use also CrowdSec country scoped decisions. If enabled, bounced IP will be geolocalized and the final remediation will take into account any country related decision.

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Geolocation → Geolocation type

For now, only Maxmind database type is allowed

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Geolocation → MaxMind database type

Choose between Country and City.

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Geolocation → Path to the MaxMind database

Absolute path. Make sure this file is not publicly accessible. See security note below.

Example: /var/crowdsec/geolocation/Geoloc-country.mmdb folder.

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Geolocation → Geolocation cache lifetime

The lifetime of cached country geolocation result for some IP. Default: 86400. Set 0 to disable caching. Enabling this will avoid multiple call to the geolocation system (e.g. MaxMind database)

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Debug mode → Enable debug mode

Enable if you want to see some debug information in a specific log file.

When this mode is enabled, a debug.log file will be written in wp-content/uploads/crowdsec/logs folder.

Make sure this path is not publicly accessible. See security note below.

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Debug mode → Disable prod log

By default, a prod.log file will be written in wp-content/uploads/crowdsec/logs folder.

Make sure this path is not publicly accessible. See security note below.

You can disable this log here.

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Debug mode → Custom User-Agent

By default, User-Agent used to call LAPI has the following format: csphplapi_WordPress.

You can use this field to add a custom suffix: csphplapi_WordPress[custom-suffix].

This can be useful to debug crowdsec logs when using multiple WordPress sites with multiple bouncer plugins.

Only alphanumeric characters ([A-Za-z0-9]) are allowed with a maximum of 5 characters.

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Display errors → Enable errors display

When this mode is enabled, you will see every unexpected bouncing errors in the browser. Should be disabled in production.

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Auto prepend file mode → Enable auto_prepend_file mode

This setting allows the bouncer to bounce IPs before running any PHP script in the project.

Make sure the generated standalone-settings.php file is not publicly accessible. See security note below.

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Test settings → Forced test IP

This Ip will be used instead of the current detected browser IP.

Must be empty in production.

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Test settings → Forced test X-Forwarded-For IP

This Ip will be used instead of the current X-Forwarded-For Ip if any.

Must be empty in production.

Security

Some files used or created by this plugin must be protected from direct access attempts:

• The standalone-settings.php file created in the wp-content/plugins/crowdsec/inc folder for the Auto Prepend File mode
• Log files are created in the wp-content/uploads/crowdsec/logs folder
• Cache files of the File system cache are created in the wp-content/uploads/crowdsec/cache folder
• TLS authentication files are located in a user defined path
• Geolocation database files are located in a user defined path

N.B.:

• There is no need to protect standalone-settings.php file if you don't use auto_prepend_file mode.

• There is no need to protect cache files if you are using Redis or Memcached cache systems.

• There is no need to protect log files if you disable debug and prod logging.

• There is no need to protect TLS files if you use Bouncer API key authentication type.

• There is no need to protect geolocation files if you don't use the geolocation feature.

Nginx

If you are using Nginx, you should add a directive in your website configuration file to deny access to these folders.

For log, cache and standalone setting files, this could be done with the following snippet:

server {
   ...
   ...
   ...
   # Deny all attempts to access some folders of the crowdsec plugin
   location ~ /crowdsec/(cache|logs|inc/standalone-settings) {
           deny all;
   }
   ...
   ...
}

Apache

If you are using Apache, the plugin root folder already contain the required .htaccess file to protect log,
cache and standalone setting files:

Redirectmatch 403 wp-content/uploads/crowdsec/logs/
Redirectmatch 403 wp-content/uploads/crowdsec/cache/
Redirectmatch 403 wp-content/plugins/crowdsec/inc/standalone-settings

Auto Prepend File mode

By default, this extension will bounce every web requests that pass through the classical process of WordPress core loading. This implies that if another php public script is called (any of your custom public php script for example) or if you are using some plugin that bypass the WordPress core load process (as the WP Super Cache plugin in Simple mode for example), bouncing will not be effective.

To ensure that any php script will be bounced if called from a browser, you should try the auto prepend file mode.

In this mode, every browser access to a PHP script will be bounced.

To enable the auto prepend file mode, you have to configure your server by adding an auto_prepend_file directive for your php setup.

N.B.:

• In this mode, a setting file inc/standalone-settings.php will be generated each time you save the CrowdSec plugin configuration from the WordPress admin. Make sure this file is not publicly accessible. See security note above.

• This mode requires to have the plugin installed in the wp-content/plugins/crowdsec folder. This is the default installation folder of WordPress plugins.

Adding an auto_prepend_file directive can be done in different ways:

PHP

You should add this line to a .ini file :

auto_prepend_file = /wordpress-root-directory/wp-content/plugins/crowdsec/inc/standalone-bounce.php

Nginx

If you are using Nginx, you should modify your Magento 2 nginx configuration file by adding a fastcgi_param directive. The php block should look like below:

location ~ \.php$ {
    ...
    ...
    ...
    fastcgi_param PHP_VALUE "auto_prepend_file=/wordpress-root-directory/wp-content/plugins/crowdsec/inc/standalone-bounce.php";
}

Apache

If you are using Apache, you should add this line to your .htaccess file:

php_value auto_prepend_file "/wordpress-root-directory/wp-content/plugins/crowdsec/inc/standalone-bounce.php"

Multisite usage

If you are using the multisite WordPress feature, the bouncer plugin has to be network activated and configurations will be used for all sites of the network. This means that every individual site on your network will be protected by the bouncer with the same settings.

Differences with a single installation

In a WordPress multisite installation, CrowdSec configurations are accessible via the My Sites -> Network admin left panel.

Settings are stored in the wp_sitemeta table instead of the wp_options table for a single WordPress installation.

Resources

Feel free to look at the associated article for more configuration options and tweaks.

Installation

Add the plugin

The component itself can be installed from the marketplace in WordPress back-office.

Installing the CrowdSec WordPress plugin is as easy as installing any other WordPress plugin:

• Click Plugins in the left navigation on your site’s dashboard.
• Type CrowdSec in the text field to the right. Hit enter.
• In the CrowdSec plugin click Install Now
• Once installed click Activate.

WordPress Marketplace

You can find this plugin on the WordPress Plugins Marketplace.

Technical notes

We explain here each important technical decision used to design this plugin.

How to use system CRON instead of wp-cron?

Add define('DISABLE_WP_CRON', true); in wp-config.php then enter this command line on the WordPress host command line:

(crontab -l && echo "* * * * * wget -q -O - http://<host>:<port>/wp-cron.php?doing_wp_cron >/dev/null 2>&1") | crontab -

Note: replace <host:<port> with the local url of your website

More info here.

Developer guide

See Developer guide

License

MIT