Friday, May 5, 2017

The problem with EACMS

The NERC CIP Glossary is foundational to the (let us not forget "mandatory and enforceable") CIP Standards

One of the terms defined there is Electronic Access Control or Monitoring System (EACMS):

"Cyber Assets that perform electronic access control or electronic access monitoring of the Electronic Security Perimeter(s) or BES Cyber Systems. This includes Intermediate Systems."

Disregard the last sentence for a moment. There are a few examples of throw-away statements like this added in NERC CIP for convenience, or exceptions where no one could think of wording that would be universally applicable.

Focus on the meat of the definition: it's an access control and access monitoring system. Outside of NERC CIP Standards, this is generally known as AAA: Authentication, Authorization, and Accounting, which actually captures the steps involved in granting and monitoring access much better than the EACMS definitions. There is also tons of guidance and information on implementing AAA in the broader IT Security realm.

But ignore that for a moment too.

The real problem with NERC CIP Standards and the applicable systems that they list, is that some systems that fall into the EACMS category (plus a number which don't) actually pose a much more significant risk than simple access management. They actually perform configuration management via "service accounts" with elevated privileges.

So for example, an Active Directory system is an EACMS, even though it not only controls access, it also controls configurations. But there is no requirement in NERC CIP to monitor the configuration changes made during a session, only the access to the system. Specifically, the failed and successful login attempts.

SCCM is not specifically an EACMS, even though it has an agent installed on Windows devices, and has an elevated privilege service account with Domain Administrator equivalent permissions. But it doesn't control or monitor access attempts.

There is no requirement to protect these systems any differently than any other user-accessible system, like perhaps a data portal on a web server. There is no requirement to separate user or system access within an ESP based upon roles, or impact levels (another problem with NERC IP is impact level is based upon the facility's physical impact on the Bulk Electric System, not the Cyber System's impact on operations). Once you're in, you're in and there is no requirement and not even any explicit security objective to do more than guard the perimeter. As I've mentioned before, this is the "hard crunchy shell, soft gooey center" model from 20 years ago.

On top of that, there's an exemption to remote access requirements for machine-to-machine communications. A management system located outside the Electronic Security Perimeter isn't even required to have encryption, and has no special requirements above and beyond the simple baseline, change management, and logging requirements applied to any system used to support the BES.


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