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Category: Security

Fun With Meltdown And Spectre

Published 2018-01-05 by Kevin Feasel

Brent Ozar looks at some of the consequences of Meltdown and Spectre for SQL Server DBAs:

That’s because some test results have found big slowdowns when the operating system is patched for Meltdown and/or Spectre. These are big vulnerabilities in the processors themselves, and OS vendors are having to make big changes that aren’t tuned for performance yet. Early benchmarks yesterday were showing 30% drops in PostgreSQL performance, but thankfully newer benchmarks have been showing smaller drops. Red Hat’s benchmarks show 3-7% slower analytics workloads, and 8-12% slower OLTP.

Joey D’Antoni has more:

Will This Impact My Performance?

Probably–especially If you are running on virtual hardware. For workloads on bare metal, the security risk is much lower, so Microsoft is offering a registry option to not include the microcode fixes. Longer term especially if you are audited, or allow application code to run on your database servers, you will need to enable the microcode options.

This will likely get better over time as software patches are released, that are better optimized to make fewer calls. Ultimately, this will need to fixed on the hardware side, and we will need a new generation of hardware to completely solve the security issue with a minimum impact.

Allan Hirt has even more:

There are two bugs which are known as Meltdown and Spectre. The Register has a great summarized writeup here – no need for me to regurgitate. This is a hardware issue – nothing short of new chips will eradicate it. That said, pretty much everyone who has written an OS, hypervisor, or software has (or will have) patches to hopefully eliminate this flaw. This blog post covers physical, virtualized, and cloud-based deployments of Windows, Linux, and SQL Server.

The fact every vendor is dealing with this swiftly is a good thing. The problem? Performance will most likely be impacted. No one knows the extent, especially with SQL Server workloads. You’re going to have to test and reset any expectations/performance SLAs. You’ll need new baselines and benchmarks. There is some irony here that it seems virtualized workloads will most likely take the biggest hit versus ones on physical deployments. Time will tell – no one knows yet.

This will have long-term ramifications.  We’ll deal with them like we’ve dealt with other issues in the past, but it does seem that, at least for now, there will be some performance hit from this.

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Avoid Impersonation And The Trustworthy Flag

Published 2018-01-02 by Kevin Feasel

Solomon Rutzky explains how you can use module signing to avoid the security risks which come with impersonation and setting Trustworthy on:

Admittedly, using Cross-Database Ownership Chaining and/or Impersonation and/or TRUSTWORTHY are quicker and easier to implement than Module Signing. However, the relative simplicity in understanding and implementing these options comes at a cost: the security of your system.

  • Cross-DB Ownership Chaining:
    • security risk (can spoof User / DB-level)
    • db_ddladmin & db_owner users can create objects for other owners
    • Users with CREATE DATABASE permission can create new databases and attach existing databases
  • Impersonation:
    • If IMPERSONATE permission is required:
      • can be used any time
      • No granular control over permissions
    • Cross-DB operations need TRUSTWORTHY ON
    • Need to use ORIGINAL_LOGIN() for Auditing
    • Elevated permissions last until process / sub-process ends or REVERT
  • TRUSTWORTHY:
    • Bigger security risk
      • can also spoof Logins, such as “sa” !
      • If using SQLCLR Assemblies, no per-Assembly control of ability to be marked as either EXTERNAL_ACCESS or UNSAFE; all Assemblies are eligible to be marked as either of those elevated permission sets.

The common theme across all three areas is no control, within a Database, over who or what can make use of the feature / option, or when it can be used.

Read the whole thing.

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Considerations When Using HTTPS For TFS

Published 2017-12-18 by Kevin Feasel

Hamish Watson walks us through what to do when we want to start using a certificate to encrypt Team Foundation Server traffic:

I will assume that you already have TFS setup and are just using HTTP and want to make things a bit more secure with HTTPS. I am also assuming that you will be using port 443 for HTTPS traffic.

To update TFS to use HTTPS you need to do a couple of things:

  1. Have a legitimate certificate installed on the server that you can bind to

  2. Have an IP address on the server and have firewall access setup to that IP address on port 443

But there are a few more steps as well, so click through to see them all.

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Decrypting Always Encrypted Columns In SSMS

Published 2017-12-14 by Kevin Feasel

Monica Rathbun shows how to view Always Encrypted data within Management Studio:

Viewing decrypted data within SQL Server Management Studio (SSMS) is very easy. SSMS uses .NET 4.6 and the modern SQL Server client, so you can pass in the necessary encryption options. SSMS uses the connection string to access the Master Key and return the data in its decrypted format.

First create a new SQL Connection and Click Options to expand the window.

Then go to the Additional Connections Parameters Tab of the login window and simply type column encryption setting = enabled. Then choose Connect.

Click through to see the whole demo.

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Protecting Sensitive Data In Docker

Published 2017-12-12 by Kevin Feasel

Jatin Demla shows how to create Docker secrets:

Managing the password, access tokens and private keys are being tedious in the application. Any small mistakes accidentally expose all the secret information. Even storing such thing in docker images can be easily accessible one should just run the image in the interactive mode container and all your application code is available in containers. Docker provides secrets to protect all secret data.

This blog explains the low-level of storage information as well as secured access to docker secret. so, let’s get started.

Read the whole thing, especially if you’ve gone container-happy.

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API Security: Contrasting Token-Based With Key-Based Security

Published 2017-12-12 by Kevin Feasel

Vincent-Philippe Lauzon contrasts token-based security (like OAuth) with key-based security for locking down APIs:

Instead of giving a nice & neatly formatted pros & cons table where all the pros have a corresponding cons, let’s just discuss the major aspects:  security & complexity.

Basically, in general, OAuth is more secure but more complex for both clients (i.e. consumer) and services.

Why is OAuth more secure?  Relying parties never see credentials & secrets in an OAuth authentication scheme.  They see a token.  Token are revoked after a while ; often minutes, maximum a few hours.

Read on for more.  My preference is OAuth, but it’s not always trivial to set up.

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SQL Vulnerability Assessment

Published 2017-12-12 by Kevin Feasel

Ronit Reger shows off the new SQL Vulnerability Assessment, available in SQL Server 2012 and later:

Not only does VA expose some of the possible security flaws you have in your database system, it also provides remediation scripts to resolve issues within a couple of mouse clicks. In addition, you can accept specific results as your approved baseline state, and the VA scan report will be customized accordingly to expect these values.

Ronit and Alan Yu also mention it being available via the latest version of Management Studio, 17.4:

The VA service runs a scan directly on your SQL database or server. VA employs a knowledge base of rules that flag security vulnerabilities and deviations from best practices, such as misconfigurations, excessive permissions, and exposed sensitive data. The rule base grows and evolves over time, to reflect the latest security best practices recommended by Microsoft.

Results of the assessment include actionable steps to resolve each issue and provide customized remediation scripts where applicable. An assessment report can be customized for each customer environment and tailored to specific requirements. This process is managed by defining a security Baseline for the assessment results, such that only deviations from the custom Baseline are reported.

VA is supported for SQL Server 2012 and later, and can also be run on Azure SQL Database.

This looks like a good reason to upgrade SSMS.

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Data Breaches And Knowledge-Based Authentication

Published 2017-12-08 by Kevin Feasel

Jeff Mlakar summarizes Troy Hunt’s recent congressional testimony:

Lastly, there is a lack of accountability for the breaches. If you collect data about others you are responsible for it. Yet all too often organizations discover years later they suffered a massive data breach and then proclaim to the press that they were hacked by evil doers and caught unprepared.

Then they progress through the stages of data breach grief:

  1. OMG I just read the news and found out we’ve been hacked

  2. Turns out it was 4 years ago

  3. Blame evil hackers while proclaiming innocence as a naive victim

  4. The media turns up the heat – time to blame some systems administrator

  5. Offer your customers credit monitoring

  6. Acceptance

  7. Wait until the next hack then GOTO step #1

It will be interesting to see what (if anything) comes out of this.

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Restricting Login Usage

Published 2017-12-07 by Kevin Feasel

Kenneth Fisher shows how to prevent people from using those high-power application accounts:

Anyone of these would cause you to fail a security audit. All of them together? Not good.

So how do we fix it? Well, the best possible method is to not give your developers the password. Use config files containing an encrypted copy of the password and you can dramatically limit knowledge of the password. However, that isn’t necessarily a quick or easy solution (modifying the app to use a config file at all for example). So what to do in the meantime?

The simplest thing to do is to create a logon trigger to control where this account can come from. Before we start if you are going to use a logon trigger make sure you know how to log in and disable it if there are any mistakes.

The logon trigger is hardly perfect, but it does help at the margin.

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Protecting RDP With SSH

Published 2017-12-04 by Kevin Feasel

Chrissy LeMaire has a two-parter on enabling SSH tunneling on Windows 10.  First, if you are using the Fall Creators Update:

Gotta say I’m super thankful for Chris K’s blog post “Enabling the hidden OpenSSH server in Windows 10 Fall Creators Update (1709) — and why it’s great!“, otherwise this would have taken me far longer to figure out.

So next, Run PowerShell As Administrator, then generate a key.

cd C:\windows\system32\OpenSSH
ssh-keygen -A

Alternatively, if you are not using the Fall Creators Update:

First, bash for Windows must be setup. This requires Windows 10 or Windows Server 2016.

Note: this was written for Windows 10 pre-1709. Apparently, the new update contains a ton of changes. Developer mode is not required and you install your Linux distro from the Windows Store. Seems that it may even include Open SSH right out the box. I’ll test on Tuesday and let you all know. Till then, here is how to do it if you’ve got Windows 10 without Fall Creators Update (FCU).

Doing this limits the ability of an attacker to snoop on your RDP traffic.

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