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RonVider / dvpwa

Damn Vulnerable Python Web App
MIT License
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=============================================== DVPWA -- Damn Vulnerable Python Web Application

Description

DVPWA was inspired by famous dvwa project and bobby-tables xkcd comics. The purpose of this project is to implement real-world like application in Python with as many vulnerabilities as possible while having a good design and intentions.

This project was used as demonstration of vulnerabilities during my Web vulnerabilities_ presentation at EVO Summer Python Lab'17.

Running

Docker-compose

DVPWA is packaged into docker container. All the dependencies described in :code:docker-compose.yml. You can easiliy run it and its dependencies using a simple command:

.. code-block :: bash

docker-compose up

Then visit http://localhost:8080 in your favorite browser.

To rebuild the container, please use ./recreate.sh script, which will delete old container and create new from scratch. This script is primarly used in order to rebuild application image.

If you have screwed up the database (i.e. with DROP TABLE students;, please issue the following commands to recreate database container:

.. code-block :: bash

docker-compose stop postgres
docker-compose rm  # make sure, you remove only images you want to recreate
docker-compose up postgres  # recreate container and run

Natively

If for some reasons you cannot use docker or docker-compose you can run the application on your host system.

Requirements


- Python3.6.2
- PostgreSQL database for data storage
- Redis for session storage

Installing and running

.. code-block :: bash

# Install application dependencies.
pip install -r requirements.txt

# Set up postgresql database Further I assume your db user
# is named postgres and database name is sqli

# Create database schema by applying migration 000
psql -U postgres --d sqli --host localhot --port 5432 \
     -f migrations/000-init-schema.sql

# Load fixtures into database
psql -U postgres --d sqli --host localhot --port 5432 \
     -f migrations/001-fixtures.sql

# Modify config/dev.yaml
cat config/dev.yaml <<EOF
db:
  user: postgres
  password: postgres
  host: localhost
  port: 5432
  database: sqli

redis:
  host: localhost
  port: 6379
  db: 0

app:
  host: 0.0.0.0
  port: 8080
EOF

# Run application
python run.py

Then visit http://localhost:8080 in your favorite browser.

Vulnerabilities

Session fixation

Steps to reproduce


1. Open http://localhost:8080.
2. Open browser devtools.
3. Get value for ``AIOHTTP_SESSION`` cookie.
4. Open http://localhost:8080 in the incognito tab.
5. In the incognito tab, change cookie value to the one, obtained in step 3.
6. In the normal tab (the one from steps 1-3) log in as any user.
7. Refresh page in the incognito tab.

Result

You are now logged in the incognito tab as user from step 6 as well.

Mitigation


Rotate session identifiers on every single login and logout. Rotate session
identifiers on every user_id and/or permissions change.

SQL Injection
-------------

Steps to reproduce
  1. Open http://localhost:8080.
  2. Log in as superadmin:superadmin.
  3. Go to http://localhost:8080/students/.
  4. Add new student with the name Robert'); DROP TABLE students CASCADE; --.

Result


Table "students" is deleted from database. You observe error message, which
says: _"relation \"students\" does not exist"_.

Mitigation

Never construct database queries using string concatenation. Use library-provided way to pass parameters and query separated. Use ORM.

Stored XSS

Steps to reproduce


1. Open http://localhost:8080/courses/1/review.
2. Fill in review content with the following payload:

   .. code-block:: html

      <b>Is this bold?</b> Yes!

3. Submit the review by clicking "Save" button.
4. Observe the newly created review. Note that text "Is it bold?" is bold,
   which means review content is probably neither sanitized on input nor
   escaped on output.
5. Open  http://localhost:8080/courses/1/review.
6. Fill in review content with the following payload:

   .. code-block:: html

      <script>
        alert('I am a stored XSS. Your cookies are: ' + document.cookie);
      </script>

7. Submit the review by clicking "Save" button.
8. Observe the result.

Result

Now whenever you load http://localhost:8080/courses/1, you will receive an alert, which displays your cookie. You can play with different ways to inject your custom javascript to the page now: event handlers (i.e. <img src="https://github.com/RonVider/dvpwa/raw/master/nonexistent" onerror="alert(document.cookie)">, links with javascript targets, etc.

Mitigation


Escape all untrusted content, when you output it. In this example, to mitigate
this kind of attack you can set ``autoescape=True`` when setting up templating
engine (Jinja2) in ``sqli/app.py``.
You can also sanitize text, when users input it and prohibit different kinds of
code injection.

Bad choice for storing passwords
--------------------------------

Description

As per check_paswword function <https://github.com/anxolerd/dvpwa/blob/master/sqli/dao/user.py#L40-L41> and database initialization script <https://github.com/anxolerd/dvpwa/blob/master/sqli/dao/user.py#L40-L41>, passwords are not stored in the database themselves, but their md5 hashes.

Here are the problems with such approach:

Mitigation



Password themselves should never be stored in database. Special hash functions
for passwords exist, such as argon2, bcrypt, pbkdf2. These functions should be
used instead of plain text passwords or weak hashes like md5, or fast hash
functions like sha1, sha2. For examples, see `password hashing
<https://pynacl.readthedocs.io/en/stable/password_hashing/>`_ section on PyNaCL
documentation.

Cross-site request forgery
--------------------------

TBA

.. _`dvwa`: http://dvwa.co.uk
.. _`bobby-tables xkcd comics`: https://xkcd.com/327/
.. _`Web vulnerabilities`: https://www.slideshare.net/OlexandrKovalchuk/web-vulnerabilities-78366279