TLS 1.0 and TLS 1.1 removal for Stack Exchange services

Question

Update (2020-02-13): This change was completed last night on the Fastly side. Most of our endpoints now have TLS 1.0 and 1.1 disabled. We’ll be addressing our direct load balancers next.

Update (2020-02-25): This change was applied to our load balancers directly - TLS 1.0 and 1.1 are now disabled for all Stack Exchange properties.

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As part of our regular efforts to increase security and keep up with the times, we will be disabling TLS 1.0 and 1.1 for Stack Exchange services on February 12th, 2020. TLS 1.2 and above will continue to work. Note: this will not immediately affect all services. Some of our services are handled via Fastly, and some at our load balancers directly - this change will not affect both segments at once. Things like Q&A, Talent, etc. flow through Fastly and will be the first affected. Things that are direct, like Chat and our API, will not be affected immediately.

Why?

Most browsers and operating systems moved to TLS 1.2 quite a while ago now (for example, we don't support Windows XP...and neither does Microsoft). We held out for as many clients as possible to move over, but now it's time to make the change. If you're curious what the vulnerabilities are in TLS 1.0 and 1.1, there's a good writeup here. We've been monitoring traffic levels over the past few months and we are now at HTTPS stats of:

• TLS 1.0: 0.6%
• TLS 1.1: 0.0%
• TLS 1.2: 99.4%

Additionally, it looks like the vast majority of the TLS 1.0 traffic is bots (and/or sends no user agent at all) - our estimate is that 'not a robot' requests account for less than a third of that 0.6%.

As an example of the industry moving on here, our current SSL Labs rating is a B. This is purely because of remaining TLS < 1.2 support that we plan to remove here. (Update: we are now at an A+ rating.)

If anyone has questions, please feel free to comment or answer below and we'll try and keep up.

Answer 1

Removing support for outdated security technologies is surely a good move. But

I see your statistics includes only TLS 1.2, so do you have any plan for TLS 1.3? It's the new standard in 2018 and is supported by all major browsers (excl. IE) and a lot of cloud services (Cloudflare, AWS ELB etc.). I really think that should be added as well.

Answer 2

EDIT: now fixed

When you write "we will be deprecating TLS 1.0 and 1.1", do you mean that they will no longer work after next week?

It seems so from your next sentence, but this is confusing to me, because in my experience that is not what "deprecating" means in the programming world:

Software deprecation

While a deprecated software feature remains in the software, its use may raise warning messages recommending alternative practices; deprecated status may also indicate the feature will be removed in the future. Features are deprecated rather than immediately removed, to provide backward compatibility, and to give programmers time to bring affected code into compliance with the new standard.

from https://en.wikipedia.org/wiki/Deprecation, and, from https://en.wiktionary.org/wiki/deprecate (emphasis mine):

2. (transitive, chiefly computing) To declare something obsolescent; to recommend against a function, technique, command, etc. that still works but has been replaced.

Answer 3

Running the Immuniweb.com Security Test it complains (abbreviated version):

The problem is TLSv1.1 and TLSv1.0 configured with TLS_RSA_WITH_3DES_EDE_CBC_SHA enabled, that is non-compliant with PCI DSS requirements. In particular, the test complains of supporting TLSv1.0 and lack of support for TLSv1.3. in addition it says: "The HTTP version of the website does not redirect to the HTTPS version. We advise to enable redirection.".

You probably know this but the latest guidelines are: SP 800-52 Rev. 2 "Guidelines for the Selection, Configuration, and Use of Transport Layer Security (TLS) Implementations".

There is also hardware available, such as Symantec's SSL Visibility Appliance, which can permit security tools to operate despite end-to-end encryption; but it's expensive. Despite the expense traffic inspection is necessary unless you simply want to hope that nothing can go wrong. There are also Data Loss Prevention Appliances which can detect theft of personal information, password files, and other sensitive data; and block it before it goes over the wire.

Your move to TLS 1.2 and up is a welcome one, we wouldn't want you to go down for a few days or suffer the annoyance (warning?) of last year's hack again. Thanks for keeping on the leading edge.

Answer 4

Not everyone on here is a programmer or a tech expert, and in what I've seen online about this it's still technological mumbo-jumbo to me. Can someone please give a simple explanation of what exactly is this change and why is it important?

Answer 5

This is a pretty bad idea, following a trend that's based on common misunderstandings of how protocols work, and undermining the value of robustness and interoperability (also known as Postel's law).

• Browser vendors have announced that they'll be deprecating support for TLSv1.0 and TLSv1.1 in 2020. It is often cited that TLSv1.0 is removed in order to avoid downgrade attacks. But if supported browsers don't support anything below TLSv1.2, then there's nothing for them to downgrade to, so, there doesn't seem to be a good reason to remove support on the websites as well.

• This change means that it will no longer be possible to view your properties from older iPad, iPhone, Android and webOS devices, for little good reason. Keep in mind, these are devices that have gigabytes of storage and hundreds of megabytes of memory each, these are not some outdated devices that don't have the processing power to do common tasks, these are very powerful devices that simply have been abandoned by their vendors. This will result in an effective link rot on a rather large scale (search results from Google will no longer work), and will widen the digital gap between people who don't have the resources to buy the latest tablets, phones and other gadgets. You're effectively doing the brokering for planned obsolescence on behalf of Apple and other vendors, contributing to the global warming by deprecating very powerful devices, each with gigabytes of storage and megabytes of RAM, which are still perfectly capable of performing complex computing tasks.

• SSL Labs rating is a B. Only a third of 0.6% of visitors require TLSv1.0. You're basically telling us that you'd rather have a better rating on a meaningless scale by completely denying access to your website only for a few million actual, real users. Is this for real? Is this what our industry has become?

Please consider doing the following instead:

• Bring back full HTTP access. With an HSTS policy in place, none of the supported browsers will ever notice that HTTP support is even available. With HSTS (which is already in place on Stack Overflow), all http:// links are treated as https://, so, there's no effective difference for any supported browser, but the older devices that may not have recent https support could still view the site. (For new visitors, all you have to do is have an invisible pixel to your HTTPS site from the HTTP one, which will automatically install HSTS policy, and no further requests will be made over HTTP; this is trivial to accomplish, and should seamlessly support both legacy and modern browsers.)

• Do not disable TLSv1.0 (and noone cares for TLSv1.1 either way, as there's hardly anything that supports TLSv1.1 without also supporting TLSv1.2). Even if HTTP access is available, browsers that don't support TLSv1.2 would not be able to follow the existing https:// links due to lack of TLSv1.2 support, resulting in link rot. (If there's a worry about certificate compromise with serving TLSv1.0, it's rather trivial to divert TLSv1.0 and TLSv1.2 traffic to distinct servers that each have distinct certificates, serving distinct content, without TLSv1.2-only clients being affected in any negative way; if TLSv1.0 is somehow deemed to be so insecure as to being worse than straight HTTP, then it's also an option to redirect back from HTTPS to HTTP for such old TLSv1.0-only clients in order to not contribute to link rot.)