Difference between revisions of "HTTP Strict Transport Security"

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(Change made re: implementation in IIS after seeking approval from the original page author Michael Coates.)
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#REDIRECT [[HTTP_Strict_Transport_Security_Cheat_Sheet]]
== Description ==
HTTP Strict Transport Security (HSTS) is an opt-in security enhancement that is specified by a web application through the use of a special response header. Once a supported browser receives this header that browser will prevent any communications from being sent over HTTP to the specified domain and will instead send all communications over HTTPS. It also prevents HTTPS click through prompts on browsers.
== Examples  ==
Example of the HTTP strict transport security header
  Strict-Transport-Security: max-age=60000
If all subdomains are HTTPS to then the following header is applicable:
  Strict-Transport-Security: max-age=60000; includeSubDomains
== Browser Support ==
{| width="400" cellspacing="1" cellpadding="1" border="1"
| '''Browser'''<br>
| '''Support Introduced'''<br>
| Internet Explorer <br>
| no support as of IE 10 (tested on 2013-01-01)<br>
| Firefox<br>
| 4<br>
| Opera<br>
| 12<br>
| Safari<br>
| ??<br>
| Chrome<br>
== Server Side ==
The web server side needs to inject the HSTS header.
For HTTP sites on the same domain it is [http://tools.ietf.org/html/draft-ietf-websec-strict-transport-sec#section-6.1 not recommended] to add a HSTS header but to do a permanent redirect (301 status code) to the HTTPS site.
An Apache HTTPd example that will permanently redirect a URL to the identical URL with a HTTPS scheme, is as follows:
<VirtualHost *:80>
        ServerAlias *
        RewriteEngine On
        RewriteRule ^(.*)$ https://%{HTTP_HOST}$1 [redirect=301]
On the HTTPS site configuration the following is needed to add the header as [http://tools.ietf.org/html/draft-ietf-websec-strict-transport-sec#section-6.1 recommended by the standard]:
        Header set Strict-Transport-Security "max-age=16070400; includeSubDomains"
The following links show how to do set response headers in other web servers:
* [http://wiki.nginx.org/HttpHeadersModule NGINX]
* [http://redmine.lighttpd.net/wiki/lighttpd/Docs:ModSetEnv#Options Lighttpd]
* [http://httpd.apache.org/docs/2.2/mod/mod_headers.html HTTPd]
==== IIS ====
Whilst [http://technet.microsoft.com/en-us/library/cc753133(WS.10).aspx custom headers] can be configured in IIS without any extensions, it is not possible to restrict these headers to secure transport channels [http://tools.ietf.org/html/rfc6797#section-7.2 as per the HSTS specification]. HSTS has been implemented as per the specification as an [http://hstsiis.codeplex.com/ open source IIS module].
== Threats ==
HSTS addresses the following threats:
* User bookmarks or manually types http://example.com and is subject to a man-in-the-middle attacker
** HSTS automatically upgrades HTTP requests to HTTPS for the target domain
* Web application that is intended to be purely HTTPS inadvertently contains HTTP links or serves content over HTTP
** HSTS automatically upgrades HTTP requests to HTTPS for the target domain
* A man-in-the-middle attacker attempts to intercept traffic from a victim user using an invalid certificate and hopes the user will accept the bad certificate
** HSTS does not allow a user to override the invalid certificate message
== Links ==
[http://dev.chromium.org/sts Chromium Projects/HSTS]
[http://tools.ietf.org/html/draft-ietf-websec-strict-transport-sec HSTS Spec]
[http://en.wikipedia.org/wiki/HTTP_Strict_Transport_Security Wikipedia]
[https://developer.mozilla.org/en/Security/HTTP_Strict_Transport_Security Mozilla Developer Network]
[https://www.owasp.org/index.php/Transport_Layer_Protection_Cheat_Sheet OWASP TLS Protection Cheat Sheet]
[https://developer.mozilla.org/en/Security/HTTP_Strict_Transport_Security Firefox STS Support]
[http://lists.w3.org/Archives/Public/public-webapps/2009JulSep/1148.html Google Chrome STS Support]

Latest revision as of 02:01, 8 July 2016