How can you use EXECUTE AS CALLER to secure T-SQL stored procedures?

1 What is EXECUTE AS CALLER?

EXECUTE AS CALLER is an option that you can specify in the definition of a T-SQL stored procedure, using the syntax CREATE PROCEDURE ... WITH EXECUTE AS CALLER . This option means that the stored procedure will run under the security context of the user who calls it, rather than the owner of the stored procedure or a specified user. This means that the stored procedure will inherit the permissions and roles of the caller, and will be subject to the same security checks and restrictions as the caller. This option can help you prevent unauthorized access to your stored procedures, as well as prevent privilege escalation or impersonation by malicious users.

2 How does EXECUTE AS CALLER differ from other EXECUTE AS options?

There are other EXECUTE AS options that you can use in T-SQL stored procedures, such as EXECUTE AS OWNER, EXECUTE AS SELF, or EXECUTE AS 'user_name'. These options mean that the stored procedure will run under the security context of the owner of the stored procedure, the current user, or a specified user, respectively. These options can be useful for granting permissions to the stored procedure that the caller may not have, or for restricting the permissions of the stored procedure to a lower level than the caller. However, these options also have some drawbacks, such as requiring additional permissions to use, creating potential security risks if the owner or the specified user is compromised, or breaking the ownership chain of the stored procedure and its dependent objects.

3 How to use EXECUTE AS CALLER effectively?

To use EXECUTE AS CALLER effectively, you should design your stored procedures to perform only the necessary tasks and avoid accessing objects that the caller may not have permissions to access. Utilizing schemas to organize your database objects and assign permissions to them can help maintain the ownership chain of your stored procedures and their dependent objects. Additionally, signing can grant additional permissions to your stored procedures without breaking the ownership chain or compromising the security context of the caller. These best practices can be used to leverage the benefits of EXECUTE AS CALLER and ensure the integrity and confidentiality of your data.

4 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?