Most corporations have robust 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’re linked to the VPN, the inner programs are normally very poorly protected, and there’s little to no authentication and authorization for inner instruments and providers.
Two frequent threats to inner safety are compromised worker laptops and provide chain assaults. In these eventualities, the attacker operates behind the firewall, usually with unrestricted community entry.
Companies with an online ui may be secured utilizing an software load balancer, e.g. an AWS ALB with OIDC, however how do you defend 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 broad open in case the pc they reside on is compromised.
The Command Line
Most inner instruments have a CLI to handle the providers which can be used inside the firm and lots 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 choice is to deploy Hashicorp Vault, however that’s quite a lot of setup and upkeep, so until you’ve a group to function it, Vault won’t be a superb match.
Another choice is the OAuth2 system authorization grant (RFC8628), which is what this weblog submit will present you the right way to use.
The OAuth 2.0 system 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 consumer to enter textual content with a view to authenticate throughout the authorization move is impractical. It allows OAuth purchasers on such units (like sensible TVs, media consoles, digital image frames, and printers) to acquire consumer authorization to entry protected assets through the use of a consumer agent on a separate system.
If you happen to ever used the AWS CLI with Single SignOn, that is what it does.
OAuth2 Machine Move
The Machine Authorization Move accommodates two completely different paths; one happens on the system requesting authorization (the CLI) and the opposite happens in a browser. The browser move path, whereby a tool code is sure to the session within the browser, happens as a parallel path half within the system move path.
Implementing the OAuth Machine Move
Now we’ll have a look at what the above sequence diagram appears to be like like when it’s carried out.
The interior CLI device at Rockset is known as rsctl and is written in go. Step one is to provoke the system move 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 special system 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 employ 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 appears to be like like this:
After getting confirmed that the “consumer code” is appropriate (matches with what the CLI exhibits), and also you click on “Verify”, it can take you thru the traditional OAuth2 login process (which in our case requires a username, password and {hardware} token).
As soon as the authentication is accomplished, you’ll be redirected and introduced with a dialog just like the one under, and you’ll shut the browser window.
The CLI has now obtained a jwt entry token which is legitimate for a lot of hours and is used to authenticate through inner providers. The token may be cached on disk and reused between CLI invocations during its lifetime.
If you concern a brand new rsctl command, it can learn the cached Entry Token from disk, and use it to authenticate with the inner APIs.
Beneath the Hood
We have now carried out and open sourced a go module to carry out the system authorization move (github.com/rockset/device-authorization). It helps each Auth0 and Okta as OAuth suppliers.
Pattern Code
The next code is on the market 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 may be completed 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 defend in opposition to is an attacker with a foothold on the pc that executes the CLI. They will simply wait till the consumer has accomplished the authentication, and they’ll then be capable to act because the consumer during the entry token.
To mitigate this danger, you possibly can require a one time password (OTP), e.g. a Yubikey, each time the consumer performs a privileged motion.
$ rsctl delete useful resource foobar
please enter yubikey OTP: ccccccvfbbcddjtuehgnfrbtublkuufbgeebklrubkhf
useful resource foobar deleted
Closing Ideas
On this weblog, we now have proven how we constructed and open-sourced a go module to safe the Command Line Interface (CLI) utilizing an OAuth2 system authorization move that helps each Auth0 and Okta SSO suppliers. You may add this go module to your inner instruments and scale back inner safety threats.