Group authentication oddity

Question

Group authentication oddity

wmt

SSChasing Mays

Points: 602
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March 15, 2016 at 7:06 am

#309116

Very confused with some security behavior I'm seeing.
I've restored a database from SQL 2008 to SQL 2012.
Within the Database Users, there was a previous Windows group which had db owner. It doesn't exist on the SQL 2012 server.
I've created a new group which only has Read access. Added this to the server and database.
So,
Within the database, I've got:
One Windows group with db owner access which doesn't have a server login.
One Windows group with Read access which does have a server login.
It's the same users in both groups. There aren't any embedded groups i.e. groups within groups or anything like that.
The effective permissions the users have is db owner.
If I remove the old group, they revert back to Read access only.
I would've thought that SQL would've ignored the old Windows group completely, given that it doesn't have a server login.
It's not a Contained database - even partial.
Compatibility level is SQL 2008.
Is this expected behavior?

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Lowell SSC Guru Points: 323518 More actions · Answer 1

yes, it's expected behavior when we are talking about Windows groups.

you just have to take into consideration the situations you are seeing here: multiple groups, and the cumulative inheritance of permissions that can provide.

Lowell

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wmt SSChasing Mays Points: 602 More actions · Answer 2

thanks for that.

I'd always presumed that a windows group named at a database level needed a corresponding server login, regardless of what other access the user had to the instance via other groups.