Awesome
Secure Headers ![Build + Test](https://github.com/github/secure_headers/workflows/Build%20+%20Test/badge.svg?branch=main)
main branch represents 6.x line. See the upgrading to 4.x doc, upgrading to 5.x doc, or upgrading to 6.x doc for instructions on how to upgrade. Bug fixes should go in the 5.x branch for now.
The gem will automatically apply several headers that are related to security. This includes:
- Content Security Policy (CSP) - Helps detect/prevent XSS, mixed-content, and other classes of attack. CSP 2 Specification
- HTTP Strict Transport Security (HSTS) - Ensures the browser never visits the http version of a website. Protects from SSLStrip/Firesheep attacks. HSTS Specification
- X-Frame-Options (XFO) - Prevents your content from being framed and potentially clickjacked. X-Frame-Options Specification
- X-XSS-Protection - Cross site scripting heuristic filter for IE/Chrome
- X-Content-Type-Options - Prevent content type sniffing
- X-Download-Options - Prevent file downloads opening
- X-Permitted-Cross-Domain-Policies - Restrict Adobe Flash Player's access to data
- Referrer-Policy - Referrer Policy draft
- Expect-CT - Only use certificates that are present in the certificate transparency logs. Expect-CT draft specification.
- Clear-Site-Data - Clearing browser data for origin. Clear-Site-Data specification.
It can also mark all http cookies with the Secure, HttpOnly and SameSite attributes. This is on default but can be turned off by using config.cookies = SecureHeaders::OPT_OUT
.
secure_headers
is a library with a global config, per request overrides, and rack middleware that enables you customize your application settings.
Documentation
Configuration
If you do not supply a default
configuration, exceptions will be raised. If you would like to use a default configuration (which is fairly locked down), just call SecureHeaders::Configuration.default
without any arguments or block.
All nil
values will fallback to their default values. SecureHeaders::OPT_OUT
will disable the header entirely.
Word of caution: The following is not a default configuration per se. It serves as a sample implementation of the configuration. You should read more about these headers and determine what is appropriate for your requirements.
SecureHeaders::Configuration.default do |config|
config.cookies = {
secure: true, # mark all cookies as "Secure"
httponly: true, # mark all cookies as "HttpOnly"
samesite: {
lax: true # mark all cookies as SameSite=lax
}
}
# Add "; preload" and submit the site to hstspreload.org for best protection.
config.hsts = "max-age=#{1.week.to_i}"
config.x_frame_options = "DENY"
config.x_content_type_options = "nosniff"
config.x_xss_protection = "1; mode=block"
config.x_download_options = "noopen"
config.x_permitted_cross_domain_policies = "none"
config.referrer_policy = %w(origin-when-cross-origin strict-origin-when-cross-origin)
config.csp = {
# "meta" values. these will shape the header, but the values are not included in the header.
preserve_schemes: true, # default: false. Schemes are removed from host sources to save bytes and discourage mixed content.
disable_nonce_backwards_compatibility: true, # default: false. If false, `unsafe-inline` will be added automatically when using nonces. If true, it won't. See #403 for why you'd want this.
# directive values: these values will directly translate into source directives
default_src: %w('none'),
base_uri: %w('self'),
child_src: %w('self'), # if child-src isn't supported, the value for frame-src will be set.
connect_src: %w(wss:),
font_src: %w('self' data:),
form_action: %w('self' github.com),
frame_ancestors: %w('none'),
img_src: %w(mycdn.com data:),
manifest_src: %w('self'),
media_src: %w(utoob.com),
object_src: %w('self'),
sandbox: true, # true and [] will set a maximally restrictive setting
plugin_types: %w(application/x-shockwave-flash),
script_src: %w('self'),
script_src_elem: %w('self'),
script_src_attr: %w('self'),
style_src: %w('unsafe-inline'),
style_src_elem: %w('unsafe-inline'),
style_src_attr: %w('unsafe-inline'),
worker_src: %w('self'),
upgrade_insecure_requests: true, # see https://www.w3.org/TR/upgrade-insecure-requests/
report_uri: %w(https://report-uri.io/example-csp)
}
# This is available only from 3.5.0; use the `report_only: true` setting for 3.4.1 and below.
config.csp_report_only = config.csp.merge({
img_src: %w(somewhereelse.com),
report_uri: %w(https://report-uri.io/example-csp-report-only)
})
end
Deprecated Configuration Values
block_all_mixed_content
- this value is deprecated in favor ofupgrade_insecure_requests
. See https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Content-Security-Policy/block-all-mixed-content for more information.
Default values
All headers except for PublicKeyPins and ClearSiteData have a default value. The default set of headers is:
Content-Security-Policy: default-src 'self' https:; font-src 'self' https: data:; img-src 'self' https: data:; object-src 'none'; script-src https:; style-src 'self' https: 'unsafe-inline'
Strict-Transport-Security: max-age=631138519
X-Content-Type-Options: nosniff
X-Download-Options: noopen
X-Frame-Options: sameorigin
X-Permitted-Cross-Domain-Policies: none
X-Xss-Protection: 0
API configurations
Which headers you decide to use for API responses is entirely a personal choice. Things like X-Frame-Options seem to have no place in an API response and would be wasting bytes. While this is true, browsers can do funky things with non-html responses. At the minimum, we suggest CSP:
SecureHeaders::Configuration.override(:api) do |config|
config.csp = { default_src: 'none' }
config.hsts = SecureHeaders::OPT_OUT
config.x_frame_options = SecureHeaders::OPT_OUT
config.x_content_type_options = SecureHeaders::OPT_OUT
config.x_xss_protection = SecureHeaders::OPT_OUT
config.x_permitted_cross_domain_policies = SecureHeaders::OPT_OUT
end
However, I would consider these headers anyways depending on your load and bandwidth requirements.
Acknowledgements
This project originated within the Security team at Twitter. An archived fork from the point of transition is here: https://github.com/twitter-archive/secure_headers.
Contributors include:
- Neil Matatall @oreoshake
- Chris Aniszczyk
- Artur Dryomov
- Bjørn Mæland
- Arthur Chiu
- Jonathan Viney
- Jeffrey Horn
- David Collazo
- Brendon Murphy
- William Makley
- Reed Loden
- Noah Kantrowitz
- Wyatt Anderson
- Salimane Adjao Moustapha
- Francois Chagnon
- Jeff Hodges
- Ian Melven
- Darío Javier Cravero
- Logan Hasson
- Raul E Rangel
- Steve Agalloco
- Nate Collings
- Josh Kalderimis
- Alex Kwiatkowski
- Julich Mera
- Jesse Storimer
- Tom Daniels
- Kolja Dummann
- Jean-Philippe Doyle
- Blake Hitchcock
- vanderhoorn
- orthographic-pedant
- Narsimham Chelluri
If you've made a contribution and see your name missing from the list, make a PR and add it!
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