Guidelines for using the TRUSTWORTHY database setting in SQL Server

In an Internet service provider (ISP) environment (for example, in a web-hosting service), each customer is permitted to manage their own database and is restricted from accessing system databases and other user databases. For example, the databases of two competing companies could be hosted by the same ISP and exist in the same instance of SQL Server. Dangerous code could be added to a user database when the database was attached to its original instance, and the code would be enabled on the ISP instance when the database was deployed. This situation makes controlling cross-database access crucial.

 

If the same general entity owns and manages each database, it is still not a good practice to establish a "trust relationship" with a database unless an application-specific feature, such as cross-database Service Broker communication, is required. A trust relationship between databases can be established by enabling cross-database ownership chaining or by marking a database as trusted by the instance by using the TRUSTWORTHY property. Theis_trustworthy_on column of the sys.databases catalog view indicates whether a database has its TRUSTWORTHY bit set.

Best practices for database ownership and trust include the following:

• Have distinct owners for databases. Not all databases should be owned by the system administrator.
• Limit the number of owners for each database.
• Confer trust selectively.
• Leave the Cross-Database Ownership Chaining setting set to OFF unless multiple databases are deployed at a single unit.
• Migrate usage to selective trust instead of using the TRUSTWORTHY property.

The following code sample can be used to obtain a list of databases that have the TRUSTWORTHY bit ON and whose database owner belongs to the sysadmin server role.

SELECT SUSER_SNAME(owner_sid) AS DBOWNER, d.name AS DATABASENAME

FROM sys.server_principals r

INNER JOIN sys.server_role_members m ON r.principal_id = m.role_principal_id

INNER JOIN sys.server_principals p ON

p.principal_id = m.member_principal_id

inner join sys.databases d on suser_sname(d.owner_sid) = p.name

WHERE is_trustworthy_on = 1 AND d.name NOT IN ('MSDB') and r.type = 'R' and r.name = N'sysadmin'

You can run the following query to determine the TRUSTWORTHY property of the MSDB database:

select name, TrustWorthySetting =
case is_trustworthy_on
when 1 then 'TrustWorthy setting is ON for MSDB'
ELSE 'TrustWorthy setting is OFF for MSDB'
END
from sys.databases where database_id = 4 

If this query shows that the TRUSTWORTHY property is set to OFF, you can run the following query to set the TRUSTWORTHY property to its default value.

ALTER DATABASE MSDB SET trustworthy ON
go

The following table provides more information on the products or tools that automatically check for this condition on your instance of SQL Server and the versions of the SQL Server product that the rule is evaluated against.