Azure AD Privileged Identity management (Part 1): Zero Trust Model

By Ashwin Venugopal -

 



To read part 2 please click here

Zero Trust Model

Sometime back security was focused on a strong perimeter defense to keep malicious hackers out. Anything outside the was treated as hostile, whereas inside the wall, an organization's systems were trusted, but today's security posture is to assume breach and use the zero trust model. Nowadays security professionals no longer focus on perimeter defense and modern organizations have to support access to data and services evenly from both inside and outside the corporate firewall.

What does Zero Trust mean?

The Zero Trust Model states that you should never assume trust but instead continually validate trust. Instead of assuming everything behind the corporate firewall is safe, the zero trust model assumes breach and verifies each request as though it originates from an open network. It relies on verifiable user and device trust claims to grant access to organizational resources.

The trust determination components are:
  • Identity Provider that establishes a user's identity and related information.
  • Device Directory which validates a device and the device integrity.
  • Policy evaluation service determines whether the user and device confirm to security policies.

  • Access Proxy determines which organizational resources can be accessed. 

Implementing a Zero Trust Security Model

A zero trust model requires signals to inform decisions, policies to make access decisions, and enforcement capabilities to implement those decisions effectively. Here it is explained thoroughly: 

Signal- To make an informed decision.

Decision- Based on organizational policy.

Enforcement- Of the policy across resources

Zero Trust consider many signal sources- from identity systems to device management and security tools- to create context-rich insights that help make informed decisions.

The access request and signal are analyzed to deliver a decision based on finely-tuned access policies, delivering granular, organization-centric access control.

Decisions are then enforced across the entire digital estate- such as read-only access to SaaS app or remediating compromised passwords with a self-service password reset.

 If you can't determine who the user is, you can't establish a trust relationship for other transactions.

Guiding principles of Zero Trust

  1. Verify Explicitly- Always authenticate and authorize based on all available data points, including user identity, location, device health, service or workload, data classification, and anomalies.
  2. Use least privileged access- Limit user access with Just In Time and Just Enough Access (JIT/JEA), risk based adaptive policies, and data protection to protect both data and productivity.
  3. Assume Breach- Minimize blast radius for breaches and prevent lateral movement by segmenting access by network, user, devices, and application awareness. Verify that all sessions are encrypted end to end. Use analytics to get visibility, drive threat detection, and improve defenses.

Microsoft's Zero Trust Architecture

This system works with intune, pushing device configuration requirements to the managed devices. The device then generates the statement of health, which is stored in Azure AD. When the device user requests access to a resource, the device health state is verified as part of the authentication exchange with Azure AD. Below is a simplified reference architecture for our approach to implementing zero trust:


The National Institute of Standards and Technology has a Zero Trust Architecture, NIST 800-207, publication.




To read part 2 please click here










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