TMA-MSSQL2022-3.2
Ensure CONNECT permissions on the 'guest' user is Revoked within all SQL Server databases
Description
Remove the right of the guest user to connect to SQL Server databases, except for master, msdb, tempdb, and, on AWS RDS instances, rdsadmin. A login assumes the identity of the guest user when a login has access to SQL Server but does not have access to a database through its own account and the database has a guest user account. Revoking the CONNECT permission for the guest user will ensure that a login is not able to access database information without explicit access to do so.
How it is checked
Audit method: SQL query
sqlcmd -b -h -1 -W -Q "SET NOCOUNT ON; DECLARE @n int = 0, @k int, @db sysname, @s nvarchar(max); DECLARE c CURSOR LOCAL FAST_FORWARD FOR SELECT name FROM sys.databases WHERE state = 0 AND HAS_DBACCESS(name) = 1 AND name NOT IN ('master','tempdb','msdb'); OPEN c; FETCH NEXT FROM c INTO @db; WHILE @@FETCH_STATUS = 0 BEGIN SET @s = N'USE ' + QUOTENAME(@db) + N'; SELECT @k = COUNT(*) FROM (SELECT permission_name FROM sys.database_permissions WHERE grantee_principal_id = DATABASE_PRINCIPAL_ID(''guest'') AND state_desc LIKE ''GRANT%'' AND permission_name = ''CONNECT'') AS x;'; EXEC sp_executesql @s, N'@k int OUTPUT', @k = @k OUTPUT; SET @n = @n + @k; FETCH NEXT FROM c INTO @db; END; CLOSE c; DEALLOCATE c; SELECT @n;"- Expected output
0
How it is fixed
Fix method: Guidance or infrastructure patch
The following code snippet revokes CONNECT permissions from the guest user in a database. Replace <database_name> as appropriate: USE <database_name>; GO REVOKE CONNECT FROM guest;
Properties
- Operating systems
- Any
- Tags
- access-controlmssqlsqlserver-2022
- Reference
- CIS Microsoft SQL Server 2022 Benchmark v1.3.0 - 3.2 Ensure CONNECT permissions on the 'guest' user is Revoked within all SQL Server databases
Check this host
Run this on a machine you are allowed to audit. The scan is read-only.
tmaegis scan --target mssql