Conditional Access Policies for Defense Contractor Tenants
Conditional Access is the cornerstone of identity-centric security for defense contractors operating in Microsoft Azure Government and GCC-High environments. When properly configured, it enforces the access control requirements that underpin multiple CMMC Level 2 practices. This guide walks through the essential Conditional Access policy configurations for defense contractor tenants.
Why Conditional Access Is Central to CMMC Access Control
CMMC Level 2’s Access Control (AC) domain includes requirements for multi-factor authentication, privileged account management, and least privilege enforcement. Conditional Access in Microsoft Entra ID (formerly Azure AD) is the primary technical mechanism for implementing these controls in cloud-connected environments.
For GCC-High tenants, Conditional Access operates within the same FedRAMP High-authorized boundary as the rest of the tenant. The configuration process is nearly identical to commercial Azure, but you’ll want to verify that any named locations, trusted IPs, or compliance partner integrations are available in the GCC-High environment before designing policies that depend on them.
Baseline Policies Every Defense Contractor Should Implement
Start with these four baseline Conditional Access policies before building anything more complex: First, require MFA for all users—no exceptions for device or location. Second, require MFA for all admin accounts, with phishing-resistant MFA (FIDO2 or certificate-based) strongly recommended for privileged roles. Third, block legacy authentication protocols (SMTP, IMAP, POP3), which don’t support modern MFA. Fourth, require compliant devices for access to CUI-containing applications.
These four policies alone close a significant portion of the access control gaps that C3PAO assessors find in defense contractor environments.
Advanced Policy Configurations for CUI Protection
Beyond baseline MFA, implement these advanced Conditional Access configurations for CUI environments: Sign-in risk policies that require step-up authentication or block access when Microsoft’s risk engine detects anomalous sign-in behavior. Location-based policies that restrict access to CUI applications from specific named locations or block access from high-risk geographies. Session policies that limit download capabilities for unmanaged devices accessing CUI through browser sessions. Token binding configurations that reduce session hijacking risks for high-privilege accounts.
Privileged Identity Management Integration
For CMMC’s privileged access requirements, Conditional Access works best when paired with Microsoft Entra ID Privileged Identity Management (PIM). PIM provides just-in-time privileged access—administrators request elevated access when needed, receive it for a time-limited window, and the access expires automatically. This dramatically reduces your privileged access exposure window.
Configure Conditional Access policies specifically for PIM activation requests, requiring MFA, compliant device, and approved location before elevated access is granted. Document this workflow in your SSP as evidence of privileged access management.
Testing and Monitoring Conditional Access Policies
Conditional Access misconfiguration can lock out users or leave gaps in protection. Always test new policies using the ‘What If’ tool in the Entra admin center before enabling in enforcement mode. Deploy major policy changes in report-only mode for 1–2 weeks to identify unintended consequences.
Monitor Conditional Access sign-in logs in Microsoft Sentinel for policy-related failures that may indicate attack patterns (repeated MFA fatigue attacks, impossible travel events, blocked legacy authentication attempts). Connect Entra ID logs to Sentinel as part of your CMMC-aligned monitoring configuration.
Conclusion
Conditional Access is one of the highest-leverage CMMC controls available to defense contractors in the Microsoft ecosystem. Properly configured, it addresses access control, privileged account management, and multi-factor authentication requirements simultaneously—and generates continuous evidence for C3PAO assessments.
🟢 Need expert Conditional Access configuration for your GCC-High tenant? VSO deploys and manages identity controls for defense contractors as part of our managed services. Get in touch. — CMMC Managed Services | Contact VSO
Frequently Asked Questions
Can we exempt service accounts from MFA Conditional Access policies?
Service accounts present a genuine challenge for MFA requirements. Use managed identities and service principals instead of user accounts where possible. For legacy service accounts, implement IP-based restrictions and use certificate authentication rather than interactive MFA.
What’s the CMMC practice reference for MFA requirements?
IA.3.083 requires multi-factor authentication for local and network access to privileged accounts and for network access to non-privileged accounts. Your Conditional Access MFA policy directly addresses this practice.
How do we handle MFA for employees without smartphones (for TOTP or push authentication)?
FIDO2 hardware keys (like YubiKey) are an excellent alternative to mobile-based MFA. Certificate-based authentication is another option for environments with PKI infrastructure. Both are approved for CMMC and are often preferred for higher-assurance environments.
Does Conditional Access work for on-premises applications accessed via Azure AD App Proxy?
Yes. Azure AD Application Proxy allows on-premises applications to participate in Conditional Access policies. This is a useful approach for defense contractors with hybrid environments who want to extend cloud-based access control to legacy on-premises systems.
How often should we review and update Conditional Access policies?
Review Conditional Access policies at minimum quarterly, and any time you onboard new applications, change your device management configuration, add new privileged roles, or when Microsoft releases new Conditional Access features relevant to your security posture.
