NGNIX, SSL Certificates and PC-DSSI 3.1

Question

We are going to have to pass a PCI 3.1 audit for the web application we're currently developing. It's on Amazon EC2 running NGINX under Debian.

We're in contact with Symantec for certificates and we're particularly interested in the Secure Site Pro with EV one and the Wildcard one (we would have one server with dynamic sub-domain names and that's why we're thinking about the wildcard one)

I just wanted to make sure I'm not going to spend thousands of dollars and find out these aren't adequate for PCI 3.1 or that someone the combination of NGINX and Debian is not going to be working for those types of certs.

Does anyone have experience with trying to be PCI-DSS 3.1 compliant that can give some advice as to which SSL certificates we should be getting?

Answer 1

Caveat: I never had to go through PCI certification. This is based on my research on this topic for your question.

It looks like the primary difference between PCI3.0 and PCI3.1 is that 3.1 requires TLS1.1 or higher. Can't use SSL3 or TLS1.0. See http://www.infosecurity-magazine.com/news/pci-dss-31-forces-move-from-ssl-to/ Although, in some places they even mention that TLS1.1 is not allowed. However, having only TLS1.2 you'd be cutting off a potentially very large number of your visitors such as Android below 4.4 and all IE below 11. If that's acceptable to your business, go for it.

Furthermore, it seems like EV certificates are not explicitly required. They are beneficial for site recognition to help deter phishing, but it's not a strict requirement for PCI.

I also see nothing that would forbid wildcard certs.

You can get any wildcard cert as long as its chain of trust is part of your visitor's browser. It doesn't have to be an EV cert and it doesn't have to be from Symantec.

An important part of your setup is to make sure that your Nginx or other SSL-terminating software/hardware uses correct encryption settings. Mozilla created a nice page that allows you to pick your components and their versions and it'll generate "best practices" config for you. See https://mozilla.github.io/server-side-tls/ssl-config-generator/ and https://wiki.mozilla.org/Security/Server_Side_TLS

Answer 2

TL;DR: PCI-DSS 3.1 is effective immediately, but the requirement to disable TLS 1.0 and SSL 3 takes effect after 30 June 2016.

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In most cases you should have already disabled SSL 3 months ago, or more, for the POODLE vulnerability. So that isn't a concern.

The interesting part of this requirement is not being able to use TLS 1.0.

The official word is:

SSL and early TLS are not considered strong cryptography and cannot be used as a security control after 30th June, 2016. Prior to this date, existing implementations that use SSL and/or early TLS must have a formal Risk Mitigation and Migration Plan in place. Effective immediately, new implementations must not use SSL or early TLS. POS POI terminals (and the SSL/TLS termination points to which they connect) that can be verified as not being susceptible to any known exploits for SSL and early TLS, may continue using these as a security control after 30th June, 2016.

-- Migrating from SSL and Early TLS, PCI-DSS Information Supplement

Where "early TLS" is defined as TLS 1.0. Only TLS 1.1 and 1.2 will be permitted, and 1.2 is strongly recommended.

While you will still be allowed to use TLS 1.0 and SSL 3 for point of sale devices and their backends, provided you can prove you've mitigated every possible problem, you should strongly consider updating these as well.

As an aside, this is yet another nail in Windows XP's coffin...