Azure security baseline for Application Gateway

This security baseline applies guidance from the Microsoft cloud security benchmark version 1.0 to Application Gateway. The Microsoft cloud security benchmark provides recommendations on how you can secure your cloud solutions on Azure. The content is grouped by the security controls defined by the Microsoft cloud security benchmark and the related guidance applicable to Application Gateway.

You can monitor this security baseline and its recommendations using Microsoft Defender for Cloud. Azure Policy definitions will be listed in the Regulatory Compliance section of the Microsoft Defender for Cloud portal page.

When a feature has relevant Azure Policy Definitions, they are listed in this baseline to help you measure compliance with the Microsoft cloud security benchmark controls and recommendations. Some recommendations may require a paid Microsoft Defender plan to enable certain security scenarios.

Note

Features not applicable to Application Gateway have been excluded. To see how Application Gateway completely maps to the Microsoft cloud security benchmark, see the full Application Gateway security baseline mapping file.

Security profile

The security profile summarizes high-impact behaviors of Application Gateway, which may result in increased security considerations.

Service Behavior Attribute	Value
Product Category	Networking
Customer can access HOST / OS	No Access
Service can be deployed into customer's virtual network	True
Stores customer content at rest	True

Network security

For more information, see the Microsoft cloud security benchmark: Network security.

NS-1: Establish network segmentation boundaries

Features

Virtual Network Integration

Description: Service supports deployment into customer's private Virtual Network (VNet). Learn more.

Supported	Enabled By Default	Configuration Responsibility
True	True	Microsoft

Configuration Guidance: No additional configurations are required as this is enabled on a default deployment.

Reference: Application Gateway infrastructure configuration

Network Security Group Support

Description: Service network traffic respects Network Security Groups rule assignment on its subnets. Learn more.

Supported	Enabled By Default	Configuration Responsibility
True	False	Customer

Configuration Guidance: Use network security groups (NSG) to restrict or monitor traffic by port, protocol, source IP address, or destination IP address. Create NSG rules to restrict your service's open ports (such as preventing management ports from being accessed from untrusted networks). Be aware that by default, NSGs deny all inbound traffic but allow traffic from virtual network and Azure Load Balancers.

Reference: Network security groups

Microsoft Defender for Cloud monitoring

Azure Policy built-in definitions - Microsoft.Network:

Name (Azure portal)	Description	Effect(s)	Version (GitHub)
Subnets should be associated with a Network Security Group	Protect your subnet from potential threats by restricting access to it with a Network Security Group (NSG). NSGs contain a list of Access Control List (ACL) rules that allow or deny network traffic to your subnet.	AuditIfNotExists, Disabled	3.0.0

NS-2: Secure cloud services with network controls

Features

Azure Private Link

Description: Service native IP filtering capability for filtering network traffic (not to be confused with NSG or Azure Firewall). Learn more.

Supported	Enabled By Default	Configuration Responsibility
True	False	Customer

Configuration Guidance: Deploy private endpoints for all Azure resources that support the Private Link feature, to establish a private access point for the resources.

Reference: Configure Azure Application Gateway Private Link (preview)

Disable Public Network Access

Description: Service supports disabling public network access either through using service-level IP ACL filtering rule (not NSG or Azure Firewall) or using a 'Disable Public Network Access' toggle switch. Learn more.

Supported	Enabled By Default	Configuration Responsibility
False	Not Applicable	Not Applicable

Feature notes: Limited public connectivity is required for the management of Application Gateway.

For more information, please visit: Application Gateway infrastructure configuration

Configuration Guidance: This feature is not supported to secure this service.

Identity management

For more information, see the Microsoft cloud security benchmark: Identity management.

IM-1: Use centralized identity and authentication system

Features

Azure AD Authentication Required for Data Plane Access

Description: Service supports using Azure AD authentication for data plane access. Learn more.

Supported	Enabled By Default	Configuration Responsibility
False	Not Applicable	Not Applicable

Configuration Guidance: This feature is not supported to secure this service.

IM-3: Manage application identities securely and automatically

Features

Managed Identities

Description: Data plane actions support authentication using managed identities. Learn more.

Supported	Enabled By Default	Configuration Responsibility
False	Not Applicable	Not Applicable

Feature notes: Though managed identities from other services may not authenticate to Application Gateway, a managed identity can be used by Application Gateway to authenticate to Azure Key Vault and is optional to be specified at the deployment time. The service honors Azure RBAC controls.

Configuration Guidance: This feature is not supported to secure this service.

IM-8: Restrict the exposure of credential and secrets

Features

Service Credential and Secrets Support Integration and Storage in Azure Key Vault

Description: Data plane supports native use of Azure Key Vault for credential and secrets store. Learn more.

Supported	Enabled By Default	Configuration Responsibility
True	False	Customer

Feature notes: When the customer uploads a TLS certificate, it is automatically stored within a managed Azure Key vault Service.

Application Gateway v1 does not support Azure Key Vault integration. Credentials and certificates are stored in a different secret store.

Configuration Guidance: Ensure that secrets and credentials are stored in secure locations such as Azure Key Vault, instead of embedding them into code or configuration files.

Reference: Configure an Application Gateway with TLS termination using the Azure portal

Privileged access

For more information, see the Microsoft cloud security benchmark: Privileged access.

PA-8: Determine access process for cloud provider support

Features

Customer Lockbox

Description: Customer Lockbox can be used for Microsoft support access. Learn more.

Supported	Enabled By Default	Configuration Responsibility
False	Not Applicable	Not Applicable

Configuration Guidance: This feature is not supported to secure this service.

Data protection

For more information, see the Microsoft cloud security benchmark: Data protection.

DP-1: Discover, classify, and label sensitive data

Features

Sensitive Data Discovery and Classification

Description: Tools (such as Azure Purview or Azure Information Protection) can be used for data discovery and classification in the service. Learn more.

Supported	Enabled By Default	Configuration Responsibility
False	Not Applicable	Not Applicable

Feature notes: Apart from resource configuration (which includes customer's TLS server certificates), Application Gateway only stores transient data while proxying the requests to customers backend.

Configuration Guidance: This feature is not supported to secure this service.

DP-2: Monitor anomalies and threats targeting sensitive data

Features

Data Leakage/Loss Prevention

Description: Service supports DLP solution to monitor sensitive data movement (in customer's content). Learn more.

Supported	Enabled By Default	Configuration Responsibility
False	Not Applicable	Not Applicable

Configuration Guidance: This feature is not supported to secure this service.

DP-3: Encrypt sensitive data in transit

Features

Data in Transit Encryption

Description: Service supports data in-transit encryption for data plane. Learn more.

Supported	Enabled By Default	Configuration Responsibility
True	False	Customer

Feature notes: Customer's resource configuration data is always transported through TLS channels in the control plane. For the data plane, the service lets customer choose between TCP and TLS variants. Customers choose based on their own needs.

Configuration Guidance: Enable secure transfer in services where there is a native data in transit encryption feature built in. Enforce HTTPS on any web applications and services and ensure TLS v1.2 or later is used. Legacy versions such as SSL 3.0, TLS v1.0 should be disabled. For remote management of Virtual Machines, use SSH (for Linux) or RDP/TLS (for Windows) instead of an unencrypted protocol.

Reference: Overview of TLS termination and end to end TLS with Application Gateway

DP-4: Enable data at rest encryption by default

Features

Data at Rest Encryption Using Platform Keys

Description: Data at-rest encryption using platform keys is supported, any customer content at rest is encrypted with these Microsoft managed keys. Learn more.

Supported	Enabled By Default	Configuration Responsibility
True	True	Microsoft

Feature notes: Customer's data regarding resource configuration is stored in an encryption-enabled storage account and secrets are stored in a managed Azure Key Vault. Only resource configuration data is sent into Kusto for DRI/dev analytics.

Since Application Gateway is proxying product, it doesn't store customer's runtime data traffic and simply proxies it over to the backend. The service does temporarily have the network traffic in an unencrypted form in memory while proxying it to the backend/client.

Configuration Guidance: No additional configurations are required as this is enabled on a default deployment.

DP-6: Use a secure key management process

Features

Key Management in Azure Key Vault

Description: The service supports Azure Key Vault integration for any customer keys, secrets, or certificates. Learn more.

Supported	Enabled By Default	Configuration Responsibility
False	Not Applicable	Not Applicable

Configuration Guidance: This feature is not supported to secure this service.

DP-7: Use a secure certificate management process

Features

Certificate Management in Azure Key Vault

Description: The service supports Azure Key Vault integration for any customer certificates. Learn more.

Supported	Enabled By Default	Configuration Responsibility
True	False	Customer

Feature notes: When the customer uploads a TLS certificate, it is automatically stored within a managed Azure Key vault Service.

Application Gateway v1 does not support Azure Key Vault integration. Credentials and certificates are stored in a different secret store.

Configuration Guidance: Use Azure Key Vault to create and control the certificate lifecycle, including creation, importing, rotation, revocation, storage, and purging of the certificate. Ensure the certificate generation follows defined standards without using any insecure properties, such as: insufficient key size, overly long validity period, insecure cryptography. Setup automatic rotation of the certificate in Azure Key Vault and the Azure service (if supported) based on a defined schedule or when there is a certificate expiration. If automatic rotation is not supported in the application, ensure they are still rotated using manual methods in Azure Key Vault and the application.

Reference: TLS termination with Key Vault certificates

Asset management

For more information, see the Microsoft cloud security benchmark: Asset management.

AM-2: Use only approved services

Features

Azure Policy Support

Description: Service configurations can be monitored and enforced via Azure Policy. Learn more.

Supported	Enabled By Default	Configuration Responsibility
True	False	Customer

Feature notes: Application Gateways are provisioned into the customer's VNet and, barring certain exemptions needed for management traffic, the customer can apply all the needed Azure Policies on a VNet.

Configuration Guidance: Use Microsoft Defender for Cloud to configure Azure Policy to audit and enforce configurations of your Azure resources. Use Azure Monitor to create alerts when there is a configuration deviation detected on the resources. Use Azure Policy [deny] and [deploy if not exists] effects to enforce secure configuration across Azure resources.

Reference: Azure Policy built-in definitions for Azure networking services

Logging and threat detection

For more information, see the Microsoft cloud security benchmark: Logging and threat detection.

LT-1: Enable threat detection capabilities

Features

Microsoft Defender for Service / Product Offering

Description: Service has an offering-specific Microsoft Defender solution to monitor and alert on security issues. Learn more.

Supported	Enabled By Default	Configuration Responsibility
False	Not Applicable	Not Applicable

Configuration Guidance: This feature is not supported to secure this service.

LT-4: Enable logging for security investigation

Features

Azure Resource Logs

Description: Service produces resource logs that can provide enhanced service-specific metrics and logging. The customer can configure these resource logs and send them to their own data sink like a storage account or log analytics workspace. Learn more.

Supported	Enabled By Default	Configuration Responsibility
True	False	Customer

Configuration Guidance: Enable resource logs for the service. For example, Key Vault supports additional resource logs for actions that get a secret from a key vault or and Azure SQL has resource logs that track requests to a database. The content of resource logs varies by the Azure service and resource type.

Reference: Backend health and diagnostic logs for Application Gateway

Next steps

• See the Microsoft cloud security benchmark overview
• Learn more about Azure security baselines