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Hardening Salt

doc/topics/hardening.rst

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.. _hardening-salt:

============== Hardening Salt

This topic contains tips you can use to secure and harden your Salt environment. How you best secure and harden your Salt environment depends heavily on how you use Salt, where you use Salt, how your team is structured, where you get data from, and what kinds of access (internal and external) you require.

.. important:: The guidance here should be taken in combination with :ref:best-practices.

.. important::

Refer to the :ref:`saltstack_security_announcements` documentation in order to stay updated
and secure.

.. warning::

For historical reasons, Salt requires PyCrypto as a "lowest common
denominator". However, `PyCrypto is unmaintained`_ and best practice is to
manually upgrade to use a more maintained library such as `PyCryptodome`_. See
`Issue #52674`_ and `Issue #54115`_ for more info

.. _PyCrypto is unmaintained: https://github.com/dlitz/pycrypto/issues/301#issue-551975699 .. _PyCryptodome: https://pypi.org/project/pycryptodome/ .. _Issue #52674: https://github.com/saltstack/salt/issues/52674 .. _Issue #54115: https://github.com/saltstack/salt/issues/54115

General hardening tips

  • Restrict who can directly log into your Salt master system.
  • Use SSH keys secured with a passphrase to gain access to the Salt master system.
  • Track and secure SSH keys and any other login credentials you and your team need to gain access to the Salt master system.
  • Use a hardened bastion server or a VPN to restrict direct access to the Salt master from the internet.
  • Don't expose the Salt master any more than what is required.
  • Harden the system as you would with any high-priority target.
  • Keep the system patched and up-to-date.
  • Use tight firewall rules. Pay particular attention to TCP/4505 and TCP/4506 on the salt master and avoid exposing these ports unnecessarily.

Salt hardening tips

.. include:: ../_incl/grains_passwords.rst

.. include:: ../_incl/jinja_security.rst

  • Subscribe to salt-users_ or salt-announce_ so you know when new Salt releases are available.
  • Keep your systems up-to-date with the latest patches.
  • Use Salt's Client :ref:ACL system <acl> to avoid having to give out root access in order to run Salt commands.
  • Use Salt's Client :ref:ACL system <acl> to restrict which users can run what commands.
  • Use :ref:external Pillar <all-salt.pillars> to pull data into Salt from external sources so that non-sysadmins (other teams, junior admins, developers, etc) can provide configuration data without needing access to the Salt master.
  • Make heavy use of SLS files that are version-controlled and go through a peer-review/code-review process before they're deployed and run in production. This is good advice even for "one-off" CLI commands because it helps mitigate typos and mistakes.
  • Use salt-api, SSL, and restrict authentication with the :ref:external auth <acl-eauth> system if you need to expose your Salt master to external services.
  • Make use of Salt's event system and :ref:reactor <reactor> to allow minions to signal the Salt master without requiring direct access.
  • Run the salt-master daemon as non-root.
  • Disable which modules are loaded onto minions with the :conf_minion:disable_modules setting. (for example, disable the cmd module if it makes sense in your environment.)
  • Look through the fully-commented sample :ref:master <configuration-examples-master> and :ref:minion <configuration-examples-minion> config files. There are many options for securing an installation.
  • Run :ref:masterless-mode <tutorial-standalone-minion> minions on particularly sensitive minions. There is also :ref:salt-ssh or the :mod:modules.sudo <salt.modules.sudo> if you need to further restrict a minion.
  • Monitor specific security related log messages. Salt salt-master logs attempts to access methods which are not exposed to network clients. These log messages are logged at the error log level and start with Requested method not exposed.

.. _rotating-salt-keys:

Rotating keys

There are several reasons to rotate keys. One example is exposure or a compromised key. An easy way to rotate a key is to remove the existing keys and let the salt-master or salt-minion process generate new keys on restart.

Rotate a minion key

Run the following on the Salt minion:

.. code-block:: shell

salt-call saltutil.regen_keys systemctl stop salt-minion

Run the following on the Salt master:

.. code-block:: shell

salt-key -d <minion-id>

Run the following on the Salt minion:

.. code-block:: shell

systemctl start salt-minion

Run the following on the Salt master:

.. code-block:: shell

salt-key -a <minion-id>

Rotate a master key

Run the following on the Salt master:

.. code-block:: shell

systemctl stop salt-master rm <pki_dir>/master.{pem,pub} systemctl start salt-master

Run the following on the Salt minion:

.. code-block:: shell

systemctl stop salt-minion rm <pki_dir>/minion_master.pub systemctl start salt-minion

.. _salt-users: https://groups.google.com/forum/#!forum/salt-users .. _salt-announce: https://groups.google.com/forum/#!forum/salt-announce

Hardening of syndic setups

Syndics must be run as the same user as their syndic master process. The master of master's will include publisher ACL information in jobs sent to downstream masters via syndics. This means that any minions connected directly to a master of masters will also receive ACL information in jobs being published. For the most secure setup, only connect syndics directly to master of masters.