Python 3.7.5 : Django security issues - part 003.

Let's update this subject today with another new tutorial.
In the last tutorial about Django security I wrote about python package named django-axes.
First, let's fix an old issue about a URL pattern that matches anything and expects an integer that generates errors like:

...
  File "/home/mythcat/.local/lib/python3.7/site-packages/django/db/models/fields/__init__.py", line 1772, 
in get_prep_value
    ) from e
ValueError: Field 'id' expected a number but got 'favicon.ico'.
[22/Jan/2020 21:50:06] "GET /favicon.ico/ HTTP/1.1" 500 130547

Now, let's start my project:

[mythcat@desk ~]$ cd projects/
[mythcat@desk projects]$ cd django/
[mythcat@desk django]$ source env/bin/activate

Create a new folder named static in the test001 folder and add a icon file named favicon.ico.

(env) [mythcat@desk django]$ cd mysite/test001/
(env) [mythcat@desk test001]$ mkdir static 

In the settings.py file you need to have this source code:

STATIC_URL = '/static/'

STATICFILES_DIRS = [
    os.path.join(BASE_DIR, "static"),
]

Change in the urls.py this line of source code to fix the error:

path('<int:author_id>/',views.index_next, name = 'index_next'),

Let's run the Django project server with:

(env) [mythcat@desk django]$ cd mysite/
(env) [mythcat@desk mysite]$ python3 manage.py runserver

I login into my admin area with user catalin and password adminadmin.
If you try to login with a bad password then the account is locked by django-axes python package.
Use this command to reset all lockouts and access records.

(env) [mythcat@desk mysite]$ python3 manage.py axes_reset
No attempts found.

Into admin area you can see the AXES area with Access attempts and Access logs.
Axes listens to the following signals from django.contrib.auth.signals to log access attempts.
In this case Axes lockout responses on failed user authentication attempts from login views.
The Access logs shows access log, see examples:

Jan. 22, 2020, 8:46 p.m.	-	127.0.0.1	catalin	Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/79.0.3945.130 Safari/537.36	/admin/login/
Jan. 21, 2020, 6:42 p.m.	Jan. 22, 2020, 8:45 p.m.	127.0.0.1	catalin	Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/79.0.3945.130 Safari/537.36	/admin/login/

You can set the axes into settings.py file , see this link.

Python 3.7.5 : Use Django Formsets.

Django Formsets manage the complexity of multiple copies of a form in a view.
This simplifies the task of creating a formset for a form that handles multiple instances of a model.
Let's start with my old project:

[mythcat@desk ~]$ cd projects/
[mythcat@desk projects]$ cd django/
[mythcat@desk django]$ source env/bin/activate

Into models.py I add these classes:

#create Inline Form with book and author
class Author(models.Model):
    author_book = models.CharField(max_length = 100)
    def __str__(self):
        return self.author_book

class Book(models.Model):
    book_name = models.CharField(max_length = 100)
    author_book_name = models.ForeignKey(Author,on_delete=models.CASCADE)
    def __str__(self):
        return self.book_name

(env) [mythcat@desk mysite]$ python3 manage.py makemigrations
Migrations for 'test001':
  test001/migrations/0004_author_book.py
    - Create model Author
    - Create model Book
(env) [mythcat@desk mysite]$ python3 manage.py migrate
Operations to perform:
  Apply all migrations: admin, auth, axes, contenttypes, sessions, test001
Running migrations:
  Applying test001.0004_author_book... OK

Add the classes to admin.py:

from .models import Author, Book
...
admin.site.register(Author)
admin.site.register(Book)

Now you can log in into the admin area and add authors and then add books.

Add the source code to views.py:

...
# add to views.py Author and Book 
from .models import Author, Book
# Author , Book redirect 
from django.shortcuts import redirect
...
# author and book source code 
def index_next(request, author_id):
    author = Author.objects.get(pk=author_id)
    BookFormset = inlineformset_factory(Author,Book, fields=('book_name',))
    if request.method == 'POST':
        formset = BookFormset(request.POST,instance = author)
        if formset.is_valid():
            formset.save()
            return redirect('index_next',author_id = author_id)
    formset = BookFormset(instance = author)
    return render(request, 'index_next.html', {'formset': formset})
...

Let's fix the URL for the next step.
Add the source code to urls.py:

...
# add index_next to urls.py 
from test001.views import index_next
...
urlpatterns = [
    ...
    path('&lt author_id &gt',views.index_next, name = 'index_next'),
    ...
    ]

Add index_next.html file into the template folder and into this file write HTML5 with a form and one submit button.
In the form tag add this:

{{ formset.as_p }}

Run the runserver command:

(env) [mythcat@desk mysite]$ python3 manage.py runserver

Use this http://127.0.0.1:8000/1 to see the first on the database shown on the browser.
You can customize the output of inline form, see source code:

...
BookFormset = inlineformset_factory(Author,Book, fields=('book_name',), can_delete=False, extra=1)
...

See the full project on my GitHub account at django_chart project repo.

Python 3.7.5 : Django security issues - part 002.

The project can be found at this Github project.
Let's start with my default project and activate the env:

[mythcat@desk ~]$ cd projects/
[mythcat@desk projects]$ cd django/
[mythcat@desk django]$ source env/bin/activate

Let's install this python module:

(env) [mythcat@desk django]$ pip3 install django-axes --user

Make these changes into settings.py:

(env) [mythcat@desk django]$ cd mysite/
(env) [mythcat@desk mysite]$ ls
db.sqlite3  manage.py  mysite  test001
(env) [mythcat@desk mysite]$ cd mysite/
(env) [mythcat@desk mysite]$ vim settings.py 

Into your settings.py add axes:

INSTALLED_APPS = [
    'django.contrib.admin',
    'django.contrib.auth',
    'django.contrib.contenttypes',
    'django.contrib.sessions',
    'django.contrib.messages',
    'django.contrib.staticfiles',
    'test001',
    'rest_framework',
    'axes'
] 

Add this source code in settings.py:

AUTHENTICATION_BACKENDS = [
    # AxesBackend should be the first backend in the AUTHENTICATION_BACKENDS list.
    'axes.backends.AxesBackend',

    # Django ModelBackend is the default authentication backend.
    'django.contrib.auth.backends.ModelBackend',
] 

Add axes.middleware.AxesMiddleware into MIDDLEWARE area:

MIDDLEWARE = [
    'django.middleware.security.SecurityMiddleware',
    'django.contrib.sessions.middleware.SessionMiddleware',
    'django.middleware.common.CommonMiddleware',
    'django.middleware.csrf.CsrfViewMiddleware',
    'django.contrib.auth.middleware.AuthenticationMiddleware',
    'django.contrib.messages.middleware.MessageMiddleware',
    'django.middleware.clickjacking.XFrameOptionsMiddleware',
    'axes.middleware.AxesMiddleware',
] 

Check the configuration with this command:

(env) [mythcat@desk mysite]$ cd ..
(env) [mythcat@desk mysite]$ python manage.py check
System check identified no issues (0 silenced).

Use this command to sync the database:

(env) [mythcat@desk mysite]$ python manage.py migrate
Operations to perform:
  Apply all migrations: admin, auth, axes, contenttypes, sessions, test001
Running migrations:
  Applying axes.0001_initial... OK
  Applying axes.0002_auto_20151217_2044... OK
  Applying axes.0003_auto_20160322_0929... OK
  Applying axes.0004_auto_20181024_1538... OK
  Applying axes.0005_remove_accessattempt_trusted... OK
  Applying axes.0006_remove_accesslog_trusted... OK

Once Axes is is installed and configured, you can login and logout of your application via the django.contrib.auth views.
This python package can be integrated with some popular 3rd party packages such as Django Allauth, Django REST Framework, and other tools.
I will come with additional information about this python package in the future.

Python 3.7.5 : Django security issues - part 001.

Django like any website development and framework implementation requires security settings and configurations.
Today I will present some aspects of this topic and then I will come back with other information.
1. First, check your security vulnerabilities by the following command:

[mythcat@desk django]$ source env/bin/activate
(env) [mythcat@desk django]$ cd mysite
(env) [mythcat@desk mysite]$ python3 manage.py check --deploy
...
  File "/home/mythcat/projects/django/mysite/mysite/settings.py", line 14
    <<<<<<< HEAD
     

This shows us the bad changes in source code, is added by GitHub features.
Let's run it again:

(env) [mythcat@desk mysite]$ python3 manage.py check --deploy
System check identified some issues:

WARNINGS:
?: (security.W004) You have not set a value for the SECURE_HSTS_SECONDS setting. 

If your entire site is served only over SSL, you may want to consider setting a value and 

enabling HTTP Strict Transport Security. Be sure to read the documentation first; enabling

 HSTS carelessly can cause serious, irreversible problems.
?: (security.W008) Your SECURE_SSL_REDIRECT setting is not set to True. Unless your site 

should be available over both SSL and non-SSL connections, you may want to either set this 

setting True or configure a load balancer or reverse-proxy server to redirect all connections to HTTPS.
?: (security.W012) SESSION_COOKIE_SECURE is not set to True. Using a secure-only session cookie makes 

it more difficult for network traffic sniffers to hijack user sessions.
?: (security.W016) You have 'django.middleware.csrf.CsrfViewMiddleware' in your MIDDLEWARE, but you have

 not set CSRF_COOKIE_SECURE to True. Using a secure-only CSRF cookie makes it more difficult for network

 traffic sniffers to steal the CSRF token.
?: (security.W018) You should not have DEBUG set to True in deployment.
?: (security.W020) ALLOWED_HOSTS must not be empty in deployment.
?: (security.W022) You have not set the SECURE_REFERRER_POLICY setting. Without this, your site 

will not send a Referrer-Policy header. You should consider enabling this header to protect user privacy.

System check identified 7 issues (0 silenced).

This output show us the security warnning problems.
2. Use the Observatory by Mozilla site to scan the security status of your Django website.
3. Django has built-in security against most forms of CSRF threats, but The CSRF protection cannot protect against man-in-the-middle attacks.
Use HTTPS with HTTP Strict Transport Security by add these lines in your settings.py file.

CSRF_COOKIE_SECURE = True #to avoid transmitting the CSRF cookie over HTTP accidentally.
SESSION_COOKIE_SECURE = True #to avoid transmitting the session cookie over HTTP accidentally.

4. A Cross-site Scripting (XSS) allows an attacker to inject a script into the content of a website or application.
In your settings.py use this:

django.middleware.security.SecurityMiddleware
...
SECURE_BROWSER_XSS_FILTER = True
SECURE_CONTENT_TYPE_NOSNIFF = True

5. You can create fake admin login page using django-admin-honeypot to attempt unauthorized access.
6. Use SSL Redirect on your settings.py file.

SECURE_SSL_REDIRECT = True

7. Add Content Security Policy (CSP) to your Django website with the installed django-csp, add following lines to your settings.py file:

# Content Security Policy
CSP_DEFAULT_SRC = ("'none'", )
CSP_STYLE_SRC = ("'self'", )
CSP_SCRIPT_SRC = ("'self'", )
CSP_IMG_SRC = ("'self'", )
CSP_FONT_SRC = ("'self'", )
# Google Tag Manager or Google Analytics should be allowed in your CSP policy. 
CSP_DEFAULT_SRC = ("'none'", )
CSP_STYLE_SRC = ("'self'", "fonts.googleapis.com", "'sha256-/3kWSXHts8LrwfemLzY9W0tOv5I4eLIhrf0pT8cU0WI='")
CSP_SCRIPT_SRC = ("'self'", "ajax.googleapis.com", "www.googletagmanager.com", "www.google-analytics.com")
CSP_IMG_SRC = ("'self'", "data:", "www.googletagmanager.com", "www.google-analytics.com")
CSP_FONT_SRC = ("'self'", "fonts.gstatic.com")
CSP_CONNECT_SRC = ("'self'", )
CSP_OBJECT_SRC = ("'none'", )
CSP_BASE_URI = ("'none'", )
CSP_FRAME_ANCESTORS = ("'none'", )
CSP_FORM_ACTION = ("'self'", )
CSP_INCLUDE_NONCE_IN = ('script-src',)

The HTTP Strict Transport Security can be set into your settings.py file:

SECURE_HSTS_SECONDS = 86400  # 1 day
SECURE_HSTS_INCLUDE_SUBDOMAINS = True
SECURE_HSTS_PRELOAD = True

8. Use records login attempts to your Django powered site and prevents attackers from brute forcing using the django-axes.
This tutorial solves most of the security issues of any website built with Django and not just related to this framework.

Python 3.7.5 : About asterisk operators in Python.

The asterisk known as the star operator is used in Python with more than one meaning attached to it.
Today I will show you some simple examples of how can be used.
Let's start with these issues.
You can merge two or more dictionaries by unpacking them in a new one:

>>> a = {'u': 1}
>>> b = {'v': 2}
>>> ab = {**a, **b, 'c':'d'}
>>> ab
{'u': 1, 'v': 2, 'c': 'd'}

Create multiple assignments:

>>> *x, y = 1, 2, 3, 4
>>> x
[1, 2, 3]

You can split into lists and generate sets:

>>> *a, = "Python"
>>> a
['P', 'y', 't', 'h', 'o', 'n']
>>> print(a)
['P', 'y', 't', 'h', 'o', 'n']
>>> *a,
('P', 'y', 't', 'h', 'o', 'n')
>>> zeros = (0,) * 8
>>> print(zeros)
(0, 0, 0, 0, 0, 0, 0, 0)

For numeric data types is used as multiplication operator:

>>> 2 * 3
6

You can use in mathematical function as an exponent:

>>> 3**2
9

You can create a sequences of strings using it like a repetition operator:

>>> t = 'Bye!'
>>> t * 4 
'Bye!Bye!Bye!Bye!'
>>> p = [0,1]
>>> p * 4 
[0, 1, 0, 1, 0, 1, 0, 1]
>>> r = (0,1)
>>> r * 4
(0, 1, 0, 1, 0, 1, 0, 1)

You can used into definition with arguments: *args and **kwargs:

def set_zero(*args):
    result = 0

The *args will give you all function parameters as a tuple.
The **kwargs will give you all keyword arguments except for those corresponding to a formal parameter as a dictionary.
See the PEP 3102 about Keyword-Only Arguments.

Python 3.7.5 : The this python package.

The this python package is simple to use:

[mythcat@desk ~]$ python3 
Python 3.7.5 (default, Dec 15 2019, 17:54:26) 
[GCC 9.2.1 20190827 (Red Hat 9.2.1-1)] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import this
The Zen of Python, by Tim Peters

Beautiful is better than ugly.
Explicit is better than implicit.
Simple is better than complex.
Complex is better than complicated.
Flat is better than nested.
Sparse is better than dense.
Readability counts.
Special cases aren't special enough to break the rules.
Although practicality beats purity.
Errors should never pass silently.
Unless explicitly silenced.
In the face of ambiguity, refuse the temptation to guess.
There should be one-- and preferably only one --obvious way to do it.
Although that way may not be obvious at first unless you're Dutch.
Now is better than never.
Although never is often better than *right* now.
If the implementation is hard to explain, it's a bad idea.
If the implementation is easy to explain, it may be a good idea.
Namespaces are one honking great idea -- let's do more of those!