When a domain owner follows the recommendations in this article and sets an HSTS policy on its base domain with includeSubDomains and preload, the domain owner is saying “Every part of our web infrastructure is HTTPS, and always will be.” - and is giving browsers permission to vigorously enforce that from then onwards. However, it’s also highly valuable as an organizational forcing function and compliance mechanism. Strict Transport Security provides meaningful security benefits to visitors, especially visitors on hostile networks. Until that time, the HSTS preload list is a simple, effective mechanism for locking down HTTPS for an entire domain. In the long term, as the web transitions fully to HTTPS and browsers can start phasing out plain HTTP and defaulting to HTTPS, the HSTS preload list (and HSTS itself) may eventually become unnecessary. The website redirects from HTTP to HTTPS, at least on the root domain.Īn example of a valid HSTS header for preloading:.The HSTS policy includes all subdomains, with a long max-age, and a preload flag to indicate that the domain owner consents to preloading.HTTPS is enabled on the root domain (e.g.The Chrome security team allows anyone to submit their domain to the list, provided it meets the following requirements: To solve this problem, the Chrome security team created an “HSTS preload list”: a list of domains baked into Chrome that get Strict Transport Security enabled automatically, even for the first visit.įirefox, Safari, Opera, and Edge also incorporate Chrome’s HSTS preload list, making this feature shared across major browsers. In either case, is never visited, meaning connecting clients will never see an HSTS policy with an includeSubDomains directive that applies to the whole zone. Many federal domains that are used solely for redirects will redirect from directly to.Many federal websites redirect directly from to.In addition, in many cases, there may never be a first visit to. This means that users are not protected until after their first successful secure connection to a given domain. HSTS Preloadingįor a user to take advantage of HSTS, their browser does have to see the HSTS header at least once. The policy is refreshed every time browser sees the header again, so if a user visits at least once every year, they’ll be indefinitely protected by HSTS. In the above example, the browser will remember the HSTS policy for 1 year. While HSTS is in effect, clicking any links to will cause the browser to issue a request directly for. Strict-Transport-Security: max-age=31536000 includeSubdomains preload A user’s network may be hostile and actively rewrite links to Websites that prefer HTTPS will generally still listen for connections over HTTP in order to redirect the user to the HTTPS URL.A user may click on an old link that mistakenly uses an URL.When a user types “gsa.gov” into the URL bar, browsers default to using.The basic problem that HSTS solves is that even after a website turns on HTTPS, visitors may still end up trying to connect over plain HTTP. It was quickly adopted by several major web browsers, and finalized as RFC 6797 in 2012. Strict Transport Security was proposed in 2009, motivated by Moxie Marlinspike’s demonstration of how a hostile network could downgrade visitor connections and exploit insecure redirects.
See below for examples of how to set an HSTS policy in common web servers. (They do not have to each have their own HSTS policy.) All subdomains associated with the parent domain must support HTTPS.The policy should be deployed at, not.Strict-Transport-Security: max-age=31536000 includeSubDomains preload