How do you secure sensitive data on Azure at rest and in transit?

Long Answer

Securing sensitive data on Azure is about building multiple layers of protection: encryption, identity, monitoring, and compliance governance. My approach covers both data at rest and data in transit, mapped directly to regulatory requirements like GDPR (data subject rights, data minimization) and HIPAA (health data confidentiality).

1) Encryption at Rest
By default, Azure enables Storage Service Encryption (SSE) for blobs, files, and tables using AES-256. For relational workloads, I configure Transparent Data Encryption (TDE) on SQL Database and Managed Instances. For VMs, Azure Disk Encryption secures OS and data disks. Critical for compliance is key control: I use Azure Key Vault with customer-managed keys (CMKs) instead of platform-managed keys when clients require proof of ownership. Key Vault allows HSM-backed storage, key rotation, and audit trails. For highly sensitive workloads, double encryption (envelope encryption) adds defense in depth.

2) Encryption in Transit
All endpoints enforce TLS 1.2+ with perfect forward secrecy. Applications are configured to require HTTPS; App Gateway or Front Door can enforce this globally. Private Link and ExpressRoute/VPN are used to secure connections between Azure and on-prem or hybrid environments, avoiding exposure on public networks. For APIs, I add mTLS or OAuth 2.0 (AAD-issued tokens) for secure identity binding.

3) Identity and Access Controls
Azure Active Directory (AAD) provides a centralized identity plane. I apply role-based access control (RBAC) with least privilege, plus attribute-based access control (ABAC) when context matters. Managed Identities prevent credential sprawl by granting services short-lived tokens automatically. Privileged Identity Management (PIM) restricts and time-bounds admin access. These steps align with GDPR’s principle of data minimization and HIPAA’s need for strict access auditing.

4) Monitoring, Logging, and DLP
Compliance requires monitoring. I enable Azure Monitor, Log Analytics, and Sentinel for continuous auditing. Access logs show who accessed what and when. Azure Information Protection (AIP) and Microsoft Purview DLP enforce classification and prevent sensitive data exfiltration. Alerts are configured for anomalous behavior, e.g., bulk downloads or policy violations.

5) Compliance Controls
Azure provides Compliance Manager with templates for GDPR, HIPAA, ISO, SOC. I configure resources using Azure Policy and Blueprints to enforce compliance automatically (e.g., all storage accounts must have encryption enabled, TLS required). Audit reports are stored for regulator requests. For HIPAA, I ensure Business Associate Agreements (BAAs) are in place.

6) Backup and Recovery
Backups are encrypted with the same policies as primaries. Recovery vaults are configured with RBAC and soft delete to prevent malicious data loss. GDPR’s “right to erasure” is respected with lifecycle policies for data retention and secure delete options.

7) Governance and Culture
Finally, I ensure key rotation, penetration testing, and incident response plans are built in. Security is not static—Azure Security Center (Defender for Cloud) provides recommendations, threat detection, and compliance score tracking.

Summary
Securing sensitive data on Azure requires encryption at rest, encryption in transit, controlled key management, least-privilege IAM, and monitoring/auditing. Compliance (GDPR, HIPAA) is achieved by aligning these controls with regulatory requirements, using Azure-native tools like Key Vault, Policy, and Sentinel to enforce standards consistently.

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Table

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Common Mistakes

A frequent mistake is assuming Azure’s default encryption alone is enough for compliance. Regulators often require customer-managed keys and proof of rotation. Another is neglecting encryption in transit on internal APIs—plaintext or weak TLS versions still appear. Over-privileged RBAC roles (e.g., everyone as Contributor) create audit failures. Some teams collect logs but don’t centralize or review them, missing security incidents. Ignoring data residency and retention policies can breach GDPR requirements. Skipping Business Associate Agreements (BAAs) when handling PHI leaves HIPAA compliance incomplete. Finally, forgetting secure deletion—retired disks or stale backups—exposes sensitive data outside intended lifecycles.

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Sample Answers (Junior / Mid / Senior)

Junior:
“I enable Storage Service Encryption and TDE for data at rest, and enforce HTTPS with TLS 1.2 for data in transit. I use Azure Key Vault for key storage and RBAC to restrict access.”

Mid-Level:
“I configure SSE, Disk Encryption, and Key Vault with customer-managed keys. For transit, I use TLS 1.2+, Private Link, and VPN/ExpressRoute. RBAC and Managed Identities enforce least privilege. Logs go to Azure Monitor, and Azure Policy ensures encryption is always on.”

Senior:
“My approach layers defense: encryption at rest (SSE, TDE, Disk Encryption with CMKs in HSM-backed Key Vault), encryption in transit (TLS, mTLS, Private Link). Compliance is enforced via Azure Policy, Blueprints, and Compliance Manager. Identity is hardened with AAD, RBAC, ABAC, and PIM. Monitoring and DLP tools (Sentinel, Purview) detect anomalies. For HIPAA, I execute BAAs and ensure PHI handling via lifecycle policies. For GDPR, I configure data residency and erasure workflows. Together, this ensures confidentiality, compliance, and audit readiness.”

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Evaluation Criteria

Interviewers expect candidates to show:

• Knowledge of encryption at rest (SSE, TDE, Disk Encryption).
  
• Use of Key Vault with CMKs/HSMs for key custody and rotation.
  
• Enforcement of TLS 1.2+, HTTPS, Private Link/ExpressRoute for secure transport.
  
• Strong IAM practices: RBAC least privilege, PIM, Managed Identities.
  
• Monitoring and DLP integration with Azure Monitor, Sentinel, Purview.
  
• Compliance automation using Azure Policy, Blueprints, Compliance Manager.
  
• GDPR awareness: data residency, right-to-erasure, retention policies.
  
• HIPAA awareness: BAAs, PHI safeguards, audit logs.
  

Weak answers rely only on “Azure encrypts by default.” Strong answers link tools to compliance outcomes and describe how monitoring, identity, and lifecycle management are used for end-to-end data protection.

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Preparation Tips

Before interviews, review Azure Security Center/Defender for Cloud and Microsoft Purview documentation. Practice configuring Key Vault CMKs, rotating keys, and enabling TDE. Set up a demo with an encrypted SQL Database and test access with RBAC vs Managed Identity. Run a lab with Private Link and TLS enforcement. Review compliance templates in Azure Policy for GDPR and HIPAA. Study how BAAs are executed for HIPAA workloads. Rehearse a 60–90s explanation showing encryption, IAM, monitoring, and compliance integration. Prepare examples: e.g., enforcing encryption policies with Blueprints, using Sentinel to detect anomalous access, or implementing data retention policies for GDPR.

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Real-world Context

(1058 chars) A healthcare company migrated patient records to Azure SQL. They enabled TDE with CMKs in Key Vault and signed a BAA with Microsoft. Access was restricted via Managed Identities and RBAC. Logs were streamed to Sentinel, which caught anomalous queries from a compromised account. For a European client, Azure Policy enforced all storage accounts to use encryption and restricted data residency to EU regions, ensuring GDPR alignment. A fintech used Private Link and ExpressRoute to keep transaction data off the public internet. They enabled Purview DLP to detect sensitive fields leaving the network. These examples show how Azure-native security and compliance tools (Key Vault, Policy, Sentinel, Purview) integrate to safeguard sensitive data, prove compliance, and reduce audit friction.

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Key Takeaways

• Encrypt data at rest (SSE, TDE, Disk Encryption) with Key Vault CMKs.
  
• Secure transit with TLS 1.2+, HTTPS, Private Link/ExpressRoute.
  
• Enforce RBAC, ABAC, Managed Identities, PIM for access control.
  
• Use Azure Monitor, Sentinel, Purview for logging, anomaly detection, and DLP.
  
• Automate compliance with Azure Policy, Blueprints, Compliance Manager.
  
• Address GDPR (residency, erasure) and HIPAA (BAA, PHI handling) explicitly.
  
  

Practice Exercise

Scenario: You are asked to migrate a hospital records system into Azure. It must meet HIPAA compliance and also host some European patient data under GDPR rules.

Tasks:

1. Enable encryption at rest: turn on TDE for SQL, Disk Encryption for VMs, and use Key Vault CMKs with HSM protection.
   
2. Enforce encryption in transit: configure TLS 1.2+, HTTPS, and Private Link for APIs. Connect on-prem via ExpressRoute.
   
3. Harden identity: apply RBAC least privilege, enforce PIM for admins, and switch apps to Managed Identities.
   
4. Configure logging/monitoring: stream logs to Azure Monitor and Sentinel, with alerts for anomalous access.
   
5. Implement DLP: use Purview/AIP to classify PHI and detect unauthorized movement.
   
6. Automate compliance: apply Azure Policy for encryption enforcement and EU data residency.
   
7. Draft agreements: ensure HIPAA BAA is signed and GDPR erasure processes are documented.
   
8. Test incident response: simulate a breach and confirm logging, alerting, and recovery workflows.
   

Deliverable: Prepare a 60–90s narrative explaining how you layered encryption, IAM, monitoring, and compliance automation to secure sensitive medical and European patient data while meeting HIPAA and GDPR requirements.