I’ve already
mentioned
that the highlight of RF’s CIP workshop in April was the joint presentation by
Felek Abbas of NERC and Lew Folkerth of RF, which addressed various current
topics in CIP. Felek gave a very good presentation on CIP-003-7, which includes
the revised requirement for electronic access control at Low impact assets that
have external routable connectivity (CIP-003-7 was approved by the NERC ballot
body and Board of Trustees, and is now awaiting FERC approval).
Felek spent
a lot of time on the Reference Models that provide examples of different ways
to comply with this new requirement; these are found in the Guidance and
Technical Basis for CIP-003-7. When he discussed Reference Model 5 (found on
page 39), he pointed out - and I agree with him - that this model addresses
FERC’s concern that led them to order NERC to clarify the meaning of the word
“Direct” in the LERC definition in CIP v6 (as you probably know, the current CIP
Modifications drafting team decided to eliminate the defined terms LERC and
LEAP altogether, instead incorporating them into the requirement itself. For a
description of what they did, read this
post, although if that isn’t punishment enough, you could read this
one). I’d like to clarify why Reference Model 5 does actually address what FERC
asked for, although this isn’t the point of this post. You can skip the next
two paragraphs if this historical item isn’t of interest to you.
Reference
Model 5 shows a routable communication stream entering a Low asset, but then
being converted to a non-routable protocol for connection to a Low impact BES
Cyber System. In 2014 and 2015, as NERC entities realized the clock was ticking
on coming into compliance with CIP v5, there was a lot of discussion
about whether or not just converting a routable to a serial connection (e.g.
with a protocol converter) was enough to “break” External Routable Connectivity
for Medium BCS. The regions and NERC made it fairly clear that merely
converting the protocol wouldn’t break ERC, but it was also clear that the ERC
definition itself didn’t provide an answer to this question.
Of course,
at the time there was no requirement regarding electronic access control at Low
assets (and also no LERC), since the CIP v6 drafting team was still working on
this. CIP v6 was approved in January 2016, and by then FERC was worried enough
about this issue that they explicitly included it in their order
approving v6; that is, they required NERC to clarify the meaning of “Direct” in
the LERC definition. Reference Model 5 shows (using the green dotted line) that
the protocol conversion by itself doesn’t change the fact that there is
external routable connectivity to a Low BCS. However, the fact that the
“non-BES Cyber Asset” in Reference Model 5 also performs electronic access
control is deemed sufficient
mitigation of the risk caused by the presence of external routable connectivity
to one or more Low BCS – which is the objective of the revised requirement. So
Reference Model 5 shows one way to comply with the revised requirement in CIP
v7 (indeed, the other Reference Models all show alternative ways to comply).
At this
point, somebody in the audience raised the question of “jungle muxes”. These
are devices – often found in substations – that accept a routable external
connection, but then convert that into a number of serial connections to a set
of serial devices (often relays). The question was whether, since the mux does
communicate routably, it has to have an Electronic Security Perimeter around
it.
Felek
answered this question by going back to a Lesson
Learned that dealt with communications between two Medium and/or High
assets, at least one of which doesn’t have an ESP (i.e. it doesn’t have any
internal routable network). The Lesson Learned was occasioned by the fact that
Section 4.2.3.2 of all the CIP v5 and v6 standards (it’s also found in v7, at
least in CIP-003-7) says that cyber assets involved in communications between
“discrete” ESPs are exempt from CIP; at the same time, under v5 and v6 (unlike
in v3) there can be assets subject to CIP that don’t contain any routably
connected devices. The Lesson Learned addressed the question whether the cyber
assets that are associated with the communications network between two Medium and/or
High assets, one or both of which doesn’t have an ESP, are also exempt from
CIP, and if so where the “inter-asset” communications stream begins in an asset
without an ESP.
That Lesson
Learned introduced the idea of the Demarcation Point (which is an old idea from
the days when dinosaurs roamed the Earth and data communications was mostly
over phone lines), as the device where the external communications carrier
“takes over” from the building’s internal communications network. The LL said
that an entity complying for an asset without an ESP should designate the
device that is best described as the demarc point. All cyber assets that are
“inside” of this device are potentially in scope for CIP; all cyber assets that
are “outside” of this device are not.
Felek said
that, even though the jungle mux does have a routable connection, the fact that
this connection is used purely for external communications – and that there are
no other devices at the Low asset that communicate routably – means the mux
itself can be considered the demarcation point. Thus, it doesn’t need an ESP.[i]
I thought
Felek’s answer was very good, but I was even more impressed by the fact that he
was willing to state it in a meeting with 200 or so representatives from NERC
entities in attendance. There are some who might consider what he said to be an
“interpretation” of the wording of a standard, rather than simply
implementation guidance. NERC and regional employees are permitted to provide
the latter but not the former; in practice, this has meant that a lot of
questions about CIP v5 and v6 have only been answered in private conversations
(primarily in the private Small Group Advisory Sessions that were conducted in
2015 and 2016) or not at all. Felek wasn’t afraid to publicly state his opinion
on a disputed issue like this; I wish it would happen more often.
The views and opinions expressed here are my own and don’t
necessarily represent the views or opinions of Deloitte.
[i] Of course, this isn’t to say that the serial devices
that connect to the mux don’t have external routable connectivity. Whether they
do or don’t depends on what happens at the jungle mux. The definition of ERC is
“The ability to access a BES Cyber System from a Cyber Asset that is outside of
its associated Electronic Security Perimeter via a bi-directional routable
protocol connection.” If all the jungle mux does is convert the routable communications
stream to serial and send it to the proper device, then there is ERC. If the
mux performs some sort of authentication, then this probably removes that
ability, and there is no ERC.
However, I’ll admit this is still an ambiguous area,
and that points to an interesting irony. That is because FERC’s qualms about
the ERC definition (discussed above in this post) led to a change; but the
change was in the LERC definition, not ERC. When FERC ordered NERC to clarify
the meaning of “Direct” in the LERC definition – in the order approving CIP v6
in Order
822 in January 2016 – they weren’t reacting to problems with LERC since it
wasn’t in effect yet. They were really responding to the discussions about ERC in
2014 and 2015 that I described above (I linked above to just one of the posts I
wrote on this issue. Others include this one, this
one, this
one (in the order I wrote them). I believe FERC was especially concerned about
the idea that mere protocol conversion “breaks” ERC.
If you want to plow through these three posts, you will
see that, by the third one, I had concluded (in conjunction with Morgan King, a
WECC auditor who has weighed in a lot on technical issues like this) that mere
protocol conversion didn’t break ERC, but requiring re-authentication would. I
thought when I wrote the third post that this was the last word on the subject.
However, in this
post, which was written a few days after the third one, I reported that another
auditor said this wasn’t enough to break ERC – that there had to also be “reformulation
of the user’s commands and the acting as a proxy for the user”.
At this point, I threw up my hands and decided ERC was
a black hole – I could write 100 posts and never get to the bottom of the
problem, which was that the definition needed to be rewritten. I believe this
is one of the tasks on the CIP Modifications SDT’s agenda, and I hope they do
this. I think they should build on the very good work they did with the LERC
issue last year, and base their new definition of ERC on use cases similar to
the ones they developed for CIP-003-7 (although some of those cases won’t apply
because the new Section 3.1 “defines” what used to be LERC in terms of the
asset’s boundary, in order to avoid requiring a list of BCS at Lows). I think
any attempt to write a dictionary-style definition will fail. They just need to
say “In these cases, there is ERC. In these cases, there isn’t ERC.”
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