MS Access column-level security - sql

I need to be able to restrict access to a specific columns in my database.
The user cannot make a SQL view of columns A and D or C and D but are allowed to for B and D.
Any suggestions and help would be greatly appreciated.

The Access Database Engine is not designed to manage security in the way that you have described*. You could restrict access to certain items at the application level, but users would still be able to open the back-end database file directly and see things that you apparently don't want them to see.
If this sort of security really is important then you should use a client/server back-end database and set permissions on various objects at the database level. For example, any edition of Microsoft SQL Server, even the Express Edition, can do this.
*(The older Access .mdb database format supported user-level security, but that security model has been deprecated.)

As a general approach for relational databases, I would just suggest a view creation (which would contain only columns available for particular users) and then just allowing access to the views and forbidding access to the tables.

Related

SQL - is it bad practice to give Read-Only access to the entire company?

I work in my companies small IT department. I have been creating automation via VBA in Excel to pull data from SQL and put it into Excel, then dynamically format and summarize the data. The issue I am running into is the IT department does not want to give anyone outside the IT department SQL Read-Only Access. They view SQL as a privilege not a right...even if it is only Read-Only. They claim security reasons.
Just to be clear, we are NOT installing SQL on these peoples' computers nor do they have the technical understanding on how to write queries. Also, they can already view all the information on the front-end website.
I currently have to specify which database and which tables they can have access to and it takes about 1-2 weeks to give them access (they drag their feet doing the requests).
I am not trying to vent, I am actually wondering do they have a legit concern about security and is this actually a best practice on their part?
The worst thing that could happen is a user knows just enough to connect MS Access to the database, write some poor queries, and grind everything to a halt. You should always have non-IT users access data in a safe, structured way. Especially if this database is a transactional one, and not a reporting database.
Sure, they can access all the data per business process. So then, create a nice, safe query to read all the data and dump it to Excel - if that's what the users want.
Otherwise, IT-created queries - preferably in Stored Procedures - should be reading the data and presenting it to the users.
So it's not a security issue per se. It's more an issue of "we don't want non-IT users getting crafty and bringing down the database with poorly written queries."
I believe the connection properties to the SQL server is embedded in your VBA code, as long as the code is not visible to the user then there is no way they can query the SQL server directly.
Sounds like you need an SQL read only service account which you can use for Query connections. Create an Excel data connection that has the security details to connect to SQL, then your VBA hooks into that data connection.

GRANT Database Permissions for specific tables and the validity of this as a security practice?

my question is rather simple.
Can i grant permissions on a database table wise? something in the lines:
User Management has permission to select, update, insert and delete on table Projects
User Supervisor has permission to select, update, insert on table Projects
User Colaborator has permission to select on table Projects
If so, I could set up a system to create database users based on the levels of access of my application, much like the examples above.
Is it a valid mechanism to use this to secure a application?
is it worth on a real world application?
i've used PHP with Oracle and MySQL, but I'm look for a database/language agnostic answer, but any example would be useful.
pushing my luck a bit, what about per record permission granting?
also, what about table schemas, are they a more acceptable then table based permissions?
The main problem with using database security would be that you need separate connections for each user rather than being able to use a "service user" for the connection from your application server to your DB server. That would mean that you would no longer be able to use database connection pooling have to "connect" and "disconnect" from the database for every user request, which is not very efficient as connections are relatively expensive.
Having said that, there is good reason for using separate users in the database, such as DATA_USER (which the application server connects as) and DATA_OWNER (which owns all the tables but is used only for DB maintenance) and then only give DATA_USER the permissions that it needs to, e.g. only select on a lookup table. By separating DATA_USER and DATA_OWNER you can add an additional level of confidence that your application won't issue DDL commands (e.g. dropping a table).
Answer to part 1:
Yes as long as you handle the responses correctly.
Part 2:
It's not as good as implementating security in the application layer, as most applications will need flexibility in the solution (what if you want a user to get increased privledges, have to code in lots of alter/deny/grant scripts)
Part 3: (Speaking from purely MSSQL) Row-level permissions aren't possible. Create custom views for this purpose.

SQL 2005 Security - Users: What are they used for? (and other various questions)

I am not a DBA and so dont really know anything about SQL 2005 security settings, etc. I am attempting to set up an empty copy of our database by generating the full database from SQL Management Studio generated scripts. Unfortunately I don't know what many of the options do and the MSFT documentation of this processes isn't great.
There is an option to generate script for Schemas, Tables, Views and Users. It is the users I am confused about, because I don't understand how they affect the usage of the database. We have some developers in the team who are in this list and some who are not, yet everyone can do anything on the database, at least when they are hosting it on their own machines.
Do I need to keep these Users in my new generated database and what do they do?
We also have a dbo User who is a db_owner and owns many of our schemas. What is this dbo User? What is the significance of a user Owning Schemas? We use Schemas as "namespaces" to group logically related tables in our database but I take it there is more to them than that?
There is also a username tied to this dbo User, its the windows NT login of one of our developers, but he doesn't have his own User object in the list...is there any significance to this? Is this a bad thing?
Other Users are guest, INFORMATION_SCHEMA and sys, but I think these are all defaults?
Sorry but I am a SQL admin ignoramus and usually left these things to the DBA in my previous job!
Thanks for any help.
Do I need to keep these Users in my new generated database and what do they do
The answer is it depends. If your applications use a mixed mode authentication then you will need the user accounts created in SQL. If you use windows authentication (and it sounds like you are) then you might not need them.
What is the significance of a user Owning Schemas?
In SQL Server 2005 all schemas must be owned by a user. Schemas can be used to group functionality but they can also be used to group security. For example a user account may only have access to a specific schema (or multiple schemas).
Hopefully that helps answer some of your questions

SQL Server how to control access to data between clients on the same database

We have a system with 2 clients (which will increase). These two clients connect to the same server/database, however neither should be able to see the others sensitive information. There is however some shared non sensitive information.
There is also an administrative department who does work on behalf on both of the clients. They are allowed to see all sensitive data.
We currently handle this by holding a ClientID against the tables in question and with a mixture of views and queries check against the ClientID to control access for each client.
I want to move to a consistent handling of this in our system e.g. all views, or all queries, however I just wondered if there was perhaps an easier/ better Pattern than using views to handle this situation?
We're using Sql Server 2005 however upgrade to 2008 is possible.
Cheers
the most logical way is to have (indexed) views filtered by what each user can see.
add read/write permisisons to each client for their views. admins access the tables directly.
but it looks to me that each client is a logicaly separated entity form the others.
if that's the case you might consider having 1 db per client and 1 db for shared stuff.
admins can access everything, each client cas only access it's own db and read from common db.
a 3rd option is to look into schemas and separate your clients there.

What good are SQL Server schemas?

I'm no beginner to using SQL databases, and in particular SQL Server. However, I've been primarily a SQL 2000 guy and I've always been confused by schemas in 2005+. Yes, I know the basic definition of a schema, but what are they really used for in a typical SQL Server deployment?
I've always just used the default schema. Why would I want to create specialized schemas? Why would I assign any of the built-in schemas?
EDIT: To clarify, I guess I'm looking for the benefits of schemas. If you're only going to use it as a security scheme, it seems like database roles already filled that.. er.. um.. role. And using it a as a namespace specifier seems to have been something you could have done with ownership (dbo versus user, etc..).
I guess what I'm getting at is, what do Schemas do that you couldn't do with owners and roles? What are their specifc benefits?
Schemas logically group tables, procedures, views together. All employee-related objects in the employee schema, etc.
You can also give permissions to just one schema, so that users can only see the schema they have access to and nothing else.
Just like Namespace of C# codes.
They can also provide a kind of naming collision protection for plugin data. For example, the new Change Data Capture feature in SQL Server 2008 puts the tables it uses in a separate cdc schema. This way, they don't have to worry about a naming conflict between a CDC table and a real table used in the database, and for that matter can deliberately shadow the names of the real tables.
I know it's an old thread, but I just looked into schemas myself and think the following could be another good candidate for schema usage:
In a Datawarehouse, with data coming from different sources, you can use a different schema for each source, and then e.g. control access based on the schemas. Also avoids the possible naming collisions between the various source, as another poster replied above.
If you keep your schema discrete then you can scale an application by deploying a given schema to a new DB server. (This assumes you have an application or system which is big enough to have distinct functionality).
An example, consider a system that performs logging. All logging tables and SPs are in the [logging] schema. Logging is a good example because it is rare (if ever) that other functionality in the system would overlap (that is join to) objects in the logging schema.
A hint for using this technique -- have a different connection string for each schema in your application / system. Then you deploy the schema elements to a new server and change your connection string when you need to scale.
At an ORACLE shop I worked at for many years, schemas were used to encapsulate procedures (and packages) that applied to different front-end applications. A different 'API' schema for each application often made sense as the use cases, users, and system requirements were quite different. For example, one 'API' schema was for a development/configuration application only to be used by developers. Another 'API' schema was for accessing the client data via views and procedures (searches). Another 'API' schema encapsulated code that was used for synchronizing development/configuration and client data with an application that had it's own database. Some of these 'API' schemas, under the covers, would still share common procedures and functions with eachother (via other 'COMMON' schemas) where it made sense.
I will say that not having a schema is probably not the end of the world, though it can be very helpful. Really, it is the lack of packages in SQL Server that really creates problems in my mind... but that is a different topic.
I tend to agree with Brent on this one... see this discussion here. http://www.brentozar.com/archive/2010/05/why-use-schemas/
In short... schemas aren't terribly useful except for very specific use cases. Makes things messy. Do not use them if you can help it. And try to obey the K(eep) I(t) S(imple) S(tupid) rule.
I don't see the benefit in aliasing out users tied to Schemas. Here is why....
Most people connect their user accounts to databases via roles initially, As soon as you assign a user to either the sysadmin, or the database role db_owner, in any form, that account is either aliased to the "dbo" user account, or has full permissions on a database. Once that occurs, no matter how you assign yourself to a scheme beyond your default schema (which has the same name as your user account), those dbo rights are assigned to those object you create under your user and schema. Its kinda pointless.....and just a namespace and confuses true ownership on those objects. Its poor design if you ask me....whomever designed it.
What they should have done is created "Groups", and thrown out schemas and role and just allow you to tier groups of groups in any combination you like, then at each tier tell the system if permissions are inherited, denied, or overwritten with custom ones. This would have been so much more intuitive and allowed DBA's to better control who the real owners are on those objects. Right now its implied in most cases the dbo default SQL Server user has those rights....not the user.
I think schemas are like a lot of new features (whether to SQL Server or any other software tool). You need to carefully evaluate whether the benefit of adding it to your development kit offsets the loss of simplicity in design and implementation.
It looks to me like schemas are roughly equivalent to optional namespaces. If you're in a situation where object names are colliding and the granularity of permissions is not fine enough, here's a tool. (I'd be inclined to say there might be design issues that should be dealt with at a more fundamental level first.)
The problem can be that, if it's there, some developers will start casually using it for short-term benefit; and once it's in there it can become kudzu.
In SQL Server 2000, objects created were linked to that particular user, like if a user, say
Sam creates an object, say, Employees, that table would appear like: Sam.Employees. What
about if Sam is leaving the compnay or moves to so other business area. As soon you delete
the user Sam, what would happen to Sam.Employees table? Probably, you would have to change
the ownership first from Sam.Employees to dbo.Employess. Schema provides a solution to
overcome this problem. Sam can create all his object within a schemam such as Emp_Schema.
Now, if he creates an object Employees within Emp_Schema then the object would be
referred to as Emp_Schema.Employees. Even if the user account Sam needs to be deleted, the
schema would not be affected.
development - each of our devs get their own schema as a sandbox to play in.
Here a good implementation example of using schemas with SQL Server. We had several ms-access applications. We wanted to convert those to a ASP.NET App portal. Every ms-access application is written as an App for that portal. Every ms-access application has its own database tables. Some of those are related, we put those in the common dbo schema of SQL Server. The rest gets its own schemas. That way if we want to know what tables belong to an App on the ASP.NET app portal that can easily be navigated, visualised and maintained.