SQL SERVER – Security Conversations and Notes with a DBA

https://blog.sqlauthority.com/2015/03/03/sql-server-security-conversations-and-notes-with-a-dba/

One of the great things about working in Pluralsight is that I get to meet a lot of people (trust me on this). I am lost for words when it comes to how my day job helps me in achieving some of the coolest things presentations at a number of conferences. The Pluralsight booth is always a place where we see some of the great minds from the industry swing by. So in case you get to a conference and get to see a Pluralsight booth, feel free to swing by, take a moment to talk someone out there, I guarantee your time will be well spent.

In one conferences, I vividly remember a conversation from an enthusiast who was coming from the Banking vertical. He attended all my sessions and made sure he caught me at the booth as I spend most of my time there when not delivering sessions. So it was in-between sessions that this gentleman caught me and started asking me a number of questions around security. The whole discussion took close to an hour but I was glad someone was serious enough in trying to understand these basics.

I was super excited and was talking some of the latest and greatest security capabilities of SQL Server 2014 which I explained in my Plurasight Course. But the individual said they were running on a SQL Server 2008 R2. That got me into a fix because I had to rewind my mind to give him recommendations. I kept thinking hard as I starting giving each of the recommendations.

In this blog, let me recollect some of the conversations I had and pen them down for everyone’s reference and most importantly for my reference.

About User Accounts

SQL Server executes as a set of Windows services. SQL Server is required to run under a domain account to interact with network services, to access domain resources such as file shares, or if it uses linked server connections to other SQL Server instances running on other computers in the domain.
When choosing the service account, consider an account with the least amount of privileges needed to do the job and no more.

Using a domain user that is not a member of the Local Administrator group or of the Domain Administrators group will be the best choice for the SQL Server service account.

Some especially sensitive accounts are detailed below:

  • SQL Server Browser is a name resolution service that provides SQL Server instance connection information to clients. If the SQL Server Browser service account is compromised, an attacker can use the permissions associated with the account to expand their control over the Windows environment. It is recommended that the SQL Server Browser service be run under the NETWORK SERVICE account that has the least privileges.
  • Some other security considerations: do not use LOCAL SYSTEM, LOCAL SERVICE, or NETWORK SERVICE as the service account to run MSFTESQL. This could provide an elevation of privileges for the Full-Text Search service.

Prefer Kerberos over NTLM authentication. Kerberos as the default authentication mode for windows connections to SQL Server is possible if client and server are joined in the same domain, or client and server are in different domains, but these two domains are configured as two-way trusts. Furthermore, Kerberos is available by setting the appropriate SPNs. Verify if SQL Server Name (WSFC solution) or Hostname matches the SQL Server service accounts. If so, this could prevent you from defining an SPN on the correct object, because you will get a User and Computer objects with the same name. Refer to Understanding Kerberos and NTLM authentication in SQL Server Connections for further information on setting Kerberos authentication.

As for securing SQL Server roles and permissions, consider the following:

  • The SA account is a well-known and frequent target of malicious users. Disable the account by using the ALTER LOGIN statement. If this is not an option, consider renaming the account by using the ALTER LOGIN statement, as this action can help protect the account. Refer to disabling SA blog.
  • Restrict the membership of the sysadmin fixed server role to logins that use Windows Authentication, assuring a greater protection of SQL Server.
  • If users without sysadmin rights need to perform certain tasks, consider creating proxy accounts. There are two types of proxy accounts, and each relates to a specific set of tasks: the xp_cmdshell proxy and the SQL Agent job proxy.
  • The configuration required by each type of proxy is different, and the way the authorities they give are used is different. If there is a requirement for users without sysadmin rights to run xp_cmdshell, then the xp_cmdshell proxy must be created with the sp_xp_cmdshell_proxy_account Similarly, if there is a requirement for users without sysadmin rights to own SQL Agent jobs, then one or more SQL Agent job proxy accounts must be created.

Though the one hour of conversations spanned a lot of topics and demonstrations on my laptop using MSA account and more. I think this brain dump of the conversation will become a great reference for me if someone asks me these again. Do let me know if you have read about these before in your interactions? Have you implemented these in your environments?

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