Microsoft have announced this week that future versions of Windows will disable TLS (Transport Layer Security) 1.0 and 1.1 by default. These ageing cryptographic protocols are designed to secure traffic over a network. The move is a bid to improve the security posture in Windows by ensuring that only newer versions of TLS are used between client and server applications.
TLS 1.0 and 1.1 were standardised in 1999(!) and 2006 respectively. They were both deprecated in 2021 via RFC 8996. Although Microsoft claims that no known unpatched exploits exist in the Schannel implementation newer versions of TLS offer much better security. With older versions of TLS a number of bodies have mandated that these older versions should be avoided. For example as the Payment Card Industry (PCI) have deprecated their use since 2018. There are a number of security flaws with both TLS 1.0 and 1.1 which means that we can no longer rely on them for securing traffic.
In addition all major browsers have dropped support for anything prior to TLS 1.2 since 2020. As with all things in computing security it’s best to be ahead rather than behind. There shouldn’t be any browsers and OSes out there that are still supported and can’t use at least TLS 1.2. I fully recommend keeping ahead with developments and plan accordingly to drop anything prior to TLS 1.2.
SQL Server and Applications Impacted
Although Microsoft believe that usage of deprecated versions of TLS are low via their telemetry it would be wrong to simply assume that you can turn off TLS 1.0/1.1 and job done.
If you aren’t sure about how this will impact your business it’s time to start with a review of your applications and how they will be affected. Soon there will be Windows desktops out there that definitely don’t support older versions of TLS out of the box. Whilst Microsoft have stated that you can re-enable TLS 1.0 and 1.1 via the Schannel registry keys in the meantime you absolutely shouldn’t bother with doing so. There’s a reason things move on. Microsoft will at some point do the right thing and completely remove deprecated versions of TLS from the operating system. Putting off the problem won’t solve anything long-term.
Possibly the most direct way this affects SQL Server based applications is indeed the front-end. Many applications now work via a web UI rather than a Windows application. This is perhaps where your investigations should start.
For internet facing applications you could run a test via Qualys which will produce a useful report on how your server is configured. Scroll down and you’ll see the projected impact regarding client browsers and OSes with what versions of TLS they might use.
If your applications are internal only it’s not wise to assume that your wires and airwaves are safe even if you own them. for these you can check the Schannel registry keys at the following location:
You can check individual protocols at this location to see if they are enabled or disabled.
Getting down to the SQL Server level things get more interesting. Support for TLS 1.2+ exists as of SQL Server 2016 so these versions are good to go out of the box.
For SQL Server 2014 if you have these configured with an encrypted connection this version needs a cumulative update applying before it will support TLS. By now you really, really should have applied an update beyond the version this was introduced anyway. for any new deployments of SQL Server 2014 instances you might have to do remember to apply CUs after you’ve done the install.
For SQL Server 2008, 2008 R2 and 2012 things are arguably beyond the point with those releases as they are no longer supported. You can get yourself a hotfix to apply to those too but unless this is for an application that’s segregated away in some corner of the network for legacy purposes you’ve either got bigger things to worry about or another good reason to upgrade if this is a production system for some reason.
Potentially you’ll need to update the client driver if they use the SQL Server Native driver. Check with the application vendor for the system requirements for this.