secure 0.1.5

A lightweight package that adds optional security headers and cookie attributes for Python web frameworks.

Secure

Secure 🔒 is a lightweight package that adds optional security headers and cookie attributes for Python web frameworks.

Supported Python web frameworks:

• Bottle
• CherryPy
• Falcon
• Pyramid
• Responder
• Sanic

Please see flask-talisman for Flask support and django-security for Django support.

Install

pip: pip install secure

pipenv: pipenv install secure

Headers

Server

Contain information about server software
Default Value: NULL (obfuscate server information)

Strict-Transport-Security (HSTS)

Ensure application communication is sent over HTTPS
Default Value: max-age=63072000; includeSubdomains

X-Frame-Options (XFO)

Disable framing from different origins (clickjacking defense)
Default Value: SAMEORIGIN

X-XSS-Protection

Enable browser cross-site scripting filters
Default Value: X-XSS-Protection", "1; mode=block

X-Content-Type-Options

Prevent MIME-sniffing
Default Value: nosniff

Content-Security-Policy (CSP)

Prevent cross-site injections
Default Value: script-src 'self'; object-src 'self' (not included by default)*

Referrer-Policy

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

Cache-control / Pragma

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

*The Content-Security-Policy (CSP) header can break functionality and can (and should) be carefully constructed, use the csp=True option to enable default values.

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

Example

secure.SecureHeaders.framework(response)

Default HTTP response headers:

Server: NULL
Strict-Transport-Security: max-age=63072000; includeSubdomains
X-Frame-Options: SAMEORIGIN
X-XSS-Protection: 1; mode=block
X-Content-Type-Options: nosniff
Referrer-Policy: no-referrer, strict-origin-when-cross-origin
Cache-control: no-cache, no-store, must-revalidate
Pragma: no-cache

Options

You can toggle the setting of headers with default values by passing True or False and override default values by passing a string to the following options:

• server - set the Server header, e.g. Server=“Secure” (string / bool, default=True)
• hsts - set the Strict-Transport-Security header (string / bool, default=True)
• xfo - set the X-Frame-Options header (string / bool, default=True)
• xss - set the X-XSS-Protection header (string / bool, default=True)
• content - set the X-Content-Type-Options header (string / bool, default=True)
• csp - set the Content-Security-Policy (string / bool, default=False) *
• referrer - set the Referrer-Policy header (string / bool, default=True)
• cache - set the Cache-control and Pragma headers (string / bool, default=True)

Example

secure.SecureHeaders.framework(response, hsts=False, csp=True, xfo="DENY")

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.

Example

secure.SecureCookie.framework(response, name="framework", value="ABC123")

Default Set-Cookie HTTP response header:

Set-Cookie: framework=ABC123; Path=/; secure; HttpOnly; SameSite=lax

Options

You can modify default cookie attribute values by passing the following options:

• name - set the cookie name (string, No default value)
• value - set the cookie value (string, No default value)
• path - set the Path attribute, e.g.path=“/secure” (string, default="/")
• secure - set the Secure flag (bool, default=True)
• httponly - set the HttpOnly flag (bool, default=True)
• samesite - set the SameSite attribute, e.g. samesite=“strict” (bool / string, options: "lax", "strict" or False, default="lax")
• expires - set the Expires attribute with the cookie expiration in hours, e.g.expires=1 (number / bool, default=False)

Example

secure.SecureCookie.framework(
        response,
        name="framework",
        value="ABC123",
        samesite=False,
        path="/secure",
        expires=24,
    )

Supported Frameworks

Bottle

Headers

secure.SecureHeaders.bottle(response)

Example

from bottle import route, run, response, hook
from secure import SecureHeaders

. . . 

@hook("after_request")
def set_secure_headers():
    SecureHeaders.bottle(response)

. . . 

Cookies

secure.SecureCookie.bottle(response, name="bottle", value="ABC123")

Example

from bottle import route, run, response, hook
from secure import SecureCookie

. . . 

@route("/secure")
def set_secure_cookie():
    SecureCookie.bottle(response, name="bottle", value="ABC123")
    return "Secure"

. . . 

CherryPy

Headers

'tools.response_headers.headers': secure.SecureHeaders.cherrypy()

Example

CherryPy Application Configuration:

import cherrypy
from secure import SecureHeaders

. . . 

config = {
    '/': {
        'tools.response_headers.on': True,
        'tools.response_headers.headers': SecureHeaders.cherrypy(),
    }
}

. . . 

Cookies

response_headers = cherrypy.response.headers
secure.SecureCookie.cherrypy(response_headers, name="cherrypy", value="ABC123")

Example

import cherrypy
from secure import SecureCookie

. . . 

class SetSecureCookie(object):
    @cherrypy.expose
    def set_secure_cookie(self):
        response_headers = cherrypy.response.headers
        SecureCookie.cherrypy(response_headers, name="cherrypy", value="ABC123")
        return "Secure"

. . . 

Falcon

Headers

secure.SecureHeaders.falcon(resp)

Example

import falcon
from secure import SecureHeaders

. . . 

class SetSecureHeaders(object):
    def process_request(self, req, resp):
        SecureHeaders.falcon(resp)

app = api = falcon.API(middleware=[SetSecureHeaders()])

. . . 

Cookies

secure.SecureCookie.falcon(resp, name="falcon", value="ABC123")

Example

import falcon
from secure import SecureCookie

. . . 

class SetSecureCookie(object):
    def on_get(self, req, resp):
        resp.body = "Secure"
        SecureCookie.falcon(resp, name="falcon", value="ABC123")

. . . 

Pyramid

Headers

Pyramid Tween:

def set_secure_headers(handler, registry):
    def tween(request):
        response = handler(request)
        secure.SecureHeaders.pyramid(response)
        return response

Example

from pyramid.config import Configurator
from pyramid.response import Response
from secure import SecureHeaders

. . . 

def set_secure_headers(handler, registry):
    def tween(request):
        response = handler(request)
        SecureHeaders.pyramid(response)
        return response

    return tween

. . . 

config.add_tween(".set_secure_headers")

. . . 

Cookies

response = Response("Secure")
    secure.SecureCookie.pyramid(response, name="pyramid", value="ABC123")

Example

from pyramid.config import Configurator
from pyramid.response import Response
from secure import SecureCookie

. . . 

def set_secure_cookie(request):
    response = Response("Secure")
    SecureCookie.pyramid(response, name="pyramid", value="ABC123")
    return response

. . . 

Responder

Headers

secure.SecureHeaders.responder(resp)

Example

import responder
from secure import SecureHeaders

api = responder.API()

. . . 

@api.route(before_request=True)
def set_secure_headers(req, resp):
    SecureHeaders.responder(resp)

. . . 

You should use Responder's built in HSTS and pass the hsts=False option.

Cookies

secure.SecureCookie.responder(resp, name="reponder", value="ABC123")

Example

import responder
from secure import SecureCookie

api = responder.API(cors=True)

. . . 

@api.route("/secure")
async def set_secure_cookie(req, resp):
    resp.text = "Secure"
    SecureCookie.responder(resp, name="reponder", value="ABC123")

. . . 

Sanic

Headers

secure.SecureHeaders.sanic(response)

Example

from sanic import Sanic
from secure import SecureHeaders, SecureCookie

app = Sanic()

. . . 

@app.middleware('response')
async def set_secure_headers(request, response):
    SecureHeaders.sanic(response)

. . . 

Cookies

secure.SecureCookie.sanic(response, name="sanic", value="ABC123")

Example

from sanic import Sanic
from sanic.response import text

from secure import SecureHeaders, SecureCookie

app = Sanic()

. . . 

@app.route("/secure")
async def set_secure_cookie(request):
    response = text("Secure")
    SecureCookie.sanic(response, name="sanic", value="ABC123")
    return response

. . . 

To set Cross Origin Resource Sharing (CORS) headers, please see sanic-cors.

Attribution/References

Frameworks

• Bottle - A fast and simple micro-framework for python web-applications.
• CherryPy - A pythonic, object-oriented HTTP framework.
• Falcon - A bare-metal Python web API framework for building high-performance microservices, app backends, and higher-level frameworks.
• Pyramid - A Python web framework
• Sanic - An Async Python 3.5+ web server that's written to go fast
• Responder - A familiar HTTP Service Framework

Resources

• 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