halvarfraudcheck.php

<?php
if (!defined("WHMCS")) {
    die("This file cannot be accessed directly");
}

add_hook( 'ShoppingCartValidateDomain', 1, function ( $vars ) {
    
    if ( $vars['domainoption'] != 'register') {
        return [];
    }
    
    $domain = $vars['sld'].$vars['tld'];
    
    if( !$domain ) {
        return [];
    }

    // Do your magic
    $regexPattern = '';

    // Check if the domain matches the fraudulent pattern
    if( preg_match( $regexPattern, $domain ) ) {
        // Return a fraud message; this prevents the order from proceeding
        return [
            'domain' => 'The domain matches a fraudulent pattern and cannot be registered.',
        ];
    }

    // If no fraud detected, return nothing
    return [];
});