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How can python / flask block foreign form injections?
Consider the following mwe:
app.py
from flask import Flask, request, render template
app = Flask(__name__)
@app.route('/', methods=['GET','POST'])
def helloworld():
if request.method == 'GET':
return render_template('index.html')
if request.method == 'POST':
print(request.form['info'])
## do something with the info, like write to a database
return 'nothing'
if __name__ == '__main__':
app.run(debug=True)
templates/index.html
<html>
<head>
<script src="//ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js"></script>
<script type='text/javascript' src="{{ url_for('static', filename='js/fire.js') }}"></script>
</head>
<body>
<p>Hello world!</p>
</body>
</html>
static/js/fire.js
$(document).click(function() {
// post data to flask
$.post('/', {'info': 'test'});
return false;
};
My questions are:
Here is a very basic script that can be used to test injections against the above flask application. The accepted answer blocks this script:
<!DOCTYPE html>
<html>
<body>
<h2>Malicious Form Injection</h2>
<form action='http://127.0.0.1:5000/' method='post'>
Input 1:<br>
<input name="info" value="mal1"><br>
<input type="submit" value="Submit">
</form>
</body>
</html>
976
from flask import Flask, request, render template
from flask_wtf.csrf import CSRFProtect
app = Flask(__name__)
CSRFProtect(app)
app.config['SECRET_KEY'] = 'somethignrandom'
@app.route('/', methods=['GET','POST'])
def helloworld():
if request.method == 'GET':
return render_template('index.html')
if request.method == 'POST': # anything post will autocheck csrf
print(request.form['info'])
## do something with the info, like write to a database
return 'nothing'
if __name__ == '__main__':
app.run(debug=True)
There is no need to pass the secret key to the html template, as CSRFProtect will automatically pass the secret key.
<html>
<head>
<script src="//ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js"></script>
<meta name='csrf-token' content="{{ csrf_token() }}">
<script type='text/javascript' src="{{ url_for('static', filename='js/fire.js') }}"></script>
</head>
<body>
<p>Hello world!</p>
</body>
</html>
$(document).click(function() {
// post data to flask
$.post('/', {'info': 'test', '_csrf_token':$('meta[name="csrf-token"]').attr('content')});
return false;
};
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