Excel Services Security Best Practices Authentication And Accounts
When you use Excel Calculation Services to open up Excel workbooks, they should be stored in the SharePoint Sever 2010 content database. This is due to the fact that the SharePoint Foundation 2010 will maintain the access control list for the files. You can also open workbooks from UNC paths or HTTP websites with the use of Excel Calculation Services. However, it is best if you use the SharePoint Server 2010 content database when you want to store workbooks. The authentication for user access for any SharePoint portal site has to be performed with the SharePoint Foundation 2010. This is the default that will be used for the Integrated Windows authentication too. Excel Services Applications also support generic forms based authentication. Yet you will need to configure SharePoint Foundation 2010 if you want to use such generic forms based authentication.
Through claims authentication you will be able to improve security so that you can authenticate your farms, Office Business Applications, and Share Point services from various environments. With the use of Excel Service Application you can use claims based authentication for the various scenarios relating to deployment. It doesn’t matter if you are using a single server or a farm environment. Plus, the authorization and authentication of users in regards to content and resources is going to be better secured within in SharePoint Server 2010 when you have claims based authentication in place.
There can be embedded data in the workbooks that connects and links to other files. All of that information is stored in the data connection libraries. When you refresh the embedded direct data connection may be used as a method of sending a query for data to the data connection library. It can also be used to get a query to the .odc file. This contains information for the connection as well. If you want to configure the Excel Services Application to external data sources you have to choose a setting in the External Data section of the Excel Services Add Trust file Location page. This is on the SharePoint Central Administration web application.
In order to configure administrative settings for Excel Services Application you need to refer to the Manage Excel Services Authentication. The deployments of farms that are intertwined with connections are going to use SharePiont Server 2010 claims based authentication. The Excel Calculation Services will retrieve the connecting information. There are credentials in place to store or integrate the data. All of those connections have credentials that can be used with claims based authentication. The deployments can be scaled when you have multiple servers in place.
If you are talking about deployment for a standalone server, then you need to rely on claims based authentication. When you have a data connection associated with a workbook that is opened in Excel Calculation Services it is best to used stored credentials. That will result in Excel Calculation Services to retrieve the credentials it needs for validation. From there those credentials will be used to authenticate the data source. Only then will the data connection be successfully established.
There are three types of data authentication that are supported by Excel Services Applications. They include:
- Integrated Windows
- Secure Store Service
It is recommended that you use Kerberos for the security configuring with Integrated Windows authentication. This is because SharePoint Server 2010 relies on a claims based authentication. All of the Excel Services Applications are also claims based. You will find that Integrated Windows authentication is exclusively in place for SharePoint Server 2010 and IIS Authentication Settings. With the use of Secure Store Service authentication a user is able to access multiple resources from various systems. They are able to do so without the need for providing their credentials to be authenticated more than once. With SharePoint 2010 the Secure Store Service includes a Window service and a database of secured credentials. The use of the plug in functions for the Secure Store Service, there is the ability to introduce the Secure Store Service provider of your choice with the Excel Services Application. It is important to note that the SharePoint Server 2010 also includes a Secure Store Service provider that is able to successfully work with Excel Services Application.
With any Secure Store Services though that you select to use with Excel Services Application, there will be credentials in place. The credential type should be in place with both Windows and other alternatives. That will allow the Excel Services Application to successfully use the Secure Store Service data base in order to authenticate before connecting and to be able to retrieve credentials. Individual mapping as well as group mapping is supported through SharePoint Server 2010. The Secure Store Service offers a set of credentials that will be used for the Application ID’s for all of the resources in the SharePoint Server 2010 Secure Store Service database.
In regards to individual mapping, there is a secure layer that will validate the credentials of a user against multiple listings for Application ID’s. This type of mapping can be useful if you need to have the log in information for an individual before they can gain access to any types of resources which are shared.
Group mapping is more commonly used though. This includes a secure layer that checks for group credentials compared to those of multiple domains. However, each user has a set of credentials that can be unique with the Application ID’s. You will find that group maps are easier to maintain than those that are individual. You will also find that you get better overall performance.
If you want to enable the Secure Store Service function for SharePoint Server 2010 you will need to create a new Secure Store Service. This takes place in the SharePoint Central Administration website.
You have the option of selecting none as the type of authentication method you would like in place as you deploy the Excel Services Application. When this occurs an inbound connection will be used to connect to the database that has been specified in the string. It is important to understand that the connection strings are passed to the database provider. They aren’t part of the Excel Services Application. When you have connection strings in place, they can specify that a requirement that has to be present is Integrated Windows Authentication. These connection strings are also able to contain the specific password and user name for a given user. When that is the case Excel Services Application will require what is equivalent to an unattended service account for the authentication method.
Should the provider of the database make the determination that the string for the connection has Integrated Windows Authentication, then the database can authorize access for that user. The connection will be established through the use of a security context relating to an unattended account.
A type of privileged account that is encrypted for security is the Unattended Service Account. This has been discussed in several other posts. The Secure Store Service for it will have credentials that are found in Excel Calculation Services. This makes it possible to replicate what has been established for a secure data connection to be completed. This is the process when the environment isn’t one which is Windows based. If the Unattended Service Account isn’t configured, then the data connection will fail. This is because the Secure Store Service can’t be authenticated from such an environment and though this method for authentication. The process of replicating the Unattended Service Account protects what is found in the SharePoint Server 2010 database.
It can’t be accessed from unauthorized connections that are using Excel Calculation Services for the task of opening external data connections. An Unattended Service Account results in external data queries operating under a low permissions account for security. This is opposed to it operating from the security of the Excel Calculation Services. It is possible to configure the Unattended Service Account as a domain account or a local computer account. It is important to make sure the configuration is the same for all of the application servers that run Excel Calculation Services. These credentials will always be cached for each workbook session. When a workbook is loaded through the data connection using an Unattended Service Account, the account will be obtained from the Secure Store that was used. The credentials won’t be cached globally. It is possible to restrict the permissions of the Unattended Service Account so that only logging in can be accomplished on a given network.