Design principles

I have tried to take security considerations as a first class design principle. While there may be some compromises security-wise, I have tried to do the Right Thing© to minimize risks.

General

• All software components run as a non-privileged (non-root) user. Any user may be used--the pi user is not assumed.
  • indiserver
  • indi-allsky
  • flask
• The user used will be added as a member of the following groups for device access:
  • video - Access to web cameras
  • dialout - Access to serial ports
  • gpio - Access to GPIO pins
  • i2c - Access to I2C bus (sensors)
  • spi - Access to SPI bus (sensors)

Privileged Access

The indi-allsky OS user is assigned the following designated privileged actions:

• Shutdown/reboot system (via web inteface)
• Set system time (via web interface)
• Auto-mount USB sticks

All of these activities are performed via standard SystemD and udisks interfaces. Privileges are assigned using standard polkit definitions.

Passwords

• There is an option to encrypt passwords in the database using Fernet symmetric encryption. The encryption key is stored in /etc/indi-allsky/flask.json as PASSWORD_KEY

Web Interface

The web interface is designed to run with a self-signed server certificate. The certificate is generated on first run of setup.sh and is stored in with the system server certificates in /usr/local/share/ca-certificates/ and added to the system trust store.

• 4096 bit key
• SHA512 hash
• SAN extension

Flask is used as the application server layer. CSRF tokens are used for all server interactions and should prevent most cross-site scripting attacks.

• CSRF tokens to prevent XSS attacks
• HSTS to enforce HTTPS mode
• Argon2 password hashing
• Session cookies are set with secure flag
• SQLAlchemy ORM to prevent SQL injection attacks
• 3 levels of access control
  • Anonymous - only able to view images and videos
  • Staff - Able to view indi-allsky and system configuration, not able to make changes
  • Admin - Full administrative control
• Authentication is provided by flask-login and is controlled via IDs in the indi-allsky database.

File transfers

indi-allsky supports several secure (and unsecure) file transfer protocols. indi-allsky may bypass certificate and host key validations for convenience.

SyncAPI

An internal REST-like interface is implemented to support synchronizing data between indi-allsky instances. An API key is used to create an HMAC signature of the data and [the API key] is never directly transmitted over the network.

Warnings

• indi-allsky uses various astronomy and image manipulation related python libraries. Most of these libraries are community managed and may contain security vulnerabilities.