Securing xDB data with Azure Key Vault and SQL Always Encrypted (part 3)

In part 1 we looked at the reasons for using Always Encrypted for xDB data and creating encryption keys in Azure Key Vault. In part 2 we looked at Column Master Keys and Column Encryption Keys in SQL Server. In this post I will cover the process of encrypting the data.

Before getting onto that topic I should point out that if you encrypt the data now, then your xDB collection, index worker, and search services will no longer be able to read xDB data until you create a Client ID and Client Secret that enable those services to retrieve the key from Azure Key Vault and use it to decrypt the column data in SQL. The documentation on how to do this is currently incorrect, and I will cover this in part 4. There are also some issues with the current documentation for encryption that are covered below.

Overview

The process of encryption entails a number of steps:

  1. Generate a script to recreate the stored procedures in your shard databases
  2. Delete stored procedures from the shards
  3. Disable change tracking on some of the tables in the shards
  4. Configure Always Encrypted on various columns in the shard database tables
  5. Restore the stored procedures
  6. Re-enable change tracking
  7. Grant permissions to the collection user

Encryption checklist

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You will need to do every step listed above on each of your shard database. In order to help keep track of the steps and ensure that you don’t miss anything out, I’ve created a spreadsheet that you can download and mark off each step in the process.

Step 1 – Generate a script containing all stored procedures for each shard

The stored procedures need to be backed up as a script, deleted, and then re-created after encryption. It was not obvious to me how to do this for all Stored Procs in one go, but it turns out there’s a handy trick. Navigate to the shard database Programmability > Stored Procedures area of the tree and click on Stored Procedures:

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Hit function key F7 and the Object Explorer window will come up with all the stored procs listed. Select all of them (except for System Stored Procedures) and then right mouse click, select Script Stored Procedure as > CREATE to > New Query Editor Window (or to file, whatever you prefer):

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A script of all stored procedures will be generated that you can save for use in Step 5.

Step 2 – Delete stored procedures

Using the Object Explorer window as in Step 1, just select all the stored procedures (except for System Stored Procedures) and delete them.

Step 3 – Disable change tracking

Some of the tables need to have change tracking disabled (and re-enabled later on). For each table, right mouse click the table and open the Properties dialog, click Change Tracking from the left menu and turn it off. Alternatively you can use a script that I wrote.

Do this for the following tables:

  • Contacts
  • ContactFacets
  • Interactions
  • InteractionFacets

Step 4 – Configure Always Encrypted

For each of the tables listed below, configure the appropriate encryption type on the appropriate columns. Before doing this, if you are using Azure SQL I recommend that you bump up the DTU’s significantly before encrypting, as it will run a lot faster due to the processor-intensive nature of the encryption. Also, ensure that you have turned off any services that are connected to the databases (xConnect collection service, etc).

NOTE: The documentation is incorrect. Differences are highlighted below.

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To do this, right mouse click each table and select Encryption from the context menu:

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From the modal dialog box, set the encryption type for the columns:

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Click OK and then, er, wait for a while……

Step 5 – Restore the stored procedures

This bit is pretty simple if you followed the list of tables above and encrypted the Identifier and Source columns in the UnlockContactIdentifiersIndex_Staging table. Just run the script for each shard (you did create a script for each shard right?) Otherwise, your stored procedure script will throw an error due to dependencies between tables. If you get the following error, then you’ve missed this table from your encryption:

Msg 402, Level 16, State 2, Procedure UnlockContactIdentifiersIndex, Line 26 [Batch Start Line xxxx]

The data types varbinary and varbinary(700) encrypted with [……] are incompatible in the equal to operator.

If there are any TMP tables left over after encryption then you can safely delete them (e.g. tmp_ms_xx_ContactFacets1 was one that I had left over after encryption).

Step 6 – Enable Change Tracking

You can use the script provided in step 3 above, for this, or do it manually.

Step 7 – Grant permissions to the collection user.

This step will depend on the name of the user that has access to the Collection Shard Map Manager database, since that is the user that accesses the Shards. Look in your connection strings config file for the xConnect Collection service and find the connection string named “collection” and identify the user in the connection string. In my case it was “xcsmmuser” (xConnect Shard Map Manager user). Yours may have a different user name. (Note that this user is not a Contained Database User, unlike most of the other Sitecore database users in the connection strings, because it needs to access more than one database.)

On both shards, run the following commands:

grant VIEW ANY COLUMN MASTER KEY DEFINITION to [your-xcsmmuser];

grant VIEW ANY COLUMN ENCRYPTION KEY DEFINITION to [your-xcsmmuser];

If you later on see the following error in your xConnect logs, then you’ve neglected to do the above step:

[Error] Sitecore.XConnect.Web.Infrastructure.Operations.GetEntitiesOperation`1[Sitecore.XConnect.Contact]: Sitecore.XConnect.Operations.DependencyFailedException: One or more dependencies failed —> Sitecore.Xdb.Collection.Failures.DataProviderException: Cannot access destination table ‘[xdb_collection].[GetContactIdsByIdentifiers_Staging]’. —> System.InvalidOperationException: Cannot access destination table ‘[xdb_collection].[GetContactIdsByIdentifiers_Staging]’. —> System.Data.SqlClient.SqlException: VIEW ANY COLUMN MASTER KEY DEFINITION permission denied in database ‘[shard database]’.

At which point, you are done with encryption but don’t forget to scale down your Azure SQL databases to their prior DTU settings to avoid incurring excess service charges. If you want to start querying encrypted data in SQL Management Studio then you will need to configure your database connection according to this super helpful post otherwise you will not be able to query or view the data. This post is also useful.

In the next article I will look at configuring client Id and Client Secret and configuring the xConnect services.

Securing xDB data with Azure Key Vault and SQL Always Encrypted (part 2)

In Part 1 we looked at the reasons for encrypting xDB data and at creating a key in an Azure Key Vault. In this second article in the series we will look at creating Column Master Keys and Column Encryption Keys in SQL Server. The process needs to be performed on all xDB collection database shards and for each shard you need to create a Column Master Key (CMK) based on the key we created in Part 1 and a Column Encryption Key (CEK) based on the CMK.

Step 1 – create the Column Master Key

Open up SQL Server Management Studio (SSMS) and navigate to the xDB Collection databases. You will most likely have a Shard Map Manager (SMM) and at least 2 Shard databases. The changes you make in the rest of this process will be made to ALL shard databases but the ShardMapManager will not be affected.

Here’s a sample screenshot of the 3 relevant databases (the prefix ma-demo_ is irrelevant, the databases are for illustrative purposes only):

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Expand Xdb.Collection.Shard0 and navigate to Security > Always Encrypted Keys > Column Master Keys.

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From the context menu of the Column Master Keys node, select the New Column Master Key option:

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A modal dialog window will pop up from which you can choose the location of the key (or certificate) from which you will create your Column Master Key (CMK). You can see below the options are available to use a Windows Certificate Store (Current User or Local Machine), Azure Key Vault, or CNG. I have selected Azure Key Vault.

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You will then need to log into your Azure subscription:

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Once logged in, you should see your Key Vault and the key that you created earlier:

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Select the key – in this case “SQL-DEV-AlwaysEncryptedKey” and type a suitable name (in the screenshot above I have called it “DEV-CMK-Shard0”. Click Generate Key. You should now see the new Always Encrypted Column Master Key in your Shard0 database.

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Step 3 – create a Column Encryption Key

Once you have a Column Master Key based on your key (or certificate) in the Azure Key Vault you can create a Column Encryption Key (CEK). The CEK is, as you might expect, the key that is used to encrypt (and decrypt!) the columns in the tables of your database. Each Shard database will have its own CMK and each CEK will be based on the CMK in the appropriate Shard database.

This bit is very simple. Click on the context menu for Column Encryption Keys and select New Column Encryption Key:

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Give the new CEK a name, choose the CMK from the Column master key drop down and click OK.

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If you experience an error like this:

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then go back to Part 1 of this series of articles and revisit Step 2. You need to assign appropriate permissions to your account in order to create the CEK.

Otherwise you should see the following in your Shard0 database:

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You should now have a new CEK in Shard0. Repeat the above steps for the other xDB collection shard database(s) and you will be (nearly) ready to encrypt the data. We will cover off the next step in Part 3 of this series.

Securing xDB data with Azure Key Vault and SQL Always Encrypted (part 1)

Sitecore offers a number of features relating to the protection of Personally Identifiable Information (PII) data and GDPR compliance. The indexing of personal information data is disabled by default and details of how Sitecore addresses GDPR “data subject rights” can be found here. But what about the xDB SQL data ? Experience Profile data and custom facet data is stored in the xDB collection database shards and anyone with privileges to perform SQL queries against that data can easily read this information or, even more worrisome, dump the entire database out to a BACPAC and share that BACPAC file or accidentally leave it on a hard drive somewhere. The Red Cross database leak should be enough to keep you awake at night if you have sensitive personal information in your xDB database (or any other databases for that matter.)

Azure SQL databases created after May 2017 are encrypted “at rest” by default, however that isn’t the whole story. The issue of SQL query access to data or exporting databases from Azure SQL Server via BACPAC is not resolved by encryption at rest. A developer with access to connection strings would be able to query the data and anyone with SQL admin access could export the data and inadvertently or intentionally expose it (hmm, now where did I put that USB stick with 2 Gb of xDB data again?) What can we do to improve the security of the data ? Enter SQL Always Encrypted.

The Security Guide documentation for Sitecore contains a section on configuring SQL Always Encrypted which goes part way to explaining how to achieve this, however it outlines a number of steps that are not explicitly detailed and are a bit impenetrable if you’ve not done them before, as well as requiring you to hunt down the relevant documentation across various sites. There’s also a few gaps in the Sitecore documentation, although these should hopefully be updated on the Sitecore docs site soon.

I’m going to talk here about doing this via an Azure Key Vault rather than the Windows Key Store, since most Sitecore developers are familiar with using MMC and the Windows certificate store. Plus many production deployments will be on Azure PaaS so the Key Vault is a logical choice, but the steps have some commonality which hopefully will be apparent and useful in either case. Also, there are a number of ways to do this but I’m going to outline the approach that I used. For example, you could use a certificate to create your Column Master Key if you prefer. I ran into issues with the PowerShell approach outlined on various Microsoft documentation pages so I opted for the more manual approach outlined below. If you get the PowerShell approach to work, then please share.

Disclaimer: I am not a SQL Server DBA nor a Security Administrator. I accept no responsibility for damage or data loss caused by following these instructions. Please test this approach in a safe environment before performing changes to production data.

Step 1 – create a key in Azure KeyVault

Firstly you’ll need a KeyVault in your Azure subscription. Just add a Key Vault resource from the portal:

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Then create a key by clicking Generate/Import:

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Give the key a name and choose the key type and key size:

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You should now have a key in your key vault:

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Step 2 – Assign appropriate permissions to your user to access and use the key

Now comes a REALLY IMPORTANT STEP that is currently undocumented. You must ensure that you have sufficient rights to create and use the keys. If you run into problems later when creating the Column Encryption Keys then come back to this step.

Click on Access policies and then select your Azure portal user (in my case as per below):

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The permissions blade will then open and you must select the policies as per below:

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The bottom 4 cryptographic operations will probably not be checked – you absolutely need the following operations: Unwrap Key, Wrap Key, Verify, Sign. Without those you will encounter some, ahem, cryptic error messages.

Finally click OK to exit the permissions blade and then make sure you click SAVE on the Access Policies screen that is displayed after that. It’s an easy step to miss and it will cause you grief later on if you forget to save.

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In Part 2, I will cover how to create Column Master Keys and Column Encryption Keys based on the new key we have just created. In subsequent posts I will cover the creation of Application Registrations and Client Secrets, assigning permissions, configuring xConnect, and encrypting the data, as well as some other related topics.