Cross-site request forgery (CSRF) vulnerabilities occur when attackers can trick a user to perform sensitive authenticated operations on a web application without his consent.
Imagine a web application where an authenticated user can do actions like changing his email address and which has no CSRF protection. A malicious website could forge a web page form to send the HTTP request that change the user email. When the user visits the malicious web page, the form is automatically submitted in his name and his account email is changed to an arbitrary email.
Such an attack is only possible if the web browser automatically sends authentication information to the trusted domain (e.g cookie based authentication)
There is a risk if you answered yes to any of those questions.
GET which are designed to be
used only for information retrieval. For a Django application, the code is sensitive when,
django.middleware.csrf.CsrfViewMiddleware is not used in the Django settings:
MIDDLEWARE = [
'django.middleware.security.SecurityMiddleware',
'django.contrib.sessions.middleware.SessionMiddleware',
'django.middleware.common.CommonMiddleware',
'django.contrib.auth.middleware.AuthenticationMiddleware',
'django.contrib.messages.middleware.MessageMiddleware',
'django.middleware.clickjacking.XFrameOptionsMiddleware',
] # Sensitive: django.middleware.csrf.CsrfViewMiddleware is missing
@csrf_exempt # Sensitive
def example(request):
return HttpResponse("default")
For a Flask application, the code is sensitive when,
WTF_CSRF_ENABLED setting is set to false: app = Flask(__name__) app.config['WTF_CSRF_ENABLED'] = False # Sensitive
CSRFProtect module:
app = Flask(__name__) # Sensitive: CSRFProtect is missing
@app.route('/')
def hello_world():
return 'Hello, World!'
app = Flask(__name__)
csrf = CSRFProtect()
csrf.init_app(app)
@app.route('/example/', methods=['POST'])
@csrf.exempt # Sensitive
def example():
return 'example '
class unprotectedForm(FlaskForm):
class Meta:
csrf = False # Sensitive
name = TextField('name')
submit = SubmitField('submit')
For a Django application,
django.middleware.csrf.CsrfViewMiddleware:
MIDDLEWARE = [
'django.middleware.security.SecurityMiddleware',
'django.contrib.sessions.middleware.SessionMiddleware',
'django.middleware.common.CommonMiddleware',
'django.middleware.csrf.CsrfViewMiddleware', # Compliant
'django.contrib.auth.middleware.AuthenticationMiddleware',
'django.contrib.messages.middleware.MessageMiddleware',
'django.middleware.clickjacking.XFrameOptionsMiddleware',
]
def example(request): # Compliant
return HttpResponse("default")
For a Flask application,
CSRFProtect module should be used (and not disabled further with WTF_CSRF_ENABLED set to false):
app = Flask(__name__) csrf = CSRFProtect() csrf.init_app(app) # Compliant
@app.route('/example/', methods=['POST']) # Compliant
def example():
return 'example '
class unprotectedForm(FlaskForm):
class Meta:
csrf = True # Compliant
name = TextField('name')
submit = SubmitField('submit')