Azure Virtual Network (vNet) Security Checklist

1. Identity and Access Management

1. Use Microsoft Entra ID for authentication and access control
2. Enforce Role-Based Access Control with least privilege
3. Avoid assigning Owner or Contributor at subscription level for networking tasks
4. Use Privileged Identity Management for network administrators
5. Enforce Multi-Factor Authentication for all privileged roles
6. Review role assignments regularly and remove unused access

2. Network Segmentation and Design

1. Segment vNets by workload, environment, and trust level
2. Use subnets to isolate application tiers (web, app, database)
3. Avoid flat network designs
4. Use hub-and-spoke architecture for centralized control
5. Isolate sensitive workloads in dedicated subnets or vNets
6. Implement micro-segmentation where required

3. Network Security Groups (NSGs)

1. Apply NSGs at subnet and NIC levels where appropriate
2. Deny all inbound traffic by default and allow only required ports
3. Restrict outbound traffic instead of allowing all by default
4. Use application security groups to simplify rule management
5. Remove unused or redundant rules
6. Regularly audit NSG configurations

4. Azure Firewall and Traffic Control

1. Deploy Azure Firewall for centralized traffic inspection
2. Use application rules and network rules to control traffic
3. Enable threat intelligence filtering
4. Log and monitor all firewall traffic
5. Avoid direct internet exposure for internal resources
6. Use forced tunneling where required

5. Private Access and Endpoints

1. Use Private Endpoints for PaaS services
2. Disable public endpoints where possible
3. Use Private Link to secure service access
4. Restrict access to internal networks only
5. Validate DNS resolution for private endpoints

6. Connectivity Security (VPN and ExpressRoute)

1. Use strong encryption for VPN connections
2. Restrict VPN access by IP and authentication policies
3. Monitor VPN connection logs
4. Secure ExpressRoute connections with proper routing controls
5. Avoid exposing internal routes unnecessarily
6. Use BGP securely and validate route advertisements

7. DNS and Name Resolution

1. Use Private DNS zones for internal name resolution
2. Secure DNS forwarding between on-premises and Azure
3. Avoid open DNS resolvers
4. Monitor DNS query traffic
5. Protect against DNS spoofing and hijacking

8. Monitoring and Logging

1. Enable NSG flow logs
2. Enable diagnostic logs for vNet components
3. Send logs to Log Analytics or SIEM
4. Monitor traffic patterns and anomalies
5. Set alerts for suspicious activity
6. Review logs regularly

9. Threat Protection

1. Enable Microsoft Defender for Cloud
2. Monitor for unusual network behavior
3. Detect lateral movement attempts
4. Enable DDoS Protection Standard
5. Investigate anomalies promptly

10. Data Protection and Traffic Security

1. Enforce encryption in transit (TLS)
2. Avoid unencrypted protocols
3. Use secure application gateways where required
4. Protect sensitive data flows
5. Restrict access to critical services

11. Governance and Compliance

1. Use Azure Policy to enforce network standards
2. Standardize naming conventions
3. Document network architecture
4. Implement change management processes
5. Regularly review compliance requirements
6. Enforce tagging and classification

12. Backup and Resilience

1. Design for high availability across regions
2. Use availability zones where applicable
3. Plan for failover scenarios
4. Document recovery procedures
5. Test disaster recovery plans

13. Continuous Security Operations

1. Perform regular network security assessments
2. Audit configurations periodically
3. Continuously monitor network activity
4. Update configurations based on threats
5. Validate security posture regularly
6. Maintain documentation

Always use best practices. Never assume trust. Always verify access. Security is not static and must be continuously monitored, reviewed, and improved.