A lot of organizations are finding out that just turning off SSL is just not an option. This is particularly true of merchants running eCommerce sites predominantly used by mobile customers or customers running older operating systems. To the surprise of a lot of IT people, it turns out that most mobile browsers do not support using TLS. And while most Western PC users have reasonably current browser software, the rest of the world does not and turning off SSL will remove a significant portion of some merchant’s customer base. As a result, for some organizations going “cold turkey” on SSL is just not an option without suffering significant consequences.
But there is a larger problem with SSL lurking inside almost every data center. That is with appliances and data center management software that have SSL baked into them for their Web-based management interfaces. A lot of vendors availed themselves of OpenSSL and other open source SSL solutions to secure communications with their appliances and solutions. To remediate these solutions, an organization might be lucky enough to upgrade the firmware/software. Unfortunately, a lot of organizations are finding that replacement is the only option offered by vendors to address these situations.
The bottom line is that because of these situations, SSL and early TLS will not be addressed by just disabling it and moving on. As the PCI SSC found out when they asked Qualified Security Assessor Companies and Participating Organizations about what it would take to address the SSL/early TLS situation, they were told about these issues and therefore set a deadline of June 30, 2016 to provide time to address these situations.
While organizations have until June 30, 2016 to address SSL and early TLS, that does not mean an organization can just sit by and do nothing until that deadline. Here are some things your organization should be doing to address SSL and early TLS if you are unable to just turn it off.
- Get a copy of NIST Special Publication 800-52 Revision 1 titled ‘Guidelines for the Selection, Configuration and Use of Transport Layer Security (TLS) Implementations’. This publication is the Bible for how to minimize and mitigate the risks of SSL and early TLS.
- Identify all instances of where SSL or TLS are used and versions supported. It is not just those instances that need to be remediated, but all instances. The reason is that TLS v1.3 is in draft specification and its release is likely just around the corner in 2016. That is why a complete inventory is needed so that when TLS v1.3 is available you will know what remaining instances will potentially need to be updated, upgraded or possibly even replaced.
- Implement TLS-FALLBACK-SCSV to minimize the chance of SSL/TLS fallback. This option was developed to address the issue created by POODLE. However, be aware that only certain versions of browsers support this option, so it is not a perfect solution.
- Monitor your external Web sites for SSL and early TLS usage. Track statistics of how many sessions are using SSL or early TLS so that you can determine usage of those protocols and therefore know the actual impact of any decision regarding those protocols. These statistics will also allow you to know when you might be able to pull the plug on SSL and early TLS with minimal impact.
- Modify any external Web sites to present a message to anyone using SSL or early TLS to warn them that you will be no longer supporting SSL/early TLS as of whatever date your organization chooses to drop that support.
- Where possible, configure the Web site to only use SSL or early TLS as the absolute last resort. Unfortunately, a lot of vendors modified their SSL solution to not allow this sort of change so do not be surprised if that does not become an option.
- Develop a migration plan for your remaining instances where SSL or early TLS are used. Contact vendors involved and document what their plans are for dropping SSL and early TLS.
- Be prepared to create compensating controls for SSL and early TLS that you will not be able to remediate by the deadline. Unfortunately, I have a sneaking suspicion that some vendors will miss the June 30, 2016 deadline as will some merchants be unable to turn off SSL by the deadline. As a result, those organizations will have to put compensating controls in place to maintain PCI compliance. These compensating controls will likely be messy and complex as enhanced monitoring will likely be the only controls available.