Why ledger verification is non-negotiable
Data integrity isn’t just a buzzword, it’s the backbone of trust in any database system. With the ledger functionality in Azure SQL and SQL Server, organizations have a powerful way to ensure their data hasn’t been tampered with. But here’s the catch: many customers implement ledger tables yet skip the critical step of running the ledger verification procedure. This oversight can leave your data vulnerable and your compliance posture shaky. What is a database digest? Ledger is a feature that allows SQL Server, Azure SQL Database or Azure SQL Managed Instance to cryptographically link transactions in a tamper-evident manner. Think of it as a blockchain-like mechanism inside your database: every transaction is hashed and chained, creating a block. The hash of the latest block in the database ledger is called the database digest. It represents the state of all ledger tables in the database at the time when the block was generated. These digests can be stored externally, such as in immutable storage or Azure Confidential Ledger, to prevent tampering, providing an independent proof of integrity. How does ledger verification work? The ledger verification procedure compares the current state of your ledger tables against the stored digests. It recalculates hashes and validates the chain to confirm that no unauthorized changes have occurred. Without this step, you’re essentially trusting the ledger without verifying it, a dangerous assumption in environments where compliance and security matter. You can launch the verification by running the following stored procedure: DECLARE @digest_locations NVARCHAR(MAX) = (SELECT * FROM sys.database_ledger_digest_locations FOR JSON AUTO, INCLUDE_NULL_VALUES); SELECT @digest_locations as digest_locations; BEGIN TRY EXEC sys.sp_verify_database_ledger_from_digest_storage @digest_locations; SELECT 'Ledger verification succeeded.' AS Result; END TRY BEGIN CATCH THROW; END CATCH Why skipping verification is risky Many organizations assume that enabling ledger tables is enough. It’s not. If you don’t run verification: Tampering goes undetected: A malicious actor could alter historical data without triggering alarms. Compliance gaps: Regulatory frameworks often require proof of integrity, not just theoretical guarantees. False sense of security: Ledger without verification is like encryption without key management, half a solution. Benefits of regular verification Assurance of data integrity: Confirms that your ledger is intact and trustworthy. Audit readiness: Provides verifiable evidence for compliance audits. Early detection: Identifies anomalies before they become catastrophic breaches. Call to action If you’re using ledger tables in SQL Server or Azure SQL, make verification part of your operational routine. Schedule it. Automate it. Treat it as essential, not optional. Your data, your compliance, and your reputation depend on it.
Windows Authentication for Cloud-Native Identities: Modernizing Azure SQL Managed Instance (Preview)
Organizations moving to the cloud often face a critical challenge: maintaining seamless authentication for legacy applications without compromising security or user experience. Today, we’re excited to announce support for Windows Authentication for Microsoft Entra principals on Azure SQL Managed Instance, enabling cloud-native identities to authenticate using familiar Windows credentials. Why This Matters Traditionally, Windows Authentication relied on on-premises Active Directory, making it difficult for businesses adopting a cloud-only strategy to preserve existing authentication models. With this new capability: Hybrid Identity Support: Users synchronized between on-premises AD DS and Microsoft Entra ID can continue using a single set of credentials for both environments. Cloud-Only Identity (Preview): Identities that exist only in Microsoft Entra ID can now leverage Kerberos-based Windows Authentication for workloads like Azure SQL Managed Instance—without requiring domain controllers. This means organizations can modernize infrastructure while maintaining compatibility with legacy apps, reducing friction during migration. Key Benefits Seamless Migration: Move legacy applications to Azure SQL Managed Instance without rewriting authentication logic. Passwordless Security: Combine Windows Authentication with modern credentials like Windows Hello for Business or FIDO2 keys, enabling MFA and reducing password-related risks. Cloud-Native Integration: Microsoft Entra Kerberos acts as a cloud-based Key Distribution Center (KDC), issuing Kerberos tickets for cloud resources such as Azure SQL Managed Instance and Azure Files Breaking Barriers to Cloud Migration Many enterprises hesitate to migrate legacy apps because they depend on Windows Authentication. By extending this capability to cloud-native identities, we remove a major barrier—allowing customers to modernize at their own pace while leveraging familiar authentication models. Learn More https://learn.microsoft.com/en-us/azure/azure-sql/managed-instance/winauth-azuread-overview?view=azuresql Microsoft Entra Kerberos OverviewStep-by-Step Guide: Route Azure SQL Audit Logs to Multiple Log Analytics Workspaces
Scenario: Many organizations need to route audit logs from Azure SQL Database to more than one Log Analytics workspace. For example, your security team may use Microsoft Sentinel in one workspace, while your application team analyzes logs in another. Azure now makes this possible—here’s how to set it up, and what to watch out for. Why Send Audit Logs to Multiple Workspaces? Separation of Duties: Security and application teams can access the logs they need, independently. Integration with Different Tools: Sentinel may use one workspace for SIEM, while app teams use another for analytics. Compliance and Regional Needs: Some organizations must store logs in different regions or workspaces for regulatory reasons. Step-by-Step Guide Enable Auditing to Log Analytics Workspace Go to your Azure SQL Server in the Azure Portal. Under Security, select Auditing. Set the audit destination to your primary Log Analytics workspace, Click Save. Tip: Enabling auditing here automatically creates a diagnostic setting for the selected workspace. Add Diagnostic Settings for Additional Workspaces In azure portal search for Diagnostic settings. Search for your subscription and master database of SQL Server to create diagnostics setting at server level Click + Add diagnostic setting. Name your setting (e.g., “AuditToAppWorkspace”). Under Log, select audit, select SQLSecurityAuditEvents (uncheck “DevOpsAudit” if not needed). Choose an additional Log Analytics workspace as the destination. Click Save. create new setting Note: You can repeat this step to send audit logs to as many workspaces as needed. Example Use Case A customer uses: Workspace A for Microsoft Sentinel (security monitoring) Workspace B for application analytics By configuring multiple diagnostic settings, both teams receive the audit data they need—no manual exports required. Summary Configuring multiple diagnostic settings allows you to send Azure SQL Database audit logs to several Log Analytics workspaces. This is essential for organizations with different teams or compliance needs. Remember: Enable auditing first Add diagnostic settings for each workspace Monitor for cost and avoid duplicate logs References: https://learn.microsoft.com/en-us/azure/azure-sql/database/auditing https://learn.microsoft.com/en-us/azure/azure-monitor/essentials/diagnostic-settingsAzure SQL Database LTR Backup Immutability is now Generally Available
Azure SQL Database is a fully managed, always‑up‑to‑date relational database service built for mission‑critical apps. It delivers built‑in high availability, automated backups, and elastic scale, with strong security and compliance capabilities. Today, I am very excited to announce the General Availability of immutability for Azure SQL DB LTR backups! Azure SQL Database now supports immutable long‑term retention (LTR) backups, stored in write‑once, read‑many (WORM) state for a fixed (customer configured) period. That means your LTR backups cannot be modified or deleted during the lock window—even by highly privileged identities—helping you preserve clean restore points after a cyberattack and strengthen your compliance posture. Why this matters: ransomware targets backups Modern ransomware playbooks don’t stop at encrypting production data—they also attempt to alter or delete backups to block recovery. With backup immutability, Azure SQL Database LTR backups are written to immutable storage and locked for the duration you specify, providing a resilient, tamper‑proof recovery layer so you can restore from a known‑good copy when it matters most. What we’re announcing General Availability of Backup Immutability for Long‑Term Retention (LTR) backups in Azure SQL Database. This GA applies to Azure SQL database LTR backups. What immutability does (and doesn’t) do Prevents changes and deletion of LTR backup artifacts for a defined, locked period (WORM). This protection applies even to highly privileged identities, reducing the risk from compromised admin accounts or insider misuse. Helps address regulatory WORM expectations, supporting customers who must retain non‑erasable, non‑rewritable records (for example, requirements under SEC Rule 17a‑4(f), FINRA Rule 4511(c), and CFTC Rule 1.31(c)–(d)). Always consult your legal/compliance team for your specific obligations. Complements a defense‑in‑depth strategy—it’s not a replacement for identity hygiene, network controls, threat detection, and recovery drills. See Microsoft’s broader ransomware guidance for Azure. How it works (at a glance) When you enable immutability on an LTR policy, Azure SQL Database stores those LTR backups on Azure immutable storage in a WORM state. During the lock window, the backup cannot be modified or deleted; after the lock expires, normal retention/deletion applies per your policy. Key benefits Ransomware‑resilient recovery: Preserve clean restore points that attackers can’t tamper with during the lock period. Compliance‑ready retention: Use WORM‑style retention to help meet industry and regulatory expectations for non‑erasable, non‑rewritable storage. Operational simplicity: Manage immutability alongside your existing Azure SQL Database long‑term retention policies. Get started Choose databases that require immutable LTR backups. Enable immutability on the LTR backup policy and set the retention/lock period aligned to your regulatory and risk requirements. Validate recovery by restoring from an immutable LTR backup. Documentation: Learn more about backup immutability for LTR backups in Azure SQL Database in Microsoft Learn. Tell us what you think We’d love your feedback on scenarios, guidance, and tooling that would make immutable backups even easier to adopt. Share your experiences and suggestions in the Azure SQL community forums and let us know how immutability is helping your organization raise its cyber‑resilience.Announcing Public Preview: Auditing for Fabric SQL Database
We’re excited to announce the public preview of Auditing for Fabric SQL Database—a powerful feature designed to help organizations strengthen security, ensure compliance, and gain deep operational insights into their data environments. Why Auditing Matters Auditing is a cornerstone of data governance. With Fabric SQL Database auditing, you can now easily track and log database activities—answering critical questions like who accessed what data, when, and how. This supports compliance requirements (such as HIPAA and SOX), enables robust threat detection, and provides a foundation for forensic investigations. Key Highlights Flexible Configuration: Choose from default “audit everything,” preconfigured scenarios (like permission changes, login attempts, data reads/writes, schema changes), or define custom action groups and predicate filters for advanced needs. Seamless Access: Audit logs are stored in One Lake, making them easily accessible via T-SQL or One Lake Explorer. Role-Based Access Control: Configuration and log access are governed by both Fabric workspace roles and SQL-level permissions, ensuring only authorized users can view or manage audit data. Retention Settings: Customize how long audit logs are retained to meet your organization’s policy. How It Works Audit logs are written to a secure, read-only folder in One Lake and can be queried using the sys. fn_get_audit_file_v2 T-SQL function. Workspace and artifact IDs are used as identifiers, ensuring logs remain consistent even if databases move across logical servers. Access controls at both the workspace and SQL database level ensure only the right people can configure or view audit logs. Example Use Cases Compliance Monitoring: Validate a full audit trail for regulatory requirements. Security Investigations: Track specific events like permission changes or failed login attempts. Operational Insights: Focus on specific operations (e.g., DML only) or test retention policies. Role-Based Access: Verify audit visibility across different user roles. Getting Started You can configure auditing directly from the Manage SQL Auditing blade in the Fabric Portal. Choose your preferred scenario, set retention, and (optionally) define custom filters—all through a simple, intuitive interface. Learn more about auditing for Fabric SQL database here Data exposed session with demo hereSecuring Azure SQL Database with Microsoft Entra Password-less Authentication: Migration Guide
The Secure Future Initiative is Microsoft’s strategic framework for embedding security into every layer of the data platform—from infrastructure to identity. As part of this initiative, Microsoft Entra authentication for Azure SQL Database offers a modern, password less approach to access control that aligns with Zero Trust principles. By leveraging Entra identities, customers benefit from stronger security postures through multifactor authentication, centralized identity governance, and seamless integration with managed identities and service principals. Onboarding Entra authentication enables organizations to reduce reliance on passwords, simplify access management, and improve auditability across hybrid and cloud environments. With broad support across tools and platforms, and growing customer adoption, Entra authentication is a forward-looking investment in secure, scalable data access. Migration Steps Overview Organizations utilizing SQL authentication can strengthen database security by migrating to Entra Id-based authentication. The following steps outline the process. Identify your logins and users – Review the existing SQL databases, along with all related users and logins, to assess what’s needed for migration. Enable Entra auth on Azure SQL logical servers by assigning a Microsoft Entra admin. Identify all permissions associated with the SQL logins & Database users. Recreate SQL logins and users with Microsoft Entra identities. Upgrade application drivers and libraries to min versions & update application connections to SQL Databases to use Entra based managed identities. Update deployments for SQL logical server resources to have Microsoft Entra-only authentication enabled. For all existing Azure SQL Databases, flip to Entra‑only after validation. Enforce Entra-only for all Azure SQL Databases with Azure Policies (deny). Step 1: Identify your logins and users - Use SQL Auditing Consider using SQL Audit to monitor which identities are accessing your databases. Alternatively, you may use other methods or skip this step if you already have full visibility of all your logins. Configure server‑level SQL Auditing. For more information on turning the server level auditing: Configure Auditing for Azure SQL Database series - part1 | Microsoft Community Hub SQL Audit can be enabled on the logical server, which will enable auditing for all existing and new user databases. When you set up auditing, the audit log will be written to your storage account with the SQL Database audit log format. Use sys.fn_get_audit_file_v2 to query the audit logs in SQL. You can join the audit data with sys.server_principals and sys.database_principals to view users and logins connecting to your databases. The following query is an example of how to do this: SELECT (CASE WHEN database_principal_id > 0 THEN dp.type_desc ELSE NULL END) AS db_user_type , (CASE WHEN server_principal_id > 0 THEN sp.type_desc ELSE NULL END) AS srv_login_type , server_principal_name , server_principal_sid , server_principal_id , database_principal_name , database_principal_id , database_name , SUM(CASE WHEN succeeded = 1 THEN 1 ELSE 0 END) AS sucessful_logins , SUM(CASE WHEN succeeded = 0 THEN 1 ELSE 0 END) AS failed_logins FROM sys.fn_get_audit_file_v2( '<Storage_endpoint>/<Container>/<ServerName>', DEFAULT, DEFAULT, '2023-11-17T08:40:40Z', '2023-11-17T09:10:40Z') -- join on database principals (users) metadata LEFT OUTER JOIN sys.database_principals dp ON database_principal_id = dp.principal_id -- join on server principals (logins) metadata LEFT OUTER JOIN sys.server_principals sp ON server_principal_id = sp.principal_id -- filter to actions DBAF (Database Authentication Failed) and DBAS (Database Authentication Succeeded) WHERE (action_id = 'DBAF' OR action_id = 'DBAS') GROUP BY server_principal_name , server_principal_sid , server_principal_id , database_principal_name , database_principal_id , database_name , dp.type_desc , sp.type_desc Step 2: Enable Microsoft Entra authentication (assign admin) Follow this to enable Entra authentication and assign a Microsoft Entra admin at the server. This is mixed mode; existing SQL auth continues to work. WARNING: Do NOT enable Entra‑only (azureADOnlyAuthentications) yet. That comes in Step 7. Entra admin Recommendation: For production environments, it is advisable to utilize an PIM Enabled Entra group as the server administrator for enhanced access control. Step 3: Identity & document existing permissions (SQL Logins & Users) Retrieve a list of all your SQL auth logins. Make sure to run on the master database.: SELECT * FROM sys.sql_logins List all SQL auth users, run the below query on all user Databases. This would list the users per Database. SELECT * FROM sys.database_principals WHERE TYPE = 'S' Note: You may need only the column ‘name’ to identify the users. List permissions per SQL auth user: SELECT database_principals.name , database_principals.principal_id , database_principals.type_desc , database_permissions.permission_name , CASE WHEN class = 0 THEN 'DATABASE' WHEN class = 3 THEN 'SCHEMA: ' + SCHEMA_NAME(major_id) WHEN class = 4 THEN 'Database Principal: ' + USER_NAME(major_id) ELSE OBJECT_SCHEMA_NAME(database_permissions.major_id) + '.' + OBJECT_NAME(database_permissions.major_id) END AS object_name , columns.name AS column_name , database_permissions.state_desc AS permission_type FROM sys.database_principals AS database_principals INNER JOIN sys.database_permissions AS database_permissions ON database_principals.principal_id = database_permissions.grantee_principal_id LEFT JOIN sys.columns AS columns ON database_permissions.major_id = columns.object_id AND database_permissions.minor_id = columns.column_id WHERE type_desc = 'SQL_USER' ORDER BY database_principals.name Step 4: Create SQL users for your Microsoft Entra identities You can create users(preferred) for all Entra identities. Learn more on Create user The "FROM EXTERNAL PROVIDER" clause in TSQL distinguishes Entra users from SQL authentication users. The most straightforward approach to adding Entra users is to use a managed identity for Azure SQL and grant the required three Graph API permissions. These permissions are necessary for Azure SQL to validate Entra users. User.Read.All: Allows access to Microsoft Entra user information. GroupMember.Read.All: Allows access to Microsoft Entra group information. Application.Read.ALL: Allows access to Microsoft Entra service principal (application) information. For creating Entra users with non-unique display names, use Object_Id in the Create User TSQL: -- Retrieve the Object Id from the Entra blade from the Azure portal. CREATE USER [myapp4466e] FROM EXTERNAL PROVIDER WITH OBJECT_ID = 'aaaaaaaa-0000-1111-2222-bbbbbbbbbbbb' For more information on finding the Entra Object ID: Find tenant ID, domain name, user object ID - Partner Center | Microsoft Learn Alternatively, if granting these API permissions to SQL is undesirable, you may add Entra users directly using the T-SQL commands provided below. In these scenarios, Azure SQL will bypass Entra user validation. Create SQL user for managed identity or an application - This T-SQL code snippet establishes a SQL user for an application or managed identity. Please substitute the `MSIname` and `clientId` (note: use the client id, not the object id), variables with the Display Name and Client ID of your managed identity or application. -- Replace the two variables with the managed identity display name and client ID declare @MSIname sysname = '<Managed Identity/App Display Name>' declare @clientId uniqueidentifier = '<Managed Identity/App Client ID>'; -- convert the guid to the right type and create the SQL user declare @castClientId nvarchar(max) = CONVERT(varchar(max), convert (varbinary(16), @clientId), 1); -- Construct command: CREATE USER [@MSIname] WITH SID = @castClientId, TYPE = E; declare nvarchar(max) = N'CREATE USER [' + @MSIname + '] WITH SID = ' + @castClientId + ', TYPE = E;' EXEC (@cmd) For more information on finding the Entra Client ID: Register a client application in Microsoft Entra ID for the Azure Health Data Services | Microsoft Learn Create SQL user for Microsoft Entra user - Use this T-SQL to create a SQL user for a Microsoft Entra account. Enter your username and object Id: -- Replace the two variables with the MS Entra user alias and object ID declare sysname = '<MS Entra user alias>'; -- (e.g., username@contoso.com) declare uniqueidentifier = '<User Object ID>'; -- convert the guid to the right type declare @castObjectId nvarchar(max) = CONVERT(varchar(max), convert (varbinary(16), ), 1); -- Construct command: CREATE USER [@username] WITH SID = @castObjectId, TYPE = E; declare nvarchar(max) = N'CREATE USER [' + + '] WITH SID = ' + @castObjectId + ', TYPE = E;' EXEC (@cmd) Create SQL user for Microsoft Entra group - This T-SQL snippet creates a SQL user for a Microsoft Entra group. Set groupName and object Id to your values. -- Replace the two variables with the MS Entra group display name and object ID declare @groupName sysname = '<MS Entra group display name>'; -- (e.g., ContosoUsersGroup) declare uniqueidentifier = '<Group Object ID>'; -- convert the guid to the right type and create the SQL user declare @castObjectId nvarchar(max) = CONVERT(varchar(max), convert (varbinary(16), ), 1); -- Construct command: CREATE USER [@groupName] WITH SID = @castObjectId, TYPE = X; declare nvarchar(max) = N'CREATE USER [' + @groupName + '] WITH SID = ' + @castObjectId + ', TYPE = X;' EXEC (@cmd) For more information on finding the Entra Object ID: Find tenant ID, domain name, user object ID - Partner Center | Microsoft Learn Validate SQL user creation - When a user is created correctly, the EntraID column in this query shows the user's original MS Entra ID. select CAST(sid as uniqueidentifier) AS EntraID, * from sys.database_principals Assign permissions to Entra based users – After creating Entra users, assign them SQL permissions to read or write by either using GRANT statements or adding them to roles like db_datareader. Refer to your documentation from Step 3, ensuring you include all necessary user permissions for new Entra SQL users and that security policies remain enforced. Step 5: Update Programmatic Connections Change your application connection strings to managed identities for SQL authentication and test each app for Microsoft Entra compatibility. Upgrade your drivers to these versions or newer. JDBC driver version 7.2.0 (Java) ODBC driver version 17.3 (C/C++, COBOL, Perl, PHP, Python) OLE DB driver version 18.3.0 (COM-based applications) Microsoft.Data.SqlClient 5.2.2+ (ADO.NET) Microsoft.EntityFramework.SqlServer 6.5.0 (Entity Framework) System.Data.SqlClient(SDS) doesn't support managed identity; switch to Microsoft.Data.SqlClient(MDS). If you need to port your applications from SDS to MDS the following cheat sheet will be helpful: https://github.com/dotnet/SqlClient/blob/main/porting-cheat-sheet.md. Microsoft.Data.SqlClient also takes a dependency on these packages & most notably the MSAL for .NET (Version 4.56.0+). Here is an example of Azure web application connecting to Azure SQL, using managed identity. Step 6: Validate No Local Auth Traffic Be sure to switch all your connections to managed identity before you redeploy your Azure SQL logical servers with Microsoft Entra-only authentication turned on. Repeat the use of SQL Audit, just as you did in Step 1, but now to confirm that every connection has moved away from SQL authentication. Once your server is up and running with only Entra authentication, any connections still based on SQL authentication will not work, which could disrupt services. Test your systems thoroughly to verify that everything operates correctly. Step 7: Enable Microsoft Entra‑only & disable local auth Once all your connections & applications are built to use managed identity, you can disable the SQL Authentication, by turning the Entra-only authentication via Azure portal, or using the APIs. Step 8: Enforce at scale (Azure Policy) Additionally, after successful migration and validation, it is recommended to deploy the built-in Azure Policy across your subscriptions to ensure that all SQL resources do not use local authentication. During resource creation, Azure SQL instances will be required to have Microsoft Entra-only authentication enabled. This requirement can be enforced through Azure policies. Best Practices for Entra-Enabled Azure SQL Applications Use exponential backoff with decorrelated jitter for retrying transient SQL errors, and set a max retry cap to avoid resource drain. Separate retry logic for connection setup and query execution. Cache and proactively refresh Entra tokens before expiration. Use Microsoft.Data.SqlClient v3.0+ with Azure.Identity for secure token management. Enable connection pooling and use consistent connection strings. Set appropriate timeouts to prevent hanging operations. Handle token/auth failures with targeted remediation, not blanket retries. Apply least-privilege identity principles; avoid global/shared tokens. Monitor retry counts, failures, and token refreshes via telemetry. Maintain auditing for compliance and security. Enforce TLS 1.2+ (Encrypt=True, TrustServerCertificate=False). Prefer pooled over static connections. Log SQL exception codes for precise error handling. Keep libraries and drivers up to date for latest features and resilience. References Use this resource to troubleshoot issues with Entra authentication (previously known as Azure AD Authentication): Troubleshooting problems related to Azure AD authentication with Azure SQL DB and DW | Microsoft Community Hub To add Entra users from an external tenant, invite them as guest users to the Azure SQL Database's Entra administrator tenant. For more information on adding Entra guest users: Quickstart: Add a guest user and send an invitation - Microsoft Entra External ID | Microsoft Learn Conclusion Migrating to Microsoft Entra password-less authentication for Azure SQL Database is a strategic investment in security, compliance, and operational efficiency. By following this guide and adopting best practices, organizations can reduce risk, improve resilience, and future-proof their data platform in alignment with Microsoft’s Secure Future Initiative.🔐 Public Preview: Backup Immutability for Azure SQL Database LTR Backups
The Ransomware Threat Landscape Ransomware attacks have become one of the most disruptive cybersecurity threats in recent years. These attacks typically follow a destructive pattern: Attackers gain unauthorized access to systems. They encrypt or delete critical data. They demand ransom in exchange for restoring access. Organizations without secure, tamper-proof backups are often left with no choice but to pay the ransom or suffer significant data loss. This is where immutable backups play a critical role in defense. 🛡️ What Is Backup Immutability? Backup immutability ensures that once a backup is created, it cannot be modified or deleted for a specified period. This guarantees: Protection against accidental or malicious deletion. Assurance that backups remain intact and trustworthy. Compliance with regulatory requirements for data retention and integrity. 🚀 Azure SQL Database LTR Backup Immutability (Public Preview) Microsoft has introduced backup immutability for Long-Term Retention (LTR) backups in Azure SQL Database, now available in public preview. This feature allows organizations to apply Write Once, Read Many (WORM) policies to LTR backups stored in Azure Blob Storage. Key Features: Time-based immutability: Locks backups for a defined duration (e.g., 30 days). Legal hold immutability: Retains backups indefinitely until a legal hold is explicitly removed. Tamper-proof storage: Backups cannot be deleted or altered, even by administrators. This ensures that LTR backups remain secure and recoverable, even in the event of a ransomware attack. 📜 Regulatory Requirements for Backup Immutability Many global regulations mandate immutable storage to ensure data integrity and auditability. Here are some key examples: Region Regulation Requirement USA SEC Rule 17a-4(f) Requires broker-dealers to store records in WORM-compliant systems. FINRA Mandates financial records be preserved in a non-rewriteable, non-erasable format. HIPAA Requires healthcare organizations to ensure the integrity and availability of electronic health records. EU GDPR Emphasizes data integrity and the ability to demonstrate compliance through audit trails. Global ISO 27001, PCI-DSS Require secure, tamper-proof data retention for audit and compliance purposes. Azure’s immutable storage capabilities help organizations meet these requirements by ensuring that backup data remains unchanged and verifiable. 🕒 Time-Based vs. Legal Hold Immutability ⏱️ Time-Based Immutability Locks data for a predefined period (e.g., 30 days). Ideal for routine compliance and operational recovery. Automatically expires after the retention period. 📌 Legal Hold Immutability Retains data indefinitely until the hold is explicitly removed. Used in legal investigations, audits, or regulatory inquiries. Overrides time-based policies to ensure data preservation. Both types can be applied to Azure SQL LTR backups, offering flexibility and compliance across different scenarios. 🧩 How Immutability Protects Against Ransomware Immutable backups are a critical component of a layered defense strategy: Tamper-proof: Even if attackers gain access, they cannot delete or encrypt immutable backups. Reliable recovery: Organizations can restore clean data from immutable backups without paying ransom. Compliance-ready: Meets regulatory requirements for data retention and integrity. By enabling immutability for Azure SQL LTR backups, organizations can significantly reduce the risk of data loss and ensure business continuity. ✅ Final Thoughts The public preview of backup immutability for Azure SQL Database LTR backups is a major step forward in ransomware resilience and regulatory compliance. With support for both time-based and legal hold immutability, Azure empowers organizations to: Protect critical data from tampering or deletion. Meet global compliance standards. Recover quickly and confidently from cyberattacks. Immutability is not just a feature—it’s a foundational pillar of modern data protection. Documentation is available at - Backup Immutability for Long-Term Retention Backups - Azure SQL Database | Microsoft LearnConfigure Auditing for Azure SQL Database series - Part2
In the previous blog, we covered how to configure server level audit and database level audit for Azure SQL database with default settings. In this blog we will see how you can manage auditing using PowerShell cmdlets. PowerShell cmdlets to manage auditing for Azure SQL database: Get-AzSqlServerAudit - Get Server Auditing Policy Get-AzSqlDatabaseAudit - Get Database Auditing Policy Set-AzSqlDatabaseAudit - Create or Update Database Auditing Policy Set-AzSqlServerAudit - Create or Update Server Auditing Policy Remove-AzSqlDatabaseAudit - Remove Database Auditing Policy Remove-AzSqlServerAudit - Remove Server Auditing Policy Refer manage Azure SQL database auditing using Azur PowerShell documentation here for more details. Sometimes you might have a requirement to customize auditing for Azure SQL database to meet compliance or achieve parity with your on-premises servers or just audit specific details to meet business needs. Using PowerShell cmdlets, you can configure auditing to audit specific action groups and use predicate expressions to filter queries, logins, schemas, and databases. Before we modify the audit settings let us verify the existing server and database audit configuration Review the existing configuration Set the context to your subscription Set-AzContext -Subscription "xxx-xxxx-xxxx-xxxx" Check server audit configuration Get-AzSqlServerAudit "resource group name " "servername" You can see server audit is enabled with default action groups and target as log analytics workspace 3. Check database audit configuration Get-AzSqlDatabaseAudit "resource group name" "servername" "database name" Database audit is disabled, and you can see no action groups configured and all targets are in disabled state. Here we are discussing customizing audit settings based on a few sample scenarios and you can extend it further based on your requirements. Scenario 1: Exclude a specific login from auditing. Set-AzSqlServerAudit -ResourceGroupName "test" -ServerName "test" -BlobStorageTargetState Enabled -StorageAccountResourceId "xxxxxx" -PredicateExpression "[server_principal_name]!= 'dba'" Scenario 2: Exclude a login and specific database from auditing Set-AzSqlServerAudit -ResourceGroupName "test" -ServerName "test" -BlobStorageTargetState Enabled -StorageAccountResourceId "xxxxxx" -PredicateExpression "[server_principal_name] != ‘dbadmin’ and [database_name] != 'audit'" Scenario 3: Exclude select statements from auditing Set-AzSqlServerAudit -ResourceGroupName "test" -ServerName "sravstestdb" -PredicateExpression "statement not like '[select ]%'" Set-AzSqlServerAudit -ResourceGroupName "test" -ServerName "sravstestdb" -PredicateExpression "statement <> 'exec sp_executesql N’SELECT%’'" Scenario 4: Audit different action groups instead of default ones Set-AzSqlServerAudit -ResourceGroupName "test" -ServerName "test" -LogAnalyticsTargetState Enabled -WorkspaceResourceId "/subscriptions/fa58cf66-caaf-xxxxxxx-xxxxxxxxx/resourceGroups/test/providers/Microsoft.OperationalInsights/workspaces/test" -AuditActionGroup SUCCESSFUL_DATABASE_AUTHENTICATION_GROUP","FAILED_DATABASE_AUTHENTICATION_GROUP","DATABASE_OBJECT_CHANGE_GROUP" Scenario 5: use predicate expression to exclude transaction related actions from batch completed action group Set-AzSqlDatabaseAudit -ResourceGroupName "test" -ServerName "test" -LogAnalyticsTargetState Enabled -WorkspaceResourceId "/subscriptions/fa58cf66-caaf-xxxxxxx-xxxxxxxxx/resourceGroups/test/providers/Microsoft.OperationalInsights/workspaces/test" -AuditActionGroup "Batch_completed_group" -PredicateExpression "additional_information not like '%<transaction_info>%" Scenario 6: use predicate expression to exclude action from a given action group. the below example shows filtering RPC completed events from batch completed action group. to get action id, please refer Filter SQL Server Audit on action_id Set-AzSqlServerAudit -ResourceGroupName "RESOURCE_GROUP" -ServerName "SERVER_NAME" -BlobStorageTargetState Enabled -StorageAccountResourceId "STORAGE_ACCOUNT_RESOURCE_ID" -PredicateExpression "action_id != 541934418" Note: Both Set-AzSqlServerAudit and Set-AzSqlDatabaseAudit overwrites the existing configuration, so when you modify you need to add the default action groups if you still want to audit them. Review the server audit settings, you can see auditing is configured with different action groups and filters. In this blog we have successfully configured server audit with the required audit action groups and filter expressions.Geo-Replication and Transparent Data Encryption Key Management in Azure SQL Database
Transparent data encryption (TDE) in Azure SQL with customer-managed key (CMK) enables Bring Your Own Key (BYOK) scenario for data protection at rest. With customer-managed TDE, the customer is responsible for and in a full control of a key lifecycle management (key creation, upload, rotation, deletion), key usage permissions, and auditing of operations on keys. Geo-replication and Failover Groups in Azure SQL Database creates readable secondary replicas across different regions to support disaster recovery and high availability. There are several considerations when configuring geo-replication for Azure SQL logical servers that use Transparent Data Encryption (TDE) with Customer-Managed Keys (CMK). This blog post provides detailed information about setting up geo-replication for TDE-enabled databases. Understanding the difference between a TDE protector and a server/database Key To understand the geo-replication considerations, I first need to explain the roles of the TDE protector and a server key. The TDE protector is the key responsible for encrypting the Database Encryption Key (DEK), which in turn encrypts the actual database files and transaction logs. It sits at the top of the encryption hierarchy. A server or database key is a broader concept that refers to any key registered at the server or database level in Azure SQL. One of the registered server or database keys is designated as the TDE protector. Multiple keys can be registered, but only one acts as the active protector at any given time. Geo-replication considerations Azure Key Vault considerations In active geo-replication and failover group scenarios, the primary and secondary SQL logical servers can be linked to an Azure Key Vault in any region — they do not need to be located in the same region. Connecting both SQL logical servers to the same key vault reduces the potential for discrepancies in key material that can occur when using separate key vaults. Azure Key Vault incorporates multiple layers of redundancy to ensure the continued availability of keys and key vaults in the event of service or regional failures. The following diagram represents a configuration for paired region (primary and secondary) for an Azure Key Vault cross-failover with Azure SQL setup for geo-replication using a failover group. Azure SQL considerations The primary consideration is to ensure that the server or database keys are present on both the primary and secondary SQL logical servers or databases, and that appropriate permissions have been granted for these keys within Azure Key Vault. The TDE protector used on the primary does not need to be identical to the one used on the secondary. It is sufficient to have the same key material available on both the primary and secondary systems. You can add keys to a SQL logical server with the Azure Portal, PowerShell, Azure CLI or REST API. Assign user-assigned managed identities (UMI) to primary and secondary SQL servers for flexibility across regions and failover scenarios. Grant Get, WrapKey, UnwrapKey permissions to these identities on the key vault. For Azure Key Vaults using Azure RBAC for access configuration, the Key Vault Crypto Service Encryption User role is needed by the server identity to be able to use the key for encryption and decryption operations. Different encryption key combinations Based on interactions with customers and analysis of livesite incidents involving geo-replication with TDE CMK, we noticed that many clients do not configure the primary and secondary servers with the same TDE protector, due to differing compliance requirements. In this chapter, I will explain how you can set up a failover group with 2 different TDE protectors. This scenario will use TDECMK key as the TDE protector on the primary server (tdesql) and TDECMK2 key as the TDE protector on the secondary server (tdedr). As a sidenote, you can also enable the Auto-rotate key to allow end-to-end, zero-touch rotation of the TDE protector Both logical SQL Servers have access to the Azure Key Vault keys. Next step is to create the failover group and replicate 1 database called ContosoHR. The setup of the failover group failed because the CMK key from the primary server was (intentionally) not added to the secondary server. Adding a server key can easily be done with the Add-AzSqlServerKeyVaultKey command. For example: Add-AzSqlServerKeyVaultKey -KeyId 'https://xxxxx.vault.azure.net/keys/TDECMK/ 01234567890123456789012345678901' -ServerName 'tdedr' -ResourceGroupName 'TDEDemo' After the failover group setup, the sample database on the secondary server becomes available and uses the primary's CMK (TDECMK), regardless of the secondary's CMK configuration. You can verify this by running the following query both on primary and secondary server. SELECT DB_NAME(db_id()) AS database_name, dek.encryption_state, dek.encryption_state_desc, -- SQL 2019+ / Azure SQL dek.key_algorithm, dek.key_length, dek.encryptor_type, -- CERTIFICATE (service-managed) or ASYMMETRIC KEY (BYOK/CMK) dek.encryptor_thumbprint FROM sys.dm_database_encryption_keys AS dek WHERE database_id <> 2 ; database_name encryption_state_desc encryptor_type encryptor_thumbprint ContosoHR ENCRYPTED ASYMMETRIC KEY 0xC8F041FB93531FA26BF488740C9AC7D3B5827EF5 The encryptor_type column shows ASYMMETRIC KEY, which means the database uses a CMK for encryption. The encryptor_thumbprint should match on both the primary and secondary servers, indicating that the secondary database is encrypted using the CMK from the primary server. The TDE protector on the secondary server (TDECMK2) becomes active only in the event of a failover, when the primary and secondary server roles are reversed. As illustrated in the image below, the roles of my primary and secondary servers have been reversed. If the above query is executed again following a failover, the encryptor_thumbprint value will be different, which indicates that the database is now encrypted using the TDE protector (TDECMK2) from the secondary server. database_name encryption_state_desc encryptor_type encryptor_thumbprint ContosoHR ENCRYPTED ASYMMETRIC KEY 0x788E5ACA1001C87BA7354122B7D93B8B7894918D As previously mentioned, please ensure that the server or database keys are available on both the primary and secondary SQL logical servers or databases. Additionally, verify that the appropriate permissions for these keys have been granted within Azure Key Vault. This scenario is comparable to other configurations, such as: The primary server uses SMK while the secondary server uses CMK. The primary server uses CMK while the secondary server uses SMK. Conclusion Understanding the distinction between the TDE protector and server keys is essential for geo-replication with Azure SQL. The TDE protector encrypts the database encryption key, while server keys refer to any key registered at the server or database level in Azure SQL. For successful geo-replication setup and failover, all necessary keys must be created and available on both primary and secondary servers. It is possible and, in certain cases, required to configure different TDE protectors on replicas, as long as the key material is available on each server.Everything you need to know about TDE key management for database restore
Transparent data encryption (TDE) in Azure SQL with customer-managed key (CMK) supports Bring Your Own Key (BYOK) for data protection at rest and facilitates separation of duties in key and data management. With customer-managed TDE, the user manages the lifecycle of keys (creation, upload, rotation, deletion), usage permissions, and auditing of key operations. The key used for encrypting the Database Encryption Key (DEK), known as the TDE protector, is an asymmetric key managed by the customer and stored in Azure Key Vault (AKV). Once a database is encrypted with TDE using a Key Vault key, new backups are encrypted with the same TDE protector. Changing the TDE protector does not update old backups to use the new protector. To restore a backup encrypted with a Key Vault TDE protector, ensure that the key material is accessible to the target server. The TDE feature was designed with the requirement that both the current and previous TDE protectors are necessary for successful restores. It is recommended to retain all previous versions of the TDE protector in the key vault to enable the restore of database backups. This blog post will provide detailed information on which keys should be available for a database restore and the reasons why they are necessary. Encryption of the transaction log file To understand which keys are required for a point-in-time restore, it is necessary to first explain how the transaction log encryption operates. The SQL Server Database Engine divides each physical log file into several virtual log files (VLFs). Each VLF has its own header. Encrypting the entire log file in one single sweep is not possible, so each VLF is encrypted individually and the encryptor information is stored in the VLF header. When the log manager needs to read a particular VLF for recovery, it uses the encryptor information in the VLF header to locate the encryptor and decrypt the VLF. Unencrypted transaction log Consider the following sequence of blocks as the logical log file, where each block represents a Virtual Log File (VLF). Initially, we are in VLF1, and the current Log Sequence Number (LSN) is within VLF1. Transparent data encryption enabled When TDE is enabled on the database, the current VLF is filled with non-operational log records, and a new VLF (VLF2) is created. Each VLF has one header containing the encryptor information, so whenever the encryptor information changes, the log rolls over to the next VLF boundary. The subsequent VLF will contain the new DEK (DEK_1) and the thumbprint of the encryptor of the DEK in the header. Any additions to the log file will be added to VLF2 and will be encrypted. When VLF2 reaches capacity, a new VLF (VLF3) will be generated. Since encryption is enabled, the new VLF will contain the DEK and its information in its header, and it will also be encrypted. Key rotation When a new DEK is generated or its encryptor changes, the log rolls over to the next VLF boundary. The new VLF (VLF4) will contain the updated DEK and encryptor information. For example, if a new DEK (DEK_2) is generated via key rotation in the Azure Portal, VLF3 will fill with non-operational commands before VLF4 is created and encrypted by the new DEK. A database can use multiple keys at a single time Currently, for server and database level CMK, after a key rotation, some of the active VLFs may still be encrypted with an old key. As key rotations are allowed before these VLFs are flushed, the database can end up using multiple keys simultaneously. To ensure that at a certain point in time, the database is using only the current encryption protector (primary generation p) and the old encryption protector (generation p-1) we used the following approach: Block a protector change operation when there is any active VLF using an old thumbprint different from the current encryption protector. When a customer attempts a protector change or the key is being auto rotated, we will verify if there are any VLFs using the old thumbprint that are "active". If so, the protector change will be blocked. If there are no "active VLFs" using the old thumbprint, we take a log backup to flush the inactive VLFs, then rotate the protector and wait for it to fully rotate. This approach ensures that the database will use 2 keys at any given time. Example Time t0 = DB is created without encryption Time t1 = DB is protected by Thumbprint A Time t2 = DB protector is rotated to Thumbprint B Time t3 = Customer requests a protector change to Thumbprint C We check the active VLFs, they are using Thumbprint A and we block the change This ensures that currently the DB is only using Thumbprint A and Thumbprint B Time t4 = Customer requests a protector change to Thumbprint C We check the active VLFs, and none of them are using thumbprint A. We solicit a log backup, that should flush the inactive VLFs using thumbprint A Then we rotate the encryption protector and succeed the operation only when both (b) and (c) are fully complete This approach ensures that after time t4, the DB is only using Thumbprint B and Thumbprint C Point-in-time restore Based on the provided information, it is evident that multiple keys are necessary for a restore if key rotations have taken place. To restore a backup encrypted with a TDE protector from Azure Key Vault, ensure that the key material is accessible to the target server. Therefore, we recommend that you keep the old versions of the TDE protector in the Azure Key Vault, so database backups can be restored. To mitigate it, run the Get-AzSqlServerKeyVaultKey cmdlet for the target server or Get-AzSqlInstanceKeyVaultKey for the target managed instance to return the list of available keys and identify the missing ones. To ensure all backups can be restored, make sure the target server for the restore has access to all of keys needed. These keys don't need to be marked as TDE protector. Backed up log files remain encrypted with the original TDE protector, even if it was rotated and the database is now using a new TDE protector. At restore time, both keys are needed to restore the database. If the log file is using a TDE protector stored in Azure Key Vault, this key is needed at restore time, even if the database has been changed to use service-managed TDE in the meantime. Point-in-time restore example When a customer wants to restore data to a specific point in time (tx), they will need the current encryption protector (p) and the old encryption protector (p-1) from the period [tx-8 days] to [tx]. The reason for using tx-8 is that there is a full backup every 7 days, so we expect to have a complete backup within the last 8 days. Because VLFs may remain active with the earlier key, the system is designed to use the two latest thumbprints (p-2 and p-3) from outside the buffer period. Consider the following timeline: The PITR request is made for 8/20/2025 (tx), at which point Thumbprint D (p) is active. To ensure we have a full backup, we subtract 8 days, bringing us to 8/12/2025 (tx-8), when Thumbprint C (p-1) is active. Since VLFs might still be active with the previous key, we also need Thumbprint B (p-2) and Thumbprint A (p-3). The required thumbprints for this point-in-time restore are A, B, C and D. Conclusion To restore a backup encrypted with a Key Vault TDE protector, it is essential to ensure that the key material is accessible to the target server. It is recommended to retain all old versions of the TDE protector in the key vault to facilitate the restore of database backups.
