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Category: Security

Stop Using Domain Admin!

Sean McCown has had it with people using Domain Admin accounts as service accounts:

If you paid close attention, you’ll notice the ‘DomainAdmin’ portion of that name.  Yep, you got it right… they were running SSRS under the domain admin account.  The Windows guy thought that it would be too much trouble to manage the permissions and get everything right on all the shares and DBs that it needed to access.

So this is when I pretty much lost it.  These guys were running  SSRS under a domain admin account because they were too lazy to do the right thing.  It’s unthinkable.  There may be some reasonable excuses why you’re not able to change your current security model to something better.  You may even be able to convince me that you’re not just being lazy.  But to actively be lazy about your security isn’t something I’m going to take lying down.  Hey, I know it’s your shop, and I know you can ultimately do whatever you like, but I’m going to make sure you know what you’re doing.

Your SQL Server (and related) service accounts should not be Domain Admin.  Period.  This isn’t one of those “Well, it depends…” types of scenarios; there is no reason ever to use an account with Domain Admin rights as a SQL Server service account, and it is security malpractice to do so.

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Database Role Members

Nate Johnson has a quick demo showing how to add users to database roles:

The “old” method involves calling system stored-procedures, sp_addrolemember and sp_droprolemember, in which you pass the role-name and username.  The “new” method, supported starting with SQL 2012, is to use the command-phrases ALTER ROLE [role] ADD MEMBER [user], and ALTER ROLE [role] DROP MEMBER [user].

Nate shows both methods, so check it out.

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One Surefire Guarantee For Slow Performance

Patrick Keisler troubleshoots an issue where the buffer pool gets flushed each morning:

What is the McShield service? A quick Bing search revealed that it’s one of the services for McAfee VirusScan Enterprise. Could this be the cause? To get a quick look at all the history, I filtered the application log for event IDs: 17890 and 5000. Each time McAfee got an updated virus DAT file, SQL Server soon followed that by paging out the entire buffer pool. I checked the application log on several other SQL Servers for the same event IDs, and sure enough the same events occurred in tandem each morning. I also got confirmation from the security administration team that McAfee is scheduled to check for new DAT files each morning around 8AM. Eureka!

This seems like it could be the cause of our paging, but a little more research is needed. Searching the McAfee knowledge base, lead me to this article about the “Processes on enable” option.

Enabling this option causes memory pages of running processes to get paged to disk. And the example given is “Oracle, SQL, or other critical applications that need to be memory-resident continually, will have their process address space paged to disk when scan Processes On Enable kicks in”. OUCH! So when the McAfee service starts up or it gets a new DAT file, it will page out all processes.

Fortunately, this is a setting you can turn off, and Patrick shows how.

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Dynamic Data Masking

Andrea Allred has been checking out Dynamic Data Masking in SQL Server 2016:

This is a great time to talk about the different masking functions and what they do.  The four types in 2016 are Default, Email, Random and Custom String.

Default – For numeric and binary it will show a “0” For a date it will show 01/01/1900 and for strings it will show xxxx’s (more or less depending on the size of the field).

Email – It will expose the first letter of the email address and the suffix at the end of the email (.com, .net, .edu etc.) For example Batgirl@DC.com  would now be bxxx@xxxx.com.

Random – Number randomly generated between a set range. Kind of like the game, “Pick a number between 1 and 10” but for SQL.

Custom String – Lets you get creative with how much you show or cover and what you use to cover (not stuck with just xxxx’s).

It’s not really a security feature, but it could be useful for protecting sensitive data from snoopers glancing over the shoulder.

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Windows Versus SQL Authentication

Kenneth Fisher looks into why we generally consider Windows authentication more sound than SQL authentication:

A quick search on the internet took me here: Choosing an Authentication Mode. And if you go down to the section Connecting Through Windows Authentication it points out a few important things and then even farther down the section Disadvantages of SQL Server Authentication has a bit more. Then I found a couple of good forum questions here and here. In summary (and only discussing actual security features):

Click through for the answers.  Also read Cristian Satnic’s comments below, as Cristian is correct about wanting to keep passwords hashed instead of encrypted.  Incidentally, Windows passwords aren’t encrypted, either—they’re hashed.

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Securing Azure Storage

Christos Matskas has an article on securing Azure blobs and containers:

All communication with the Azure Storage via connection strings and BLOB URLs enforce the use of HTTPS, which provides Encryption in Transit. You can enforce the use of “Always HTTPS” by setting the connection string like this: “DefaultEndpointsProtocol=https;AccountName=myblob1…” or in SAS signatures, as in the example below:

https://myblob1.blob.core.windows.net/?sv=2015-04-05&ss=bfqt&srt=sco&sp=rwdlacup&se=2016-09-22T02:21:41Z&st=2016-09-21T18:21:41Z&spr=https&sig=hxInpKBYAxvwdI9kbBglbrgcl1EJjHqDRTF2lVGeSUU%3D

To protect data at rest, the service provides an option to encrypt the data as they are stored in the account. There’s no additional cost associated with encrypting the data at rest and it’s a good idea to switch it on as soon as the account is created. There is a one-click setting at the Storage Account level to enable it, and the encryption is applied on both new and existing storage accounts. The data is encrypted with AES 256 cipher and it’s now generally available to all Azure regions and Azure clouds (public, government etc)

There’s some good information here, making it worth the read.

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Blob Auditing For Azure SQL Database

Patrick Keisler shows how to use Blob Auditing with Azure SQL Database to log database activity:

If you have multiple objects or actions to audit, then just separate them with a comma, just like the AuditActionGroups parameter. The one key piece to remember is you must specify all audit actions and action groups together with each execution of Set-AzureRmSqlDatabaseAuditingPolicy. There is no add or remove audit item. This means if you have 24 actions to audit and you need to add one more, then you have to specify all 25 in the same command.

Now let’s run a few queries to test the audit. First, we’ll run a simple select from the Salaries table.

Patrick shows off the UI (which is nice for one-off checking) and also the function sys.fn_get_audit_file(), which you’d probably want to use for automated audit checks.

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Learn SQL Server Security Via E-mails

Chris Bell has announced a free e-mail course for learning the basics of SQL Server security:

Today I am very excited to announce that I have (finally!) launched my email course covering the basics of SQL Server Security.

This has been a lot of work to get a new system in place to make the learning experience a little different. It is like a normal email course, but at the same time it isn’t.

I have been waiting for this for months ever since hearing Chris first talk about it.

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Whither CLR?

Joey D’Antoni is shaking his head about a CLR announcement:

With this is mind, Microsoft has made some big changes to CLR in SQL Server 2017. SQL CLR has always been an interesting area of the engine—it allows for the use of .NET code in stored procedures and user defined types. For certain tasks , it’s an extremely powerful tool—things like RegEx and geo functions can be much faster in native CLR than trying to do the equivalent operation in T-SQL. It’s always been a little bit of a security risk, since under certain configurations, CLR had access to resources outside of the context of the database engine. This was protected by boundaries defined in the CLR host policy. We had SAFE, EXTERNAL_ACCESS, and UNSAFE levels that we could set. SAFE simply limited access of the assembly to internal computation and local data access. For the purposes of this post, we will skip UNSAFE and EXTERNAL_ACCESS, but it is sufficed to say, these levels allow much deeper access to the rest of the server.

Code Access Security in .NET (which is used to managed these levels) has been marked obsolete. What does this mean? The boundaries that are marked SAFE, may not be guaranteed to provide security. So “SAFE” CLR may be able to access external resources, call unmanaged code, and acquire sysadmin privileges. This is really bad.

It’s not the end of the world for CLR, but this is a breaking change.  Read on for more details.

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Generating Homoglyphs In R

Bob Rudis shows how to create homoglyphs (character sequences which look similar to other character sequences) using a few R packages:

We can try it out with a very familiar domain:

(converted <- to_homoglyph("google.com"))
## [1] "ƍ၀໐|.com"

Now, that’s using all possible homoglyphs and it might not look like google.com to you, but imagine whittling down the list to ones that are really close to Latin character set matches. Or, imagine you’re in a hurry and see that version of Google’s URL with a shiny, green lock icon from Let’s Encrypt. You might not really give it a second thought if the page looked fine (or were on a mobile browser without a location bar showing).

Click through for more details, as well as information on punycode.

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