Certificate Authority Security Council Moves Web Security Forward

The CASC was formed two years ago by the major SSL CAs. Here's a look at what the council is doing now and what's next for digital certificate security.

Web security

In February 2013, the largest SSL Certificate Authorities (CAs) in the world came together to create the Certificate Authority Security Council (CASC). Since then, the CASC—whose members include GoDaddy, Comodo, DigiCert, Symantec, GlobalSign, Trustwave, Entrust and Trend Micro—has continued to advance the state of certificate security.

"We started out as an organization that was promoting all things around digital certificates and SSL," Dean Coclin, senior director, business development, Symantec, told eWEEK. "This group is about promoting Internet security and publicly trusted Certificate Authorities through education and advocacy."

Another key goal of the CASC is to help promote the best practices for the proper issuance and use of certificates by CAs, browsers and other interested parties.

The initial effort that the CASC launched with back in 2013 was an initiative to promote the wider deployment of Online Certificate Status Protocol (OCSP) stapling. OCSP is used by Web browsers to check the validity of a Website's Secure Sockets Layer (SSL) certificate. Typically, a browser will need to get a response from an OCSP service running on a CA, though that can potentially affect performance. With OCSP stapling, a Web server can check its own certificate status with the CA, which can then be provided to end-user browsers.

"What we have seen is that OCSP stapling works really well, but getting the message out to server administrators so they enable it has been difficult and challenging," Wayne Thayer, general manager of security products at GoDaddy, told eWEEK. "One of the things we have tried to do is work with server vendors to get OCSP stapling enabled by default."

Thayer has been working with the Apache Software Foundation, which develops the Apache HTTP Web server, to push the OCSP stapling default idea forward. But making changes in the Apache HTTP Web server can be a long process, he added.

"We're making progress, but it will take a while," Thayer said. "I believe that until OCSP stapling is the default setting in Apache, Nginx and other popular Web servers, as it is today in Microsoft's Internet Information Server (IIS), we will have slow uptake."

Looking beyond OCSP stapling, there are multiple ongoing efforts in the CA community to advance the state certificate security. One of them is known as DANE (DNS-based Authentication of Named Entities), which leverages DNSSEC (DNS Security Extensions) as a way to help validate authenticity.

DANE leverages DNS records to give specific instructions to the browser, about which specific CAs or certificates are acceptable for a given Website, Thayer said.

Another emerging effort is known as HTTP Public Key Pinning (HPKP), which is supported today in Google Chrome and Mozilla's Firefox Web browsers. With HPKP, a specific cryptographic public key is associated or "pinned" to a specific server in a bid to limit the risk of potentially fraudulent certificates.

"HPKP is still a draft standard, but the big problem with it is that's it's very easy for an operator to shoot themselves in the foot and brick the site," Thayer said. "By setting a bad pin, the site will fail."

However, HPKP is a viable option for high-risk sites, he said.


Another effort that is currently in development is Certificate Authority Authorization (CAA), which enables a site operator to publish a Domain Name System (DNS) record that the CA checks before issuing a certificate. Some of the work related to CAA is being done in the CA Browser Forum (CAB Forum). Starting on April 15, CAs must publicly state what their policies are on checking CAA records.

"There is progress being made to actually enforce CAA and that helps the CAs, as it helps them to understand when they might be issuing a certificate incorrectly," Thayer said. "It helps the site operators to control how certs are issued for their site."

Certificate Transparency (CT) is another effort that is moving forward to provide additional certificate security. The CT effort is being led by Google and involves the use of CT log servers to which CAs publish certificate information.

"Most, if not all, of the CAs that are part of CASC that issue Extended Validation certificates are now participating in Certificate Transparency by publishing all of their certificates to CT logs," Thayer said.

Internal Names

The CASC has also been advocating in recent months to eliminate what are known as "Internal Names" from SSL certificates. Internal Names are non-unique names that are common on local networks such as "mail" or "exchange.local." CAs have now been mandated to not issue any certificate with an Internal Name that expires after Nov. 1, 2015. Additionally, CAs have been mandated to revoke all existing Internal Name certificates by Oct. 1, 2016.

"Non-unique names and certificates present a real security risk that we're trying to stop in order to improve the overall strength of the SSL ecosystem," Thayer said.

Future Research

The CASC is also now working on some research about how SSL certificate information is viewed by browser users. The research is in progress and will be publicly released in the coming months, Symantec's Coclin said.

"We're interested at the CASC about how people perceive things like EV [Extended Validation] certificates and the associated green bar in the browser and whether it really means something to them," Coclin said. "It's important to figure out if users are respecting warnings or if they are just clicking through them."

Sean Michael Kerner is a senior editor at eWEEK and InternetNews.com. Follow him on Twitter @TechJournalist.

Sean Michael Kerner

Sean Michael Kerner

Sean Michael Kerner is an Internet consultant, strategist, and contributor to several leading IT business web sites.