April 24, 2024

Armen Tashjian | Safety Engineer, Company Safety

Flow map from User to Okta to External Identity Provider to Device Compliance Check with an arrow back to Okta “User redirected back to Okta to proceed with authentication.”

Pinterest has enforced using managed and compliant gadgets in our Okta authentication circulation, utilizing a passwordless implementation, in order that entry to our instruments all the time requires a wholesome Pinterest gadget.

Following the phishing-based assaults towards our friends within the tech business, Pinterest determined to take a two pronged method to defend towards related assaults. We determined to:

  1. Require a managed and wholesome Pinterest gadget be used to entry all Pinterest sources, even when within the possession of legitimate credentials
  2. Require FIDO2 credentials for consumer authentication

On this submit, we’ll be specializing in how we required using Pinterest managed gadgets in our Okta authentication circulation.

Picture 1: A consumer on an Android gadget is prevented from authenticating. Picture 2: A consumer on macOS is warned about some compliance failures.

There are a number of driving forces behind this initiative:

  • With the introduction of our PinFlex WFH coverage, we anticipated an elevated variety of staff interacting with Pinterest instruments and companies outdoors of the workplace.
  • For worker dealing with instruments, Pinterest is a SaaS-first firm, which implies that the overwhelming majority of our instruments are web accessible. These instruments will stay internet-accessible both by alternative, or due to the shortage of native IP-based allowlisting capabilities.
  • Our urge for food for network-centric safety controls has diminished. Whereas that doesn’t imply that VPN or on-premise network-based entry shall be totally going away, we acknowledge that our default place received’t be to pressure customers to be on a specific community with a purpose to entry sources, particularly a SaaS device.
  • Now we have a set of essential safety controls that solely exist on company-managed gadgets and/or Cellular BYOD with MDM.

We really feel that requiring a managed and wholesome gadget for authentication mitigates a number of the misplaced safety boundaries described above, by making certain that:

  • Phished consumer credentials (whether or not password, OTP, or push notification) won’t lead to entry to Pinterest sources.
  • Web-accessible Pinterest instruments, together with those who could comprise delicate information, can’t be accessed from unmanaged or unknown gadgets.
  • Managed gadgets shall be in a hardened state, making it tougher for adversaries to realize a foothold.

Whereas researching the totally different integration choices inside Okta, a number of issues grew to become obvious for Okta Basic clients:

  1. The present bespoke gadget associated integrations that do exist between MDM suppliers and Okta, reminiscent of Gadget Belief with Jamf or WS1, don’t present complete options to clients.
  2. If an Okta buyer or a possible vendor desires to combine with Okta to do one thing “fascinating” with the authentication circulation, the one avenue for doing so is to determine mutual belief with some external identity provider (IdP), the place these “fascinating” issues can happen.

Due to this fact, we didn’t have a lot of a alternative however to construct and route customers to our personal customized id supplier. Zuul (apologies Netflix) is an OIDC id supplier that the Pinterest safety staff constructed, with a purpose to incorporate our gadget auth and compliance necessities into the Okta authentication circulation.

Flow map from User to Okta to External Identity Provider to Device Compliance Check with an arrow back to Okta “User redirected back to Okta to proceed with authentication.”
Picture 3: Excessive degree circulation diagram of Okta authentication with idP Routing/Discovery

Like a number of the distributors on this house, we combine our IdP with Okta utilizing IdP Routing/Discovery, the place our IdP acts as a trusted exterior id supplier. We combine with Okta utilizing the “IdP as SSO” method, quite than the “IdP as a Issue/MFA” method, because the latter conflicts with our FIDO2 implementation.

At its core, and from Okta’s perspective, our IdP is nothing greater than a compliant OIDC IdP. Nevertheless, now that we’re within the essential path for SSO authentication, all the expertise, in addition to the success of the authentication request, may be enhanced to implement using a managed and compliant gadget.

One of many challenges that must be overcome with any device-based resolution is having the ability to affiliate an authentication try with a selected gadget. This requirement is why a certificate-based method was a pretty possibility.

We challenge certificates to all managed gadgets, together with desktop and cellular platforms, by means of our MDM resolution, which requires customers to authenticate to ensure that a credential to be issued to the gadget. This permits us to:

  1. Decide the consumer id earlier than interacting with them (e.g. FIDO2) by encoding the consumer id within the PKI certificates issued to the gadget throughout MDM enrollment
  2. Affiliate an authentication try with a bodily gadget, because the certificates was issued to that gadget throughout enrollment
  3. Keep away from platform-specific brokers, as certificate-based authentication is natively supported on the platforms that we help at Pinterest, so we’re in a position to reap the benefits of a platform-agnostic method to authentication

Our customized IdP solely helps mTLS authentication with shopper certificates, utilizing certificates which can be tied each to a consumer and gadget. And not using a legitimate shopper certificates, which is just distributed to managed gadgets, authentication to our IdP is just not attainable.

For functions that don’t help Mutual TLS authentication, for the explanations described within the followup weblog submit, a workaround exists to revert again to password-based authentication.

One other hurdle to beat is Okta’s lack of “enforcement” of an exterior id supplier. Though we are able to route customers to an exterior id supplier, Okta doesn’t present the instruments essential to correctly implement using an id supplier.

Okta clearly indicates that using IdP Routing, and corresponding IdP Routing Guidelines, is just not a safety management:

Routing guidelines enhance the end-user sign-in expertise, however they don’t present safety enhancements. You could configure consumer authentication insurance policies in your IdPs independently of your routing guidelines.

This successfully implies that we can’t depend on exterior IdP as being something greater than an “elective” type of authentication. With out taking any further steps to implement using an exterior IdP, it’s trivial to bypass using an exterior IdP by reverting again to Okta username/password-based authentication.

Within the quote above, Okta alludes to “consumer authentication insurance policies” as a way of enforcement. Had these referenced insurance policies been precise “utility sign-on insurance policies,” enforcement would have been a non-issue. Sadly, the one Okta insurance policies that exist are “international sign-on” insurance policies, which can’t account for the inevitable utility exceptions that you’ll seemingly run into, and are due to this fact not sensible to make use of.

SAML Inline Hooks permit for an exterior service to change a SAML assertion earlier than that SAML Assertion is signed by Okta. On the floor, that’s not likely related to a tool authentication resolution, however there may be one notable return sort that piqued our curiosity: the flexibility to reject an entry try by returning an error.

The requests despatched by Okta in a SAML Inline Hook comprise some related details about an utility entry try, together with:

  1. The applying that’s being accessed
  2. The consumer trying to entry the applying
  3. How the consumer’s Okta session was established

Within the examples under, observe the distinction between the “periods” in these two app entry makes an attempt.

Entry try to reject (exterior IdP not used)

Entry try to permit (exterior IdP used)

Because of this we are able to programmatically make an access-based choice for each single utility entry try. For an entry try that ought to proceed, we return an empty response. For entry makes an attempt that have to be rejected, we throw an error. In different phrases, we are able to overcome no matter limitations exist in Okta app sign-on insurance policies by bolting on our personal customized app sign-on coverage utilizing an inline hook.

To enhance the consumer expertise, we additionally revoke a consumer’s Okta session when this error is surfaced.

Within the instance under, a consumer has established an Okta session with one of many many ways in which IdP routing may be bypassed, in an try to bypass our gadget necessities. But, they nonetheless can’t entry an utility that requires our exterior IdP.

User is directed to a 400 bad request screen and has to be redirected back to the hompage.
Picture 4: SAML Inline Hook blocks an utility entry try, as a result of an Okta session that was not established with the right idP

Though SAML Inline Hooks characterize an excellent short-term resolution for us, that is on no account best. SAML Inline Hooks should be enabled on a per utility foundation and might solely be enabled on functions which can be manually configured in Okta, so some reconfiguration of apps is perhaps essential. We’re planning to reconfigure functions that have been downloaded from the Okta Integration Network for the only goal of enabling our SAML Inline Hook on these functions.

We’re hopeful that Okta will launch one thing, in both Okta Basic or OIE, that permits for us to natively implement an IdP on a per utility foundation, with a configuration that additionally permits FIDO2 enforcement. Alternatively, an “Inline Hook” for common authentication that may be universally utilized to each Okta app would even be an fascinating various.

Now that each Okta authentication try requires customers to authenticate towards our IdP, we now have the chance to judge the well being of a tool. The intent of our compliance insurance policies is to implement our safety hardening pointers to make sure that the fleet of gadgets which can be able to accessing our instruments are in compliance and in a hardened state.

Within the occasion {that a} gadget with compliance failures makes an attempt to authenticate, we are able to take a number of actions, together with presenting a warning to the consumer, or for some insurance policies, blocking the authentication try altogether.

User is directed to a screen that reads “There are one or more issues with your device. Warnings: chrome_running_versions and uptime.”
Picture 5: A consumer on macOS is warned about some compliance failures.

Our compliance framework permits for some capabilities that have been essential to us and should not generally seen in different options. This consists of:

  1. Insurance policies which can be outlined as code, permitting us to create advanced insurance policies if essential
  2. Insurance policies that may take into consideration information from as many information sources as wanted. We presently combine with Splunk, Chef, Workspace One, and osquery, with extra integrations deliberate.
  3. “Actions” which can be executed upon the failure of a coverage, two of which we present on this weblog submit (Block/Warn)
  4. The power to slowly shard a brand new coverage throughout the fleet, utilizing our current manufacturing framework for deploying experiments

Under we’ve created an instance coverage to make sure that a consumer authenticating to Okta is doing so from a tool that’s owned by them and logged in on that gadget with an identical username.

Picture 6: A consumer on macOS is prevented from authenticating as their gadget is failing the instance coverage “username_mismatch”.

Under is the code related to this instance coverage. As a way to carry out this analysis, we take information collected from two totally different information sources (Airwatch MDM and osquery), and evaluate the usernames with the individual trying to authenticate to Okta.

Potential future compliance insurance policies may take into consideration:

  1. Patch standing
  2. Malware detection
  3. Safety agent well being
  4. Log ingestion well being
  5. Utility/browser extensions
  6. Kernel/system extensions
  7. Root CAs
  8. CIS hardening pointers
  9. And plenty of different issues!

We’ve solely begun our gadget compliance journey, and an excellent quantity of labor lies forward, together with:

  • Constantly codifying gadget compliance insurance policies
  • Extra integrations, for each amassing information, in addition to performing actions within the occasion of failures
  • Evaluating gadget compliance not simply at authentication time, however on a steady foundation
  • Closing the Okta enforcement gaps by enabling SAML Inline Hooks throughout all apps

A giant thanks to our companions in IT and Site visitors Engineering, for serving to Company Safety to implement this, and a particular point out goes to Jason Craig, a human being.

Keep tuned for some followup weblog posts, together with:

  • Our FIDO2 implementation
  • A extra in depth look into gadget compliance

For any ideas or suggestions, be happy to achieve out to zuul[at]pinterest.com

Thinking about studying extra about this subject? Try the second a part of this weblog article right here: Worker-facing Mutual TLS.

To study extra about engineering at Pinterest, take a look at the remainder of our Engineering Weblog and go to our Pinterest Labs web site. To discover life at Pinterest, go to our Careers web page.