This is in all likelyhood &quot;Safebrowsing by Google&quot;, which is a default service to run sites you visit past the servers of said company.<p><a href="https:&#x2F;&#x2F;www.google.com&#x2F;transparencyreport&#x2F;safebrowsing&#x2F;diagnostic" rel="nofollow">https:&#x2F;&#x2F;www.google.com&#x2F;transparencyreport&#x2F;safebrowsing&#x2F;diagn...</a><p>That would make you one of the 600 million people using that service, whether you realise it or not.<p>Alas, other  browsers use it too without any warning, although you can turn it off it is not easily discoverable:<p><a href="https:&#x2F;&#x2F;bugzilla.mozilla.org&#x2F;show_bug.cgi?id=430741" rel="nofollow">https:&#x2F;&#x2F;bugzilla.mozilla.org&#x2F;show_bug.cgi?id=430741</a><p>As suggested, add sb.google.com or whatever endpoint is used to &#x2F;etc&#x2F;hosts or HOSTS file.