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Prevent card-attack fraud on WooCommerce stores by rate-limiting the "place order" button

License: GNU General Public License v2.0

PHP 100.00%

checkout fraud rate-limiting woocommerce

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tealou dixonl90 capuderg sprucely-designed

bh-wc-checkout-rate-limiter's Issues

Card Testing Attacks

Hello, Brian! Last year my client's WooCommerce site was hit by a credit card testing attack. So, I added reCaptcha to the checkout page and tightened some things in WordFence. Their site was hit again with another cc testing attack late last week. The Captcha plugin, as best as I can tell, works, so I've no idea how they managed to execute the script after the Captcha test is satisfied, but 1674 orders were placed by the same IP within 60 minutes. That's 27.9 attempts per minute, or one attempt every 2.15 seconds. My guess is they're using some type of Python / Selenium based script.

I'm thinking of adding your plugin to my client's website, because once an attacker's script clicks the 'Place Order' button beyond twice inside of 60 seconds, the order will stop processing, correct? That tells me once the hacker revisits his work, he'll move on to easier prey once he realizes his unsatisfactory results.

Is that the gist of how your plugin works? Are you hearing success stories from the people who have utilized it?

Thanks for your time,

Keith Robideau

README: Cloudflare Rate Limiting has become better?

I think it is now able to parse requests in much more details. I was able to set up this

Should README and maybe some of the strategy be adjusted accordingly?

Error on installation

Parse error: syntax error, unexpected 'LoggerInterface' (T_STRING), expecting function (T_FUNCTION) or const (T_CONST) in /public_html/wp-content/plugins/bh-wc-checkout-rate-limiter/Mozart/PSR-04/BrianHenryIE/WP_Logger/admin/class-admin.php on line 17

Best practices for rate limiting

I'm looking for a few pointers on how to best use this plugin, with the goal of stopping card checking activity while minimizing the annoyance of real customers. For the rate limit settings I have 2 attempts per 60 seconds, 3 attempts per 180 seconds, and nothing in the third row. In the logs I mostly see carders hitting the first limit so maybe the subsequent ones don't matter as much. I'll take any advice on offer. Thanks!

Pluging fails to activate with fatal error

I downloaded a zip file of the plugin and then uploaded it to WordPress. It loaded without issue but failed to activate with the following errors:

Warning: require_once(/home/xxxxxxxxx/public_html/wp-content/plugins/bh-wc-checkout-rate-limiter-master/vendor-prefixed/autoload.php): failed to open stream: No such file or directory in /home/xxxxxxxxx/public_html/wp-content/plugins/bh-wc-checkout-rate-limiter-master/autoload.php on line 18

Fatal error: require_once(): Failed opening required '/home/xxxxxxxxx/public_html/wp-content/plugins/bh-wc-checkout-rate-limiter-master/vendor-prefixed/autoload.php' (include_path='.:/opt/alt/php74/usr/share/pear') in /home/xxxxxxxxx/public_html/wp-content/plugins/bh-wc-checkout-rate-limiter-master/autoload.php on line 18

Can you suggest a fix?

Thanks

Fatal Error

Fatal Error:

Stack trace:
#0 /home/customer/www/domain.com/public_html/wp-content/plugins/bh-wc-checkout-rate-limiter/vendor-prefixed/wp-oop/transient-cache/src/CachePool.php(137): BrianHenryIE\Checkout_Rate_Limiter\WpOop\TransientCache\CachePool->setTransient('checkout/checko...', Array, 60)
#1 /home/customer/www/domain.com/public_html/wp-content/plugins/bh-wc-checkout-rate-limiter/vendor-prefixed/nikolaposa/rate-limit/src/Psr16RateLimiter.php(129): BrianHenryIE\Checkout_Rate_Limiter\WpOop\TransientCache\CachePool->set('checkout/checko...', Array, 60)
#2 /home/customer/www/domain.com/public_html/wp-content/plugins/bh-wc-checkout-rate-limiter/vendor-prefixed/nikolaposa/rate-limit/src/Psr16RateLimiter.php(59): BrianHenryIE\Checkout_Rate
{"type":1,"message":"Uncaught RuntimeException: set_transient() failed with key \"checkout\/checkout74.80.182.73-60\" with TTL 60s in \/home\/customer\/www\/domain.com\/public_html\/wp-content\/plugins\/bh-wc-checkout-rate-limiter\/vendor-prefixed\/wp-oop\/transient-cache\/src\/CachePool.php:322\nStack trace:\n#0 \/home\/customer\/www\/domain.com\/public_html\/wp-content\/plugins\/bh-wc-checkout-rate-limiter\/vendor-prefixed\/wp-oop\/transient-cache\/src\/CachePool.php(137): BrianHenryIE\\Checkout_Rate_Limiter\\WpOop\\TransientCache\\CachePool->setTransient('checkout\/checko...', Array, 60)\n#1 \/home\/customer\/www\/domain.com\/public_html\/wp-content\/plugins\/bh-wc-checkout-rate-limiter\/vendor-prefixed\/nikolaposa\/rate-limit\/src\/Psr16RateLimiter.php(129): BrianHenryIE\\Checkout_Rate_Limiter\\WpOop\\TransientCache\\CachePool->set('checkout\/checko...', Array, 60)\n#2 \/home\/customer\/www\/domain.com\/public_html\/wp-content\/plugins\/bh-wc-checkout-rate-limiter\/vendor-prefixed\/nikolaposa\/rate-limit\/src\/Psr16RateLimiter.php(59): BrianHenryIE\\Checkout_Rate","file":"\/home\/customer\/www\/domain.com\/public_html\/wp-content\/plugins\/bh-wc-checkout-rate-limiter\/vendor-prefixed\/wp-oop\/transient-cache\/src\/CachePool.php","line":140,"debug_backtrace":[{"file":"\/home\/customer\/www\/domain.com\/public_html\/wp-content\/plugins\/bh-wc-checkout-rate-limiter\/vendor-prefixed\/brianhenryie\/bh-wp-logger\/src\/api\/class-bh-wp-psr-logger.php","lineNumber":80,"arguments":["error","Uncaught RuntimeException: set_transient() failed with key \"checkout\/checkout74.80.182.73-60\" with TTL 60s in \/home\/customer\/www\/domain.com\/public_html\/wp-content\/plugins\/bh-wc-checkout-rate-limiter\/vendor-prefixed\/wp-oop\/transient-cache\/src\/CachePool.php:322\nStack trace:\n#0 \/home\/customer\/www\/domain.com\/public_html\/wp-content\/plugins\/bh-wc-checkout-rate-limiter\/vendor-prefixed\/wp-oop\/transient-cache\/src\/CachePool.php(137): BrianHenryIE\\Checkout_Rate_Limiter\\WpOop\\TransientCache\\CachePool->setTransient('checkout\/checko...', Array, 60)\n#1 \/home\/customer\/www\/domain.com\/public_html\/wp-content\/plugins\/bh-wc-checkout-rate-limiter\/vendor-prefixed\/nikolaposa\/rate-limit\/src\/Psr16RateLimiter.php(129): BrianHenryIE\\Checkout_Rate_Limiter\\WpOop\\TransientCache\\CachePool->set('checkout\/checko...', Array, 60)\n#2 \/home\/customer\/www\/domain.com\/public_html\/wp-content\/plugins\/bh-wc-checkout-rate-limiter\/vendor-prefixed\/nikolaposa\/rate-limit\/src\/Psr16RateLimiter.php(59): BrianHenryIE\\Checkout_Rate",{"type":1,"message":"Uncaught RuntimeException: set_transient() failed with key \"checkout\/checkout74.80.182.73-60\" with TTL 60s in \/home\/customer\/www\/domain.com\/public_html\/wp-content\/plugins\/bh-wc-checkout-rate-limiter\/vendor-prefixed\/wp-oop\/transient-cache\/src\/CachePool.php:322\nStack trace:\n#0 \/home\/customer\/www\/domain.com\/public_html\/wp-content\/plugins\/bh-wc-checkout-rate-limiter\/vendor-prefixed\/wp-oop\/transient-cache\/src\/CachePool.php(137): BrianHenryIE\\Checkout_Rate_Limiter\\WpOop\\TransientCache\\CachePool->setTransient('checkout\/checko...', Array, 60)\n#1 \/home\/customer\/www\/domain.com\/public_html\/wp-content\/plugins\/bh-wc-checkout-rate-limiter\/vendor-prefixed\/nikolaposa\/rate-limit\/src\/Psr16RateLimiter.php(129): BrianHenryIE\\Checkout_Rate_Limiter\\WpOop\\TransientCache\\CachePool->set('checkout\/checko...', Array, 60)\n#2 \/home\/customer\/www\/domain.com\/public_html\/wp-content\/plugins\/bh-wc-checkout-rate-limiter\/vendor-prefixed\/nikolaposa\/rate-limit\/src\/Psr16RateLimiter.php(59): BrianHenryIE\\Checkout_Rate","file":"\/home\/customer\/www\/domain.com\/public_html\/wp-content\/plugins\/bh-wc-checkout-rate-limiter\/vendor-prefixed\/wp-oop\/transient-cache\/src\/CachePool.php","line":140}],"applicationFrame":true,"method":"log","class":"BrianHenryIE\\Checkout_Rate_Limiter\\WP_Logger\\API\\BH_WP_PSR_Logger"},{"file":"\/home\/customer\/www\/domain.com\/public_html\/wp-content\/plugins\/bh-wc-checkout-rate-limiter\/vendor-prefixed\/brianhenryie\/bh-wp-logger\/src\/api\/class-bh-wp-psr-logger.php","lineNumber":52,"arguments":["Uncaught RuntimeException: set_transient() failed with key \"checkout\/checkout74.80.182.73-60\" with TTL 60s in \/home\/customer\/www\/domain.com\/public_html\/wp-content\/plugins\/bh-wc-checkout-rate-limiter\/vendor-prefixed\/wp-oop\/transient-cache\/src\/CachePool.php:322\nStack trace:\n#0 \/home\/customer\/www\/domain.com\/public_html\/wp-content\/plugins\/bh-wc-checkout-rate-limiter\/vendor-prefixed\/wp-oop\/transient-cache\/src\/CachePool.php(137): BrianHenryIE\\Checkout_Rate_Limiter\\WpOop\\TransientCache\\CachePool->setTransient('checkout\/checko...', Array, 60)\n#1 \/home\/customer\/www\/domain.com\/public_html\/wp-content\/plugins\/bh-wc-checkout-rate-limiter\/vendor-prefixed\/nikolaposa\/rate-limit\/src\/Psr16RateLimiter.php(129): BrianHenryIE\\Checkout_Rate_Limiter\\WpOop\\TransientCache\\CachePool->set('checkout\/checko...', Array, 60)\n#2 \/home\/customer\/www\/domain.com\/public_html\/wp-content\/plugins\/bh-wc-checkout-rate-limiter\/vendor-prefixed\/nikolaposa\/rate-limit\/src\/Psr16RateLimiter.php(59): BrianHenryIE\\Checkout_Rate",{"type":1,"message":"Uncaught RuntimeException: set_transient() failed with key \"checkout\/checkout74.80.182.73-60\" with TTL 60s in \/home\/customer\/www\/domain.com\/public_html\/wp-content\/plugins\/bh-wc-checkout-rate-limiter\/vendor-prefixed\/wp-oop\/transient-cache\/src\/CachePool.php:322\nStack trace:\n#0 \/home\/customer\/www\/domain.com\/public_html\/wp-content\/plugins\/bh-wc-checkout-rate-limiter\/vendor-prefixed\/wp-oop\/transient-cache\/src\/CachePool.php(137): BrianHenryIE\\Checkout_Rate_Limiter\\WpOop\\TransientCache\\CachePool->setTransient('checkout\/checko...', Array, 60)\n#1 \/home\/customer\/www\/domain.com\/public_html\/wp-content\/plugins\/bh-wc-checkout-rate-limiter\/vendor-prefixed\/nikolaposa\/rate-limit\/src\/Psr16RateLimiter.php(129): BrianHenryIE\\Checkout_Rate_Limiter\\WpOop\\TransientCache\\CachePool->set('checkout\/checko...', Array, 60)\n#2 \/home\/customer\/www\/domain.com\/public_html\/wp-content\/plugins\/bh-wc-checkout-rate-limiter\/vendor-prefixed\/nikolaposa\/rate-limit\/src\/Psr16RateLimiter.php(59): BrianHenryIE\\Checkout_Rate","file":"\/home\/customer\/www\/domain.com\/public_html\/wp-content\/plugins\/bh-wc-checkout-rate-limiter\/vendor-prefixed\/wp-oop\/transient-cache\/src\/CachePool.php","line":140}],"applicationFrame":true,"method":"error","class":"BrianHenryIE\\Checkout_Rate_Limiter\\WP_Logger\\API\\BH_WP_PSR_Logger"},{"file":"\/home\/customer\/www\/domain.com\/public_html\/wp-content\/plugins\/bh-wc-checkout-rate-limiter\/vendor-prefixed\/brianhenryie\/bh-wp-logger\/src\/php\/class-php-shutdown-handler.php","lineNumber":87,"arguments":[],"applicationFrame":true,"method":"handle","class":"BrianHenryIE\\Checkout_Rate_Limiter\\WP_Logger\\PHP\\PHP_Shutdown_Handler"},{"file":"unknown","lineNumber":0,"arguments":[],"applicationFrame":false,"method":"[top]","class":null}],"filters":["template_redirect","wc_ajax_checkout"]}

Fatal Error on install

Installed this on a client's site after using it on other client sites with no issue. It created a fatal error that may have to do with a conflict with Jetpack:

[11-Oct-2022 02:40:33 UTC] PHP Fatal error: Uncaught TypeError: Argument 3 passed to BrianHenryIE\Checkout_Rate_Limiter\Admin\Plugins_Page::action_links() must be of the type array, null given, called in /chroot/home/server_name_removed/html/wp-includes/class-wp-hook.php on line 307 and defined in /chroot/home/server_name_removed/html/wp-content/plugins/bh-wc-checkout-rate-limiter/Admin/class-plugins-page.php:57 Stack trace: #0 /chroot/home/server_name_removed/html/wp-includes/class-wp-hook.php(307): BrianHenryIE\Checkout_Rate_Limiter\Admin\Plugins_Page->action_links(Array, 'bh-wc-checkout-...', NULL, 'all') #1 /chroot/home/server_name_removed/html/wp-includes/plugin.php(191): WP_Hook->apply_filters(Array, Array) #2 /chroot/home/server_name_removed/html/wp-content/plugins/jetpack/jetpack_vendor/automattic/jetpack-sync/src/modules/class-callables.php(380): apply_filters('plugin_action_l...', Array, 'bh-wc-checkout-...', NULL, 'all') #3 /chroot/home/server_name_removed/html/wp-includes/class-wp- in /chroot/home/server_name_removed/html/wp-content/plugins/bh-wc-checkout-rate-limiter/Admin/class-plugins-page.php on line 57

Fatal error thrown at checkout

Hello!

This looks like a great plugin, thanks for putting in the time to make it.

I've installed on my development environment, however once I click checkout on the checkout page the following fatal error is thrown:

PHP Fatal error:  Declaration of BrianHenryIE\Checkout_Rate_Limiter\WpOop\TransientCache\CachePool::get($key, $default = null) must be compatible with Psr\SimpleCache\CacheInterface::get(string $key, mixed $default = null): mixed in /srv/www/devsite/current/web/app/plugins/bh-wc-checkout-rate-limiter/vendor-prefixed/wp-oop/transient-cache/src/CachePool.php on line 93

Here's the logs

2022-11-23T10:05:23+00:00 DEBUG Checking 192.168.57.1 rate limit 2 per 60 seconds.
{"debug_backtrace":[{"file":"\/srv\/www\/devsite\/current\/web\/app\/plugins\/bh-wc-checkout-rate-limiter\/src\/WooCommerce\/class-ajax.php","lineNumber":78,"arguments":[],"applicationFrame":false,"method":"[top]","class":null}],"filters":["template_redirect","wc_ajax_checkout"]}
2022-11-23T10:05:23+00:00 ERROR Declaration of BrianHenryIE\Checkout_Rate_Limiter\WpOop\TransientCache\CachePool::get($key, $default = null) must be compatible with Psr\SimpleCache\CacheInterface::get(string $key, mixed $default = null): mixed
{"type":64,"message":"Declaration of BrianHenryIE\\Checkout_Rate_Limiter\\WpOop\\TransientCache\\CachePool::get($key, $default = null) must be compatible with Psr\\SimpleCache\\CacheInterface::get(string $key, mixed $default = null): mixed","file":"\/srv\/www\/devsite\/current\/web\/app\/plugins\/bh-wc-checkout-rate-limiter\/vendor-prefixed\/wp-oop\/transient-cache\/src\/CachePool.php","line":93,"debug_backtrace":[{"file":"\/srv\/www\/devsite\/current\/web\/app\/plugins\/bh-wc-checkout-rate-limiter\/vendor-prefixed\/brianhenryie\/bh-wp-logger\/src\/PHP\/class-php-shutdown-handler.php","lineNumber":87,"arguments":[],"applicationFrame":true,"method":"handle","class":"BrianHenryIE\\Checkout_Rate_Limiter\\WP_Logger\\PHP\\PHP_Shutdown_Handler"},{"file":"unknown","lineNumber":0,"arguments":[],"applicationFrame":false,"method":"[top]","class":null}],"filters":["template_redirect","wc_ajax_checkout"]}

Looks like it's due to the difference in some implementations, here's Psr\SimpleCache\CacheInterface:

public function get(string $key, mixed $default = null): mixed;

This is BrianHenryIE\Checkout_Rate_Limiter\WpOop\TransientCache\CachePool

public function get($key, $default = null)

In theory it should be a simple change of definitions.

Env details:
WC Version: 5.8.1
WP Version: 5.9.3
PHP Version: 8.0.17

Logger crashes if unable to write

When attempting to use WP-CLI , the command line crashes because it's unable to write the file.
It would probably need a try/catch or another logging location.

# sudo -u wpcli wp redis flush
PHP Fatal error:  Uncaught RuntimeException: The file could not be written to. Check that appropriate permissions have been set. in /var/www/html/wordpress/web/app/plugins/bh-wc-checkout-rate-limiter/strauss/katzgrau/klogger/src/Logger.php:134
Stack trace:
#0 /var/www/html/wordpress/web/app/plugins/bh-wc-checkout-rate-limiter/strauss/brianhenryie/wp-logger/src/includes/class-bh-wp-logger.php(140): BrianHenryIE\Checkout_Rate_Limiter\Katzgrau\KLogger\Logger->__construct()
#1 /var/www/html/wordpress/web/app/plugins/bh-wc-checkout-rate-limiter/strauss/brianhenryie/wp-logger/src/class-logger.php(23): BrianHenryIE\Checkout_Rate_Limiter\BrianHenryIE\WP_Logger\includes\BH_WP_Logger->__construct()
#2 /var/www/html/wordpress/web/app/plugins/bh-wc-checkout-rate-limiter/strauss/brianhenryie/wp-logger/src/class-logger.php(40): BrianHenryIE\Checkout_Rate_Limiter\BrianHenryIE\WP_Logger\Logger->__construct()
#3 /var/www/html/wordpress/web/app/plugins/bh-wc-checkout-rate-limiter/bh-wc-checkout-rate-limiter.php(64): BrianHenryIE\Checkout_Rate_L in /var/www/html/wordpress/web/app/plugins/bh-wc-checkout-rate-limiter/strauss/katzgrau/klogger/src/Logger.php on line 134

Log file link doesn't update (minor issue)

Bug Report

Yes, I reviewed the contribution guidelines.
Yes, more specifically, I reviewed the guidelines on how to write clear bug reports.

Describe the current, buggy behavior

On the logs page, when the "Log date" dropdown is changed, the text following "Displaying log file at" changes, but the actual file link does not. The link continues to point to the original file that was displayed for the current date.

Describe how other contributors can replicate this bug

Vistit /wp-admin/admin.php?page=bh-wc-checkout-rate-limiter-logs
Note that the log file for today's date is displayed, for example, 2023-11-26
Change the dropdown to a different date, for example 2023-11-24
Note that the text following "Displaying log file at" changes to the file for 11-24
Hover over the file link and note that it still points to the file for 11-26

// You can also use code snippets if needed.

Describe what you would expect as the correct outcome

Update the file link to download the log for the selected date.

Let us know what environment you are running this on

OS:	Linux 5.15.0-89-generic #99-Ubuntu SMP Mon Oct 30 20:42:41 UTC 2023 x86_64
Shell:	/bin/bash
PHP binary:	/usr/bin/php7.4
PHP version:	7.4.33
php.ini used:	/etc/php/7.4/cli/php.ini
MySQL binary:	/usr/bin/mysql
MySQL version:	mysql  Ver 15.1 Distrib 10.6.12-MariaDB, for debian-linux-gnu (x86_64) using  EditLine wrapper
SQL modes:	
WP-CLI root dir:	phar://wp-cli.phar/vendor/wp-cli/wp-cli
WP-CLI vendor dir:	phar://wp-cli.phar/vendor
WP_CLI phar path:	/var/www/html
WP-CLI packages dir:	
WP-CLI global config:	
WP-CLI project config:	
WP-CLI version:	2.5.0

Provide additional context/Screenshots

Add any other context about the problem here.

If applicable, add screenshots to help explain (you can just drag&drop images into the Github issue).

Unknown function error

We keep getting this error on the admin pages:

Checkout Rate Limiter. Error: "Uncaught Error: Call to undefined function BrianHenryIE\Checkout_Rate_Limiter\WooCommerce\wc_get_current_admin_url() in /chroot/home/server_name_removed/html/wp-content/plugins/bh-wc-checkout-rate-limiter/WooCommerce/class-settings-payments.php:59

Stack trace:

#0 /chroot/home/server_name_removed/html/wp-includes/class-wp-hook.php(307): BrianHenryIE\Checkout_Rate_Limiter\WooCommerce\Settings_Payments->record_page_visit_time(Object(WP_Screen))

#1 /chroot/home/server_name_removed/html/wp-includes/class-wp-hook.php(331): WP_Hook->apply_filters(NULL, Array)

#2 /chroot/home/server_name_removed/html/wp-includes/plugin.php(476): WP_Hook->do_action(Array)

#3 /chroot/home/server_name_removed/html/wp-admin/includes/class-wp-screen.php(422): do_action('current_screen', Object(WP_Screen))

#4 /chroot/home/server_name_removed/html/wp-admin/includes/screen.php(243): WP_Screen->set_current_screen()

#5 /chroot/home/server_name_removed/html/wp-content/plugins" at 2022-10-11T03:02:39Z UTC.

Syntax error

Getting the following error when activating the latest version of the plugin:

Parse error: syntax error, unexpected 'Logger_Settings_Interface' (T_STRING), expecting function (T_FUNCTION) or const (T_CONST) in /Users/korymathis/Local Sites/healer/app/public/wp-content/plugins/bh-wc-checkout-rate-limiter/strauss/brianhenryie/wp-logger/src/Includes/class-bh-wp-logger.php on line 38

log into the Order Notes, any blocks from the rate limit plugin

Hey there,

Testing out the plugin and its nice and simple. May I suggest to make the troubleshooting process of failed orders easier that you write into the order notes of the failed order the fact that the rate limit plugin was the one that blocked the order. This way blocked orders that are really false positives can be identified easier by someone providing support.

Plugin causing fatal error

Firstly thank you for this plugin - hugely useful for me to help prevent card testing and it's much appreciated. I'm getting a fatal error on installation...

Warning: require_once(/www/wp-content/plugins/bh-wc-checkout-rate-limiter-1.2.0/vendor-prefixed/autoload.php): failed to open stream: No such file or directory in /www/wp-content/plugins/bh-wc-checkout-rate-limiter-1.2.0/autoload.php on line 39 Fatal error: require_once(): Failed opening required '/www/wp-content/plugins/bh-wc-checkout-rate-limiter-1.2.0/vendor-prefixed/autoload.php' (include_path='.:/usr/share/php') in /www/wp-content/plugins/bh-wc-checkout-rate-limiter-1.2.0/autoload.php on line 39

Not a huge amount of other plugins installed.

PHP: 7.4
Wordpress: 6.02
WooCommerce: 7.0.0

Additional hooks

Thank you for creating this plugin! 🙏

We are using the CheckoutWC plugin and it does not use the wc_ajax_checkout hook, so your rate limiting is not triggered/checked.

We modified your plugin, to use it on our site, but would prefer some additional hooks that we can use and extend its functionality, so we can update your plugin regularly.

Action hook 1:
Here https://github.com/BrianHenryIE/bh-wc-checkout-rate-limiter/blob/master/src/class-bh-wc-checkout-rate-limiter.php#L97, we would need an additional action hook, so we can hook the CheckoutWC ajax hook to your rate limiter. We added this line:
add_action( 'cfw_before_process_checkout', array( $ajax, 'rate_limit_checkout' ), 0 );, so we would need an action hook, like do_action( 'bh_wcr_define_woocommerce_ajax_hooks', $ajax ); in that method.

Action hook2:
Here https://github.com/BrianHenryIE/bh-wc-checkout-rate-limiter/blob/master/src/woocommerce/class-ajax.php#L113, right before the json error response, we would need another action item, because CheckoutWC is expecting a different response, so adding an action hook like this would be awesome: do_action( 'bh_wcr_checkout_rate_limit_exceeded', $rate_limiter );

I'll prepare a quick PR so it will be easier for you, but I don't know which prefix to use for these hooks, because I can see mixed ones being used in the plugin.