Implementing Identity Verification for Zero Trust

Prerequisites

• Understanding of zero trust principles (NIST SP 800-207)
• Familiarity with identity providers (Azure AD, Okta, Ping Identity)
• Knowledge of authentication protocols (SAML 2.0, OIDC, FIDO2)
• Understanding of MFA and passwordless authentication

Overview

Identity is the foundational pillar of zero trust architecture. NIST SP 800-207 mandates that all resource authentication and authorization are dynamic and strictly enforced before access is allowed. Identity verification in zero trust goes beyond traditional username/password by implementing continuous, risk-adaptive authentication using multiple signals including device posture, behavioral biometrics, location, and network context.

This skill covers implementing phishing-resistant MFA, continuous identity verification, risk-based conditional access, and identity governance aligned with the CISA Zero Trust Maturity Model Identity Pillar.

When to Use

• When deploying or configuring implementing identity verification for zero trust capabilities in your environment
• When establishing security controls aligned to compliance requirements
• When building or improving security architecture for this domain
• When conducting security assessments that require this implementation

Prerequisites

• Familiarity with zero trust architecture concepts and tools
• Access to a test or lab environment for safe execution
• Python 3.8+ with required dependencies installed
• Appropriate authorization for any testing activities

Architecture

Identity Verification Flow

User Access Request
    │
    v
┌───────────────────────┐
│ Primary Authentication │
│ - FIDO2/WebAuthn key  │
│ - Certificate-based    │
│ - Passwordless         │
└──────────┬────────────┘
           v
┌───────────────────────┐
│ Contextual Assessment  │
│ - Device posture       │
│ - Network location     │
│ - Geo-velocity check   │
│ - Time of access       │
│ - Behavioral baseline  │
└──────────┬────────────┘
           v
┌───────────────────────┐
│ Risk Scoring Engine    │
│ - Aggregate signals    │
│ - Calculate risk score │
│ - Compare to threshold │
└───┬──────────┬────────┘
    │          │
 Low Risk   High Risk
    │          │
    v          v
┌────────┐  ┌──────────────┐
│ Grant  │  │ Step-up Auth  │
│ Access │  │ - Hardware key│
│        │  │ - Biometric   │
│        │  │ - Manager OK  │
└────────┘  └──────────────┘

Identity Provider Architecture

1. Primary IdP: Azure AD / Okta / Ping Identity for centralized identity management
2. FIDO2 Authenticators: Hardware security keys (YubiKey) or platform authenticators (Windows Hello, Touch ID)
3. Risk Engine: Adaptive access using identity threat detection (Microsoft Entra ID Protection, Okta ThreatInsight)
4. Identity Governance: Lifecycle management, access reviews, just-in-time provisioning
5. Privileged Identity: Separate verification for elevated access (CyberArk, BeyondTrust)

Key Concepts

Phishing-Resistant MFA

FIDO2/WebAuthn eliminates phishable credentials by binding authentication to the origin domain. Hardware security keys and platform authenticators provide cryptographic proof of identity without transmitting secrets.

Continuous Identity Verification

Rather than authenticating once at session start, zero trust requires ongoing verification through session token evaluation, behavioral analytics, and periodic re-authentication challenges based on risk signals.

Risk-Based Conditional Access

Conditional access policies evaluate multiple signals (user risk level, sign-in risk, device compliance, location) to dynamically adjust authentication requirements and access grants.

Identity Threat Detection

AI-driven analytics detect compromised identities through impossible travel detection, anomalous sign-in patterns, credential stuffing detection, and token replay attacks.

Workflow

Phase 1: Identity Infrastructure

1. Consolidate Identity Providers

   • Audit all identity sources across the organization
   • Federate to a single authoritative IdP using SAML 2.0 or OIDC
   • Configure SCIM for automated provisioning and deprovisioning
   • Eliminate local accounts and shared credentials

2. Deploy Phishing-Resistant MFA

   • Enroll all users in FIDO2/WebAuthn with hardware security keys
   • Configure platform authenticators (Windows Hello for Business, macOS Touch ID)
   • Disable SMS and voice call as MFA methods (phishable)
   • Create conditional access policy requiring phishing-resistant methods for all sign-ins

3. Configure Conditional Access Policies

   • Require compliant device for access to sensitive applications
   • Block legacy authentication protocols (basic auth, IMAP, POP3)
   • Require MFA for all users from untrusted locations
   • Enforce session time limits with re-authentication
   • Block or require additional verification for high-risk sign-ins

Phase 2: Risk-Based Authentication

4. Enable Identity Threat Detection

   • Activate Microsoft Entra ID Protection or Okta ThreatInsight
   • Configure risk levels: low (allow), medium (require MFA), high (block and investigate)
   • Enable impossible travel detection and anomalous token alerts
   • Integrate identity risk signals with SIEM/SOAR

5. Implement Step-Up Authentication

   • For sensitive operations (privilege elevation, financial transactions), require additional verification
   • Configure step-up policies: re-authenticate with hardware key
   • Integrate with PAM for privileged session approval workflows
   • Log all step-up events for audit trail

Phase 3: Continuous Verification

6. Deploy Continuous Access Evaluation (CAE)

   • Enable Continuous Access Evaluation Protocol (CAEP) for real-time token revocation
   • Configure critical event triggers: user disabled, password changed, location change
   • Test that token revocation occurs within minutes (not hours) of security event
   • Monitor CAE event logs for operational health

7. Implement Session Controls

   • Configure session duration limits based on application sensitivity
   • Enable sign-in frequency controls (re-authenticate every N hours)
   • Implement persistent browser session controls
   • Configure app-enforced restrictions for unmanaged devices

Phase 4: Identity Governance

8. Automate Identity Lifecycle

   • Configure joiner-mover-leaver workflows with HR system integration
   • Automate access provisioning based on role and department
   • Enable just-in-time access for temporary elevated permissions
   • Configure automatic access expiration for contractors and guests

9. Implement Access Reviews

   • Schedule quarterly access certification campaigns
   • Configure automated reminders and escalation
   • Require manager approval for continued access
   • Auto-revoke access for unreviewed certifications

Validation Checklist

• Single authoritative IdP with all applications federated
• FIDO2/WebAuthn enrolled for all users
• SMS and voice MFA methods disabled
• Legacy authentication protocols blocked
• Conditional access policies enforced for all applications
• Identity threat detection active with risk-based policies
• Continuous Access Evaluation enabled and tested
• Step-up authentication configured for sensitive operations
• Identity lifecycle automated with HR integration
• Quarterly access reviews scheduled and operational
• Identity events streaming to SIEM

References

• NIST SP 800-207: Zero Trust Architecture
• NIST SP 800-63B: Digital Identity Guidelines - Authentication
• CISA Zero Trust Maturity Model v2.0 - Identity Pillar
• FIDO Alliance WebAuthn Specification
• Microsoft Entra Conditional Access Documentation