Security best practices for Azure Files

This article outlines security best practices for Azure Files. Azure Files offers two distinct storage solutions: cloud-native Azure Files shares, and Azure Files shares hosted on-premises via Azure File Sync.

Azure Files security considerations

Authentication and Authorization

Azure Files supports multiple authentication methods:

Azure Active Directory (Azure AD) Kerberos authentication: Recommended for domain-joined or hybrid identities, providing integrated Kerberos authentication.
Storage account key authentication: Suitable for scenarios where Azure AD authentication is not feasible or for simpler setups. This grants full access to the storage account.
Shared access signatures (SAS): Provides delegated access to resources in your storage account with specific permissions and for a limited time.

Use Role-Based Access Control (RBAC) to grant granular permissions to users and applications accessing Azure Files. Assign roles at the appropriate scope (storage account, container).

Network Security

Protect your Azure Files shares by configuring network access controls:

Service endpoints: Restrict access to your storage account to only come from your virtual network.
Private endpoints: Provide a dedicated IP address for your storage account within your virtual network, enabling private access and preventing exposure to the public internet.
Firewall and virtual networks: Configure storage account firewalls to allow access only from trusted IP addresses or virtual networks.

Tip: For maximum security, use Azure AD Kerberos authentication combined with private endpoints and network firewalls.

Data Encryption

Azure Files encrypts data at rest and in transit:

Encryption in transit: All data transferred to or from Azure Files is encrypted using SMB 3.0 (with encryption enabled) or HTTPS.
Encryption at rest: Data stored in Azure Files is automatically encrypted using AES-256. You can choose to use Microsoft-managed keys or your own customer-managed keys stored in Azure Key Vault.

Azure File Sync Security

If you are using Azure File Sync to synchronize on-premises file servers with Azure Files, consider the following:

Secure the communication between your on-premises servers and Azure using TLS.
Apply the same security best practices for Azure Files to the Azure File Sync service and the Azure Files shares it manages.
Ensure your on-premises servers are hardened and secured.

Common Security Scenarios

Scenario 1: Securely accessing files from an Azure VM

To access Azure Files from an Azure Virtual Machine:

Mount the share using SMB 3.0 with encryption enabled.
Configure network security (service endpoints or private endpoints) for the storage account.
Use Azure AD Kerberos for authentication if the VM is domain-joined. Otherwise, use storage account keys or SAS tokens with least privilege.

Scenario 2: Securely accessing files from an on-premises client

To access Azure Files from an on-premises client:

Ensure your on-premises network can reach the Azure Files endpoint.
Mount the share using SMB 3.0 with encryption.
For on-premises AD domains, consider Azure AD Domain Services or Azure AD Kerberos with hybrid identities.
If using storage account keys, manage them securely and rotate them regularly.

Summary of Best Practices

Area	Best Practice
Authentication	Prefer Azure AD Kerberos. Use SAS for delegated access.
Authorization	Implement RBAC with least privilege.
Network	Use private endpoints and network firewalls. Restrict access.
Data Protection	Leverage encryption in transit and at rest.
Key Management	Rotate storage account keys regularly. Consider customer-managed keys.
Azure File Sync	Secure endpoints, use TLS, and apply Azure Files best practices.

Important: Regularly review your security configurations and access policies to ensure they remain effective and align with your organization's security requirements.