Public Subnets

Overview

The Public Subnets insight focuses on identifying and providing visibility into all public subnets within your Azure Virtual Network (VNet) environment. Public subnets are those that have direct access to the internet, making them critical components of your infrastructure that require careful management and monitoring. This insight is invaluable for IT Operations (IT Ops) and Security Operations (Sec Ops) engineers to ensure that public subnets are configured securely and in compliance with organizational and regulatory requirements.

Value to IT and Security Engineers

For IT Engineers:

• Network Design Validation: Ensures that public subnets are appropriately placed within your architecture to support intended workloads and services.

• Troubleshooting Support: Facilitates faster identification of connectivity issues by isolating public subnet configurations.

• Operational Efficiency: Tracks public subnets to prevent misconfigurations that could lead to service disruptions or inefficiencies.

For Security Engineers:

• Attack Surface Management: Identifies public subnets to ensure that only required resources have internet access, reducing the attack surface.

• Compliance Verification: Validates that public subnets are secured and meet tagging, naming, and configuration compliance standards.

• Threat Mitigation: Helps detect risky configurations, such as overly permissive security group rules, that could expose resources to unauthorized access.

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Key Use Cases

1. Auditing Public Access: Engineers can audit all public subnets to confirm that only necessary resources are exposed to the internet, reducing risks of unauthorized access or data breaches.

2. Ensuring Proper Security Group Association: Public subnets can be reviewed to ensure they are associated with appropriately restrictive security groups to prevent malicious traffic.

3. Compliance Enforcement: Helps teams ensure that all public subnets are configured according to organizational policies, such as encryption and tagging requirements.

4. Resource Segmentation: Provides clarity on which resources are placed in public subnets versus private subnets, enabling better resource segregation and security.

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Actionable Insights

• Identify Overly Permissive Configurations: Regularly review public subnets to ensure they do not have overly permissive inbound or outbound rules, such as wide-open access on all ports.

• Monitor Resource Placement: Confirm that only resources requiring public internet access, such as web servers or public APIs, are hosted in public subnets.

• Enforce Least Privilege Access: Ensure that security group rules associated with public subnets follow the principle of least privilege by restricting access to specific IPs or ranges.

• Validate Internet Gateway Associations: Check that public subnets are correctly associated with an internet gateway to enable secure and monitored traffic flow.

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Additional Recommendations

• Use Network Security Groups (NSGs): Apply NSGs to public subnets to enforce granular control over inbound and outbound traffic.

• Enable Monitoring Tools: Utilize Azure Monitor and Network Watcher to set up alerts for unusual traffic patterns or changes to public subnet configurations.

• Regularly Audit Access Logs: Analyze logs from public-facing resources to detect any unauthorized or suspicious activity.

• Implement DDoS Protection: Enable Azure DDoS Protection for critical resources in public subnets to safeguard against distributed denial-of-service attacks.

By leveraging the Public Subnets insight, IT Ops and Sec Ops engineers can enhance their network security posture, ensure compliance, and maintain efficient operational workflows.