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Database

Insecurely generated cookies - SameSite

Need

To protect cookies from being sent along with cross-site requests

Context

• Usage of Elixir for building scalable and fault-tolerant applications

• Usage of Plug Cowboy for building web applications in Elixir

• Usage of secure cookie handling

Description

1. Non compliant code

defmodule Vulnerable do
  use Plug.Router

  plug :match
  plug :dispatch

  post "" do
    |> put_resp_cookie("sensitive_info", "some_value")...

In this Elixir code snippet, a cookie is being set without the SameSite attribute, making it susceptible to being sent along with cross-site requests.

2. Steps

• Set the SameSite attribute to 'Strict' or 'Lax' while setting the cookies.

• Do not store sensitive information in cookies if possible.

3. Secure code example

defmodule Secure do
  use Plug.Router

  plug :match
  plug :dispatch

  post "" do
    |> put_resp_cookie("sensitive_info", "some_value", same_site: "Strict")...

In this Elixir code snippet, the cookie is set with the SameSite attribute set to 'Strict', protecting it from being sent along with cross-site requests.

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