SQL Server offers an option to encrypt the code of your modules when using the 'WITH ENCRYPTION' syntax. This allows to hide/obfuscate the modules' code and thus keep away from prying eyes. It's often used to protect business rules since it allows you to protect some intellectual property. In this article, we will look at how to recover the code from encrypted modules.

What is a module in SQL Server?

In the SQL Server world, a module consists of a block(s) of T-SQL statements that make up a stored procedure, a function, a trigger or a view definition.

Which modules can be encrypted?

These are the objects' types that can be encrypted:

• P - Stored procedures
• V - Views
• TR - Triggers
• FN, IF, TF - Functions

On the other hand, the following types also appear in sys.sql_modules, but they can't be encrypted:

• RF - Replication-filter-procedure
• R - Rule
• D - Default

You can run the following T-SQL statement to check on sys.sql_modules which objects you have and if they are encrypted or not (the `definition` column has the `NULL` value).

SELECT sm.object_id, o.name, o.type, sm.definition 
  FROM sys.sql_modules sm
    INNER JOIN sys.objects O
       ON sm.object_id = o.object_id

What happens to the module text when we specify WITH ENCRYPTION?

From the CREATE PROCEDURE documentation, WITH ENCRYPTION:

...SQL Server converts the original text of the CREATE [enter object type here] statement to an obfuscated format. The output of the obfuscation is not directly visible in any of the catalog views in SQL Server. Users who have no access to system tables or database files cannot retrieve the obfuscated text. However, the text is available to privileged users who can either access system tables over the DAC port or directly access database files. Also, users who can attach a debugger to the server process can retrieve the decrypted procedure from memory at runtime. For more information about accessing system metadata, see Metadata Visibility Configuration.

If you want to understand the Internals of With Encryption make sure you read Paul White’s (b | t) blog post.

A Story

I would like to share a story about encrypted modules. I inherited a database with encrypted modules but without native scripts. This isn't something that happens too often, however, it can happen and it's not a nice feeling. All of a sudden we inherit a database or a client requests help because they don't have the source code of the modules.

My tool of choice for recovering the code was dbatools.

Choosing a Tool

There are multiple ways to retrieve the decrypted version of an encrypted module. We can use a T-SQL script or other third-party tools. Here are a few that you can use:

• T-SQL
• SQLDecryptor
• dbForge SQL Decryptor
• Invoke-DbaDbDecryptObject command from dbatools PowerShell module

The last one will be our focus in this article. Here I will be focusing on how we can do it at scale and with a couple of different use cases.

If you want to understand how dbatools does it, Sander Stad (b | t) was the person that wrote this dbatools' function and he explains it on his blog post Decrypting SQL Server Objects With dbatools.

Prerequisites

There are a few items you need to follow along with this article.

dbatools

You can install the latest version of the module from the PowerShell Gallery by running the following command:

Install-Module -Name dbatools

You may need administrator privileges to install this module.

DAC

Stands for Dedicated Admin Connection.

The DAC lets an administrator access a running server to execute diagnostic functions or Transact-SQL statements, or to troubleshoot problems on the server, even when the server is locked or running in an abnormal state and not responding to a SQL Server Database Engine connection.

If you want to connect using DAC from a remote server, you need to configure the remote admin connection option as the default is 0 (off).

Using dbatools to check/set the 'remote admin connection' configuration

Get-DbaSpConfigure -SqlInstance "instance1" -ConfigName RemoteDacConnectionsEnabled

If you want to be able to run this from a remote server, the output should say 1 in the 'ConfiguredValue' property. If the output says 0 (zero), you can use dbatools to change it to 1, by doing:

Set-DbaSpConfigure -SqlInstance "instance1" -ConfigName RemoteDacConnectionsEnabled -Value 1

NOTE: In some cases, you may need to restart the instance.

Examples

If you're curious about the steps that are simplified by dbatools, you can visit Paul White's post (referenced before) to see how it's done in T-SQL. I want to say that this is OK if we are talking about a couple of modules. However, that's not the case of our scenario, where we want to decrypt all objects of a specific database.

Let's see how to use dbatools to eliminate hard and repetitive work.

A couple of tests

Before I go through all objects, I decided to start by doing a test by decrypting a single object to check the outcome.

Decrypt a single object on a single database

The following code will decrypt just a single object and output the result to the console

Invoke-DbaDbDecryptObject -SqlInstance "instance1" -Database "WithEncryption" -ObjectName "MySecretSauce"

We can also decrypt more than one object in the same execution

Now that I understand what my outcome is, let's try to decrypt two objects from the same database

Invoke-DbaDbDecryptObject -SqlInstance "instance1" -Database "WithEncryption" -ObjectName "MySecretSauce", "MySecret"

NOTE: If you want to decrypt all encrypted objects that belong to a specific database you just need to omit the `-ObjectName` parameter.

Invoke-DbaDbDecryptObject -SqlInstance "instance1" -Database "WithEncryption"

What if I want to save the results to file?!

Back to my story, I knew that I would like to save a decrypted version of each object. This way we can edit the code and update the module or just to keep a readable copy of it (don't forget to keep it on your versioning tool).

Ultimately, I have decided to do the following:

1. Save a decrypted version of each object as a T-SQL script.

2. Compile SQL scripts but without encryption on a different/same database

Saving results to a local folder

To do so, with dbatools, we just need to define the `-ExportDestination` parameter and indicate to which folder we want to output our decrypted T-SQL code. This command will create a folder for each type of objects, and within and you will find one SQL script per object that was decrypted.

Invoke-DbaDbDecryptObject -SqlInstance "instance1" -Database "WithEncryption" -ExportDestination "d:\temp\"

Compile SQL scripts but without encryption on a different/same database

If you open any of these decrypted files, you will see that the `WITH ENCRYPTION` keywords are there, which means that it will encrypt the code if you run it.

If you want to replace all encrypted (Stored Procedures, for example) version by the decrypted version, you will need to:

1. drop encrypted Stored Procedures objects

2. Comment/remove the `WITH ENCRYPTION`

3. Compile them on the database

To check which stored procedures are encrypted, you can use the Get-DbaDbStoredProcedure

$instance = "instance1"
$database = "myDB"
$SPs = Get-DbaDbStoredProcedure -SqlInstance $instance -Database $database -ExcludeSystemSp | Where-Object IsEncrypted -eq $true
$SPs | Select-Object InstanceName, Database, Schema, Name
# The next line is a comment on purpose to avoid accidents :-). However, it is an option that you can use to DROP the stored procedures
# $SPs | Foreach-object {$_.Drop()}

Here is a script to run the steps two and three:

$instance = "instance1"
$database = "myDB"
$modulesFolder = "D:\temp\$instance\$database\StoredProcedure"
$objectsList = (Get-ChildItem -Path $modulesFolder -Recurse -Filter "*.sql*") | Select-Object -ExpandProperty FullName
foreach ($object in $objectsList) {
  $TSQLcode = (Get-Content -Path $object -Raw) -replace '\bWITH ENCRYPTION\b', ''
  Invoke-DbaQuery -SqlInstance $instance -Database $database -Query $TSQLcode
}

Here we can see that the Stored Procedure is no longer encrypted

Wrapping up

We have seen how we can leverage dbatools PowerShell module to do the hard work for us when it comes to decrypting modules.

This can be useful to recover lost code, make backups even for versioning it.

Hopefully, it is nothing that you will need to use every single day! But, if that day arrives you will be prepared with another tool to make your life easier!

Thanks for reading!