Security Control: Network Security


The most up-to-date Azure Security Benchmark is available here.

Network security recommendations focus on specifying which network protocols, TCP/UDP ports, and network connected services are allowed or denied access to Azure services.

1.1: Protect Azure resources within virtual networks

Azure ID CIS IDs Responsibility
1.1 9.2, 9.4, 14.1, 14.2, 14.3 Customer

Ensure that all Virtual Network subnet deployments have a Network Security Group applied with network access controls specific to your application's trusted ports and sources. When available, use Private Endpoints with Private Link to secure your Azure service resources to your virtual network by extending VNet identity to the service. When Private Endpoints and Private Link not available, use Service Endpoints. For service specific requirements, please refer to the security recommendation for that specific service.

Alternatively, if you have a specific use case, requirement may be met by implementing Azure Firewall.

1.2: Monitor and log the configuration and traffic of virtual networks, subnets, and NICs

Azure ID CIS IDs Responsibility
1.2 9.3, 12.2, 12.8 Customer

Use Azure Security Center and follow network protection recommendations to help secure your network resources in Azure. Enable NSG flow logs and send logs into a Storage Account for traffic audit. You may also send NSG flow logs to a Log Analytics Workspace and use Traffic Analytics to provide insights into traffic flow in your Azure cloud. Some advantages of Traffic Analytics are the ability to visualize network activity and identify hot spots, identify security threats, understand traffic flow patterns, and pinpoint network misconfigurations.

1.3: Protect critical web applications

Azure ID CIS IDs Responsibility
1.3 9.5 Customer

Deploy Azure Web Application Firewall (WAF) in front of critical web applications for additional inspection of incoming traffic. Enable Diagnostic Setting for WAF and ingest logs into a Storage Account, Event Hub, or Log Analytics Workspace.

1.4: Deny communications with known malicious IP addresses

Azure ID CIS IDs Responsibility
1.4 12.3 Customer

Enable DDoS Standard protection on your Azure Virtual Networks to guard against DDoS attacks. Use Azure Security Center Integrated Threat Intelligence to deny communications with known malicious IP addresses.

Deploy Azure Firewall at each of the organization's network boundaries with Threat Intelligence enabled and configured to "Alert and deny" for malicious network traffic.

Use Azure Security Center Just In Time Network access to configure NSGs to limit exposure of endpoints to approved IP addresses for a limited period.

Use Azure Security Center Adaptive Network Hardening to recommend NSG configurations that limit ports and source IPs based on actual traffic and threat intelligence.

1.5: Record network packets

Azure ID CIS IDs Responsibility
1.5 12.5 Customer

Enable Network Watcher packet capture to investigate anomalous activities.

1.6: Deploy network based intrusion detection/intrusion prevention systems (IDS/IPS)

Azure ID CIS IDs Responsibility
1.6 12.6, 12.7 Customer

Select an offer from the Azure Marketplace that supports IDS/IPS functionality with payload inspection capabilities. If intrusion detection and/or prevention based on payload inspection is not a requirement, Azure Firewall with Threat Intelligence can be used. Azure Firewall Threat intelligence-based filtering can alert and deny traffic to and from known malicious IP addresses and domains. The IP addresses and domains are sourced from the Microsoft Threat Intelligence feed.

Deploy the firewall solution of your choice at each of your organization's network boundaries to detect and/or deny malicious traffic.

1.7: Manage traffic to web applications

Azure ID CIS IDs Responsibility
1.7 12.9, 12.10 Customer

Deploy Azure Application Gateway for web applications with HTTPS/TLS enabled for trusted certificates.

1.8: Minimize complexity and administrative overhead of network security rules

Azure ID CIS IDs Responsibility
1.8 1.5 Customer

Use Virtual Network Service Tags to define network access controls on Network Security Groups or Azure Firewall. You can use service tags in place of specific IP addresses when creating security rules. By specifying the service tag name (e.g., ApiManagement) in the appropriate source or destination field of a rule, you can allow or deny the traffic for the corresponding service. Microsoft manages the address prefixes encompassed by the service tag and automatically updates the service tag as addresses change.

You may also use Application Security Groups to help simplify complex security configuration. Application security groups enable you to configure network security as a natural extension of an application's structure, allowing you to group virtual machines and define network security policies based on those groups.

1.9: Maintain standard security configurations for network devices

Azure ID CIS IDs Responsibility
1.9 11.1 Customer

Define and implement standard security configurations for network resources with Azure Policy.

You may also use Azure Blueprints to simplify large scale Azure deployments by packaging key environment artifacts, such as Azure Resources Manager templates, Azure RBAC controls, and policies, in a single blueprint definition. You can apply the blueprint to new subscriptions, and fine-tune control and management through versioning.

1.10: Document traffic configuration rules

Azure ID CIS IDs Responsibility
1.10 11.2 Customer

Use Tags for NSGs and other resources related to network security and traffic flow. For individual NSG rules, use the "Description" field to specify business need and/or duration (etc.) for any rules that allow traffic to/from a network.

Use any of the built-in Azure Policy definitions related to tagging, such as "Require tag and its value" to ensure that all resources are created with Tags and to notify you of existing untagged resources.

You may use Azure PowerShell or Azure CLI to look-up or perform actions on resources based on their Tags.

1.11: Use automated tools to monitor network resource configurations and detect changes

Azure ID CIS IDs Responsibility
1.11 11.3 Customer

Use Azure Activity Log to monitor resource configurations and detect changes to your Azure resources. Create alerts within Azure Monitor that will trigger when changes to critical resources take place.

Next steps