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Insecurely generated cookies

Need​

Secure generation and handling of cookies

Context​

  • Usage of Python 3 for Python programming and development
  • Usage of Django for building web applications

Description​

Non compliant code​

from django.http import HttpResponse
from django.views.decorators.csrf import csrf_exempt

@csrf_exempt
def set_cookie(request):
    response = HttpResponse("Setting your cookie")
    response.set_cookie('cookie_name', 'cookie_value')
    return response

In the above code, a cookie is being set without any secure attributes. The set_cookie function in Django is used to set a cookie. The first argument is the name of the cookie, and the second argument is the value of the cookie. The issue here is that the set_cookie function has other optional arguments that can be used to secure the cookie, but they are not being used in this instance.

The secure attribute is not set, which means the cookie can be transmitted over insecure channels. This can expose the cookie to man-in-the-middle attacks. The httponly attribute is also not set, which means the cookie can be accessed by JavaScript. This can expose the cookie to cross-site scripting (XSS) attacks.

The samesite attribute is not set either, which means the cookie can be sent with cross-site requests. This can expose the cookie to cross-site request forgery (CSRF) attacks.

In summary, the code is vulnerable because it creates a cookie without any of the security measures that Django provides. This can result in the exposure of sensitive user information.

Steps​

  • Set the 'secure' attribute for the cookie to ensure it is only sent over HTTPS, preventing it from being sent in plain text.
  • Set the 'httponly' attribute to prevent the cookie from being accessed through client-side scripts, reducing the risk of cross-site scripting (XSS) attacks.
  • Consider using the 'samesite' attribute to prevent the cookie from being sent in cross-site requests, reducing the risk of cross-site request forgery (CSRF) attacks.
  • Ensure that the cookie is only accessible to the intended domain by setting the 'domain' attribute appropriately.
  • Set the 'path' attribute to restrict the cookie to a specific path within the domain.
  • Set an appropriate 'max-age' or 'expires' attribute to limit the lifetime of the cookie.

Compliant code​

from django.http import HttpResponse
from django.views.decorators.csrf import csrf_exempt

@csrf_exempt
def set_cookie(request):
    response = HttpResponse("Setting your cookie")
    response.set_cookie('cookie_name', 'cookie_value', secure=True, httponly=True, samesite='Strict', domain='yourdomain.com', path='/yourpath', max_age=3600)
    return response

The updated code now sets several security attributes for the cookie:

  • secure=True: This ensures that the cookie is only sent over HTTPS, preventing it from being sent in plain text. This is important because cookies often contain sensitive information, and sending them in plain text over an unencrypted connection could expose this information to attackers.

  • httponly=True: This prevents the cookie from being accessed through client-side scripts. This is a useful security measure to help prevent cross-site scripting (XSS) attacks, where an attacker might try to access the cookie through JavaScript running in the user's browser.

  • samesite='Strict': This prevents the cookie from being sent in cross-site requests. This is a useful security measure to help prevent cross-site request forgery (CSRF) attacks, where an attacker might try to trick a user into making a request that the attacker controls.

  • domain='yourdomain.com': This ensures that the cookie is only accessible to the intended domain. This is important because if a cookie is accessible to other domains, it could be used in attacks where an attacker controls a different domain.

  • path='/yourpath': This restricts the cookie to a specific path within the domain. This is a useful security measure because it limits the scope of where the cookie can be sent, reducing the potential for it to be used in attacks.

  • max_age=3600: This sets an expiration time for the cookie, limiting its lifetime. This is a useful security measure because it reduces the window of opportunity for an attacker to use the cookie in an attack.

References​

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