How to block Yokoy Group Webhooks
Operated by Yokoy Group AG. Yokoy is a spend management SAAS solution. Webhooks generate requests to book expenses or invoices to customer's ERP system whenever the processing and approval process has been completed in Yokoy.
How it identifies itself
YokoyGroupAG/1.0
nginx
In the server block, then reload.
# In the server block. 403 rather than 444: a closed connection tells the
# operator nothing, and an agent that gets a status code can log it.
if ($http_user_agent ~* "(YokoyGroupAG/)") {
return 403;
}
Apache
In .htaccess or the vhost.
BrowserMatchNoCase "YokoyGroupAG/" bad_bot
<RequireAll>
Require all granted
Require not env bad_bot
</RequireAll>
Cloudflare
Security → WAF → Custom rules.
# Security → WAF → Custom rules, action: Block (http.user_agent contains "YokoyGroupAG/")
WordPress
A child theme's functions.php, or a small plugin.
// functions.php of a child theme, or a small plugin. Runs before WordPress
// builds the page, so a blocked agent costs one PHP process and no queries.
add_action('init', function () {
$agent = $_SERVER['HTTP_USER_AGENT'] ?? '';
foreach (['YokoyGroupAG/'] as $needle) {
if (stripos($agent, $needle) !== false) {
status_header(403);
exit('Blocked: Yokoy Group Webhooks');
}
}
});
A rule on the user agent is a rule on a string it chose
The server rules match on a header the requester sets, which stops the agent that says who it is and not the one that copies somebody else's name. Botscope verifies identity against DNS and published address ranges, records which check decided each request, and shows you the ones that lied.