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Category: Security

skip-2.0 and SQL Server Security

Published 2019-10-28 by Kevin Feasel

K. Brian Kelley has the lowdown on skip-2.0:

Problem
I’ve read recently that there’s a new piece of malware that’s been named skip-2.0 and it targets SQL Server. What exactly is it, where did it come from, and how do I protect myself against it?

Solution
This new piece of malware, skip-2.0, does target SQL Server. Specifically, it targets SQL Server versions 11 and 12, which correspond to the names SQL Server 2012 and SQL Server 2014 respectively. Therefore, if you’re only running SQL Server 2016 or higher, you’re not affected by skip-2.0 (yet another reason to upgrade).

Read on to learn how it works and how you can protect against it.

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JDBC Resource Pools and Kerberos

Published 2019-10-23 by Kevin Feasel

Guy Shilo has a tip for us around JDBC connectivity when your Hadoop cluster is configured for Kerberos:

This is a quick tip about connecting to Hive or Impala via JDBC.

Accessing hive or impala using their JDBC driver is very convenient. Client programs s like beeline or Jetbrains DataGrip use it as the main way of accessing Hive/Impala and many people also use it in their own written programs.

Things get a little trickier when the cluster is kerberized. In this case you should add few extra parameters to the JDBC connect string.

Read on to see what to do.

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PowerApps Security

Published 2019-10-22 by Kevin Feasel

Jason Bonello gives us some tips on PowerApps security:

Depending on how the backend is set up, the tables having these sensitive data might be in the same database. For example, ERP solutions can have Company Accounts data, Customer related data and Inventory related data all in the same database, maybe under different schemas – but still part of the same database.

Now let’s say we are about to create a PowerApps solution to maintain Customer information. However, as part of the organization policy, this information should not be shared across other departments apart from the intended users.

Read on for some ideas of how to limit the risk of data exposure.

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Mapping Usernames within the Power BI Gateway

Published 2019-10-15 by Kevin Feasel

Jeff Pries takes us through a difficult scenario:

With some data sources, such as Analysis Services, you want to pass the username of the person running the report back to the server executing the query (such as in a Row Level Security configuration). Adam Saxton of Guy in a Cube does a great job of explaining how this works at a high level in the video linked here.

In the video, Adam mentions that if our Power BI login does not match a UPN in our local Active Directory, then the lookup will fail…which is a problem if you just don’t have the option of having your Power BI login match a UPN in your local Active Directory and don’t want to manage static user mappings over time. The following will cover a method of allowing the lookup to use a different Active Directory property, such as “mail” to perform the matching.

Read on for the steps.

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Tracking Security Changes with the Default Trace

Published 2019-10-09 by Kevin Feasel

Jack Vamvas shows how we can use the default trace with SQL Server to find security-related events:

Question: There were some recent user security changes on a SQL Server login user account. Is there a way to grab this information – via the default trace? I haven’t got a dedicated Extended events monitor set up – so I’m relying on the default trace . Management want to understand the details related to this security change. 
 
Answer: It is possible to report on security changes administered on SQL Server via the default trace. In fact – it’s excellent – except if the default trace configuration is set up to rollover the files.

Read on to see how.

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Bulk Removing Reshare Permissions in Power BI

Published 2019-10-08 by Kevin Feasel

Gilbert Quevauvilliers takes us through bulk changing dataset permissions in Power BI:

Whilst this sometimes is what is required, I always suggest to people to remove this option and rather manage it by exception.

If you do leave this option enabled, it means if I had to share a report with Bob, Bob would then be able to reshare the report with someone else. This could potentially lead to other people gaining access to a report or data that they should not see.

Fortunately, I found a way to quickly remove the reshare option in the Power BI Service.

Click through to see how it’s done.

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Mitigating SQL Injection with SQL Server 2019

Published 2019-10-08 by Kevin Feasel

Grant Fritchey is sick of SQL injection:

Instead, let’s talk about some of the common vectors of SQL Injection. Obviously, building and executing strings is the biggest issue. Appropriate use of parameters will do more to the fix the problem than almost any other step. However, it’s also enhanced by bad code on the front-end which doesn’t appropriately clean the data, inappropriate error handling, bad security, bad data isolation, and more.

The keys to the attack are to get back a few bits of information, usually in error messages in the case of a normal attack, or, through the use of the WAITFOR command in a blind attack (for more detail, I’m talking about this stuff at the PASS Summit). Getting error messages with information about the database makes it easier for me to hack your system (if I was evil). Knowing that I have a SQL Injection vector through the WAITFOR command helps me target appropriate systems (if I was evil).

For the most part, SQL injection isn’t a SQL problem—it’s an application problem (save for the case when you generate dynamic SQL and concatenate in input parameters). SQL Server-based solutions will only do a little bit; fixing the app code is the best answer.

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Listing Windows Users with Powershell

Published 2019-09-27 by Kevin Feasel

Jack Vamvas shows us how we can use Powershell to list Windows users in an Active Directory group:

Question: How can I use Powershell to list out Windows users? Are there Powershell cmdlets which can report on Windows users ?
Answer: There are “out of the box” Powershell cmdlets which will support the requirement . How you apply the powershell cmdlets will depend on how much detail is required.

Jack has a few examples here as well.

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Troubles with Dropping Logins

Published 2019-09-27 by Kevin Feasel

Pamela Mooney takes us through a scenario involving dropping a user and login, and some of the difficulties which might arise:

I had to obscure a lot, but the bottom query results correlate to the top results.  The first line of the bottom query results show the grantor of the permissions, and the bottom line is the grantee.  In this case, a login was explicitly denied impersonation on a server role.  I’m using this example because it is really quirky to fix.  Most often, you’ll just reverse the permissions, using pretty standard syntax. Even easier, right click on the login, go to the “Securables” tab, and remove the permissions.  However, if you are a fan of the TSQL approach, this one is not so straightforward, so it’s a good one to show.  

Click through for a demonstration.

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Why Root Containers are Troublesome

Published 2019-09-19 by Kevin Feasel

Andrew Pruski explains to us why it can be bad to have a container user running as root:

Recently I noticed that Microsoft uploaded a new dockerfile to the mssql-docker repository on Github. This dockerfile was under the mssql-server-linux-non-root directory and (you guessed it) allows SQL Server containers to run as non-root.

But why is running a container as root bad? Let’s run through an example.

Just as with physical devices and VMs before them, Docker containers can do a lot of damage if you’re logged in as root.

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