Flask-Mitten 0.2.1

What is Flask-Mitten?

Adds security functions to Flask applications for preventing some of the basic threats.

Features

Flask-Mitten supports Flask applications to prevent following threats.

• Clickjacking
• CSRF
• Information disclosure through banner grabbing
• JSON hijacking
• Session fixation

It bundles functions of following Flask extensions.

• Flask-KVSession
• flask-csrf

More details, see the implementation.

Usage

Installation

Install the extension with the following commands:

pip install Flask-Mitten

Configuration

Apply the extention to your app:

from flaskext.mitten import Mitten
app = Flask(__name__)
mitten = Mitten(app)

Request headers are overridden to prevent clickjacking and information disclosure.

If you want to set your own banner, you can do it:

mitten.banner = "My Nice Banner!"

Preventing Session Fixation

After login, call a regenerate method of session object:

session.regenerate()

The session ID is regenerated, and it prevents session fixation.

To discard a session, call a destroy method:

session.destroy()

Preventing CSRF

To embed CSRF token, add following line to your template:

<input type="hidden" name="_csrf_token" value="{{ csrf_token() }}" />

A POST request is protected against CSRF automatically.

If you want to exclude a route from CSRF protection, use a csrf_exempt decorator:

@mitten.csrf_exempt
@app.route('/public_api/', methods=['POST'])
def public_api():
    return "result", 200

Preventing JSON Hijacking

If you send a JSON response, you could use a json decorator to avoid JSON hijacking or rendering JSON responses by direct browsing:

@mitten.json
@app.route('/json_api/')
def json_api():
    return jsonify(result='success')

More

For more details, see an example app.