Most firms have sturdy exterior safety, e.g. blocking all entry to manufacturing belongings utilizing a firewall, and requiring a VPN to get “inside” entry to manufacturing environments. Nonetheless, as soon as you might be related to the VPN, the interior techniques are normally very poorly protected, and there may be little to no authentication and authorization for inner instruments and providers.
Two widespread threats to inner safety are compromised worker laptops and provide chain assaults. In these situations, the attacker operates behind the firewall, usually with unrestricted community entry.
Providers with an online ui might be secured utilizing an utility load balancer, e.g. an AWS ALB with OIDC, however how do you shield entry to command line interface (CLI) based mostly instruments? Requiring a username and password for each CLI invocation makes it painful to make use of and storing the credentials on the system leaves them vast open in case the pc they reside on is compromised.
The Command Line
Most inner instruments have a CLI to handle the providers which are used throughout the firm and plenty of are poorly protected. What’s one of the simplest ways to authorize CLIs? And how will you tie authorization into the corporate’s SSO?
One possibility is to deploy Hashicorp Vault, however that’s numerous setup and upkeep, so except you might have a workforce to function it, Vault won’t be an excellent match.
Another choice is the OAuth2 gadget authorization grant (RFC8628), which is what this weblog put up will present you how you can use.
The OAuth 2.0 gadget authorization grant is designed for Web-connected units that both lack a browser to carry out a user-agent-based authorization or are enter constrained to the extent that requiring the person to enter textual content so as to authenticate throughout the authorization circulation is impractical. It allows OAuth purchasers on such units (like good TVs, media consoles, digital image frames, and printers) to acquire person authorization to entry protected sources through the use of a person agent on a separate gadget.
For those who ever used the AWS CLI with Single SignOn, that is what it does.
OAuth2 Machine Movement
The Machine Authorization Movement comprises two completely different paths; one happens on the gadget requesting authorization (the CLI) and the opposite happens in a browser. The browser circulation path, whereby a tool code is certain to the session within the browser, happens as a parallel path half within the gadget circulation path.
Implementing the OAuth Machine Movement
Now we’ll have a look at what the above sequence diagram seems to be like when it’s carried out.
The interior CLI instrument at Rockset is known as rsctl and is written in go. Step one is to provoke the gadget circulation to get a JWT entry token.
$ rsctl login
Trying to routinely open the SSO authorization web page in your default browser.
If the browser doesn't open otherwise you want to use a unique gadget to authorize this request, open the next URL:
https://rockset.auth0.com/activate?user_code=BBLF-JCWB
Then enter the code:
BBLF-JCWB
Efficiently logged in!
In case you are utilizing the CLI after logging in to a different pc, e.g. ssh:ing to a Linux server, and you utilize macOS, you possibly can configure iTerm to routinely open the hyperlink utilizing a “Run command” set off.
The web page that the hyperlink takes you to seems to be like this:
Upon getting confirmed that the “person code” is right (matches with what the CLI reveals), and also you click on “Affirm”, it’ll take you thru the conventional OAuth2 login process (which in our case requires a username, password and {hardware} token).
As soon as the authentication is accomplished, you can be redirected and introduced with a dialog just like the one beneath, and you may shut the browser window.
The CLI has now acquired a jwt entry token which is legitimate for quite a few hours and is used to authenticate by way of inner providers. The token might be cached on disk and reused between CLI invocations all through its lifetime.
While you concern a brand new rsctl command, it’ll learn the cached Entry Token from disk, and use it to authenticate with the interior APIs.
Underneath the Hood
We’ve carried out and open sourced a go module to carry out the gadget authorization circulation (github.com/rockset/device-authorization). It helps each Auth0 and Okta as OAuth suppliers.
Pattern Code
The next code is out there within the instance listing within the git repository.
Embedded content material: https://gist.github.com/pmenglund/5ed2708cdb88b6a6982258aed59a0899
We now have a JWT token, which can be utilized to authenticate REST calls by setting the Authorization header to Bearer: <jwt entry token>
Embedded content material: https://gist.github.com/pmenglund/b2ac7bb15ce25755a69573f5a063cb14
It’s now as much as the receiving finish to validate the bearer token, which might be achieved utilizing an AWS ALB with OIDC authentication or a supplier particular API from the API server.
Offline Validation
Another choice for entry token validation is “offline validation”. In offline validation, the API server will get the general public key used to signal the JWT token from the supplier (and caches the general public key) and performs the validation within the API server, as an alternative of creating a validation request to the supplier.
Residual Threat
One factor this doesn’t shield towards is an attacker with a foothold on the pc that executes the CLI. They’ll simply wait till the person has accomplished the authentication, and they’ll then be capable of act because the person all through the entry token.
To mitigate this danger, you possibly can require a one time password (OTP), e.g. a Yubikey, each time the person performs a privileged motion.
$ rsctl delete useful resource foobar
please enter yubikey OTP: ccccccvfbbcddjtuehgnfrbtublkuufbgeebklrubkhf
useful resource foobar deleted
Closing Ideas
On this weblog, we’ve proven how we constructed and open-sourced a go module to safe the Command Line Interface (CLI) utilizing an OAuth2 gadget authorization circulation that helps each Auth0 and Okta SSO suppliers. You’ll be able to add this go module to your inner instruments and scale back inner safety threats.
