secure 0.1.2

A small library that adds optional security headers and cookie presets for Responder

Secure

Secure 🔒 is a small library that adds optional security headers and cookie attributes for Responder.

Install

pipenv install secure

Headers

Strict-Transport-Security (HSTS)

Ensure application is loaded over HTTPS
Value: max-age=63072000; includeSubdomains

X-Frame-Options

Disable iframes (Clickjacking protection)
Value: DENY

X-XSS-Protection

Enable Cross-Site Scripting filters
Value: X-XSS-Protection", "1; mode=block

X-Content-Type-Options

Prevent MIME-sniffing
Value: nosniff

Content-Security-Policy (CSP)

Prevent Cross-site injections
Value: script-src 'self'; object-src 'self'

Referrer-Policy

Enable full referrer if same origin, remove path for cross origin and disable referrer in unsupported browsers
Value: no-referrer, strict-origin-when-cross-origin

Cache-control / Pragma

Prevent cacheable HTTPS response
Value: no-cache, no-store / no-cache

Recommendations used by Secure 🔒 and more information regarding security headers can be found at the OWASP Secure Headers Project.

Cookies

Path

The Path directive instructs the browser to only send the cookie if provided path exists in the URL.

Secure

The Secure flag instructs the browser to only send the cookie via HTTPS.

HttpOnly

The HttpOnly flag instructs the browser to not allow any client side code to access the cookie's contents.

SameSite

The SameSite flag directs the browser not to include cookies on certain cross-site requests. There are two values that can be set for the same-site attribute, lax or strict. The lax value allows the cookie to be sent via certain cross-site GET requests, but disallows the cookie on all POST requests. For example cookies are still sent on links <a href=“x”>, prerendering <link rel=“prerender” href=“x” and forms sent by GET requests <form-method=“get”..., but cookies will not be sent via POST requests <form-method=“post”..., images <img src=“x”> or iframes <iframe src=“x”>. The strict value prevents the cookie from being sent cross-site in any context. Strict offers greater security but may impede functionality. This approach makes authenticated CSRF attacks impossible with the strict flag and only possible via state changing GET requests with the lax flag.

Expires

The Expires attribute sets an expiration date for persistent cookies.

Responder Headers

Usage

import responder
import secure

api = responder.API()

... 

@api.route(before_request=True)
def prepare_response(req, resp):
    secure.responder_headers(req, resp)

HTTP response headers:

x-frame-options: DENY
x-xss-protection: 1; mode=block
x-content-type-options: nosniff
referrer-policy: no-referrer, strict-origin-when-cross-origin

Options

Example: secure.responder_headers(req, resp, csp=True)

• hsts - (default=False) *
• frame - (default=True)
• xss - (default=True)
• content - (default=True)
• csp - (default=False) *
• referrer - (default=True)
• cache - (default=False)

You should use Responder's built in HSTS option and the CSP headers should be carefully constructed, however you can use the defaults by including the hsts=True and/or csp=True options.

Responder Cookies

Usage

import responder
import secure

api = responder.API()

... 

@api.route("/secure")
async def greet_world(req, resp):
    resp.text = "Secure"
    secure.responder_cookies(req, resp, name="responder", value="ABC123", expires=1)

Set-Cookie HTTP response header:

set-cookie: responder=ABC123; Path=/; Secure; HttpOnly; SameSite=Lax; Expires=Tue, 27 Nov 2018 11:38:56 GMT;

Options

Example:

secure.responder_cookies(req,resp, name="responder-cookie", value="ABC123", secure=False)

• path -(default="/")
• secure - (default=True)
• httponly - (default=True)
• samesite - options: lax or strict (default="lax")
• expires - cookie expiration in hours (default=False)

Attribution/References

• Responder: A familiar HTTP Service Framework
• kennethreitz/setup.py: 📦 A Human’s Ultimate Guide to setup.py.
• OWASP - Application Security FAQ - Browser Cache
• OWASP - HttpOnly
• OWASP - SameSite
• OWASP - Secure Headers Project
• OWASP - SecureFlag
• OWASP - Session Management Cheat Sheet
• Mozilla Web Security