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Introduction Modeling Distributed Cyber-Physical Systems Formulating Implicit Interactions Identifying Implicit Interactions Concluding Remarks

Identifying Implicit Component Interactions in Distributed Cyber-Physical Systems

50th Hawaii International Conference on System Sciences

Jason Jaskolka1,∗ and John Villasenor1,2

1 Center for International Security and Cooperation

Stanford University, Stanford, CA 94305

2 Department of Electrical Engineering

University of California, Los Angeles, Los Angeles, CA 90095

∗ jaskolka@stanford.edu

January 7, 2017

Jason Jaskolka and John Villasenor HICSS-50 1 / 23

Introduction Modeling Distributed Cyber-Physical Systems Formulating Implicit Interactions Identifying Implicit Interactions Concluding Remarks

Acknowledgement & Disclaimer

Acknowledgement This material is based upon work supported by the U.S. Department of Homeland Security under Grant Award Number, 2015-ST-061-CIRC01. Disclaimer The views and conclusions contained in this document are those of the authors and should not be interpreted as necessarily representing the

• fficial policies, either expressed or implied, of the U.S. Department of

Homeland Security.

Jason Jaskolka and John Villasenor HICSS-50 2 / 23

Introduction Modeling Distributed Cyber-Physical Systems Formulating Implicit Interactions Identifying Implicit Interactions Concluding Remarks

Outline

1

Introduction

2

Modeling Distributed Cyber-Physical Systems

3

Formulating Implicit Interactions

4

Identifying Implicit Interactions

5

Concluding Remarks

Jason Jaskolka and John Villasenor HICSS-50 3 / 23

Introduction Modeling Distributed Cyber-Physical Systems Formulating Implicit Interactions Identifying Implicit Interactions Concluding Remarks Distributed Cyber-Physical Systems Cybersecurity Challenges in Distributed Cyber-Physical Systems Implicit Component Interactions

Distributed Cyber-Physical Systems

Jason Jaskolka and John Villasenor HICSS-50 4 / 23

Introduction Modeling Distributed Cyber-Physical Systems Formulating Implicit Interactions Identifying Implicit Interactions Concluding Remarks Distributed Cyber-Physical Systems Cybersecurity Challenges in Distributed Cyber-Physical Systems Implicit Component Interactions

Cybersecurity Challenges in Cyber-Physical Systems

Ubiquitous and pervasive Large and complex Numerous components or agents Even more interactions, some of which may be:

Unfamiliar, unplanned, or unexpected Not visible or not immediately comprehensible

Software/Hardware from third-party suppliers

Jason Jaskolka and John Villasenor HICSS-50 5 / 23

Introduction Modeling Distributed Cyber-Physical Systems Formulating Implicit Interactions Identifying Implicit Interactions Concluding Remarks Distributed Cyber-Physical Systems Cybersecurity Challenges in Distributed Cyber-Physical Systems Implicit Component Interactions

Cybersecurity Challenges in Cyber-Physical Systems

Ubiquitous and pervasive Large and complex Numerous components or agents Even more interactions, some of which may be:

Unfamiliar, unplanned, or unexpected Not visible or not immediately comprehensible

• Implicit

Interactions Software/Hardware from third-party suppliers

Jason Jaskolka and John Villasenor HICSS-50 5 / 23

Introduction Modeling Distributed Cyber-Physical Systems Formulating Implicit Interactions Identifying Implicit Interactions Concluding Remarks Distributed Cyber-Physical Systems Cybersecurity Challenges in Distributed Cyber-Physical Systems Implicit Component Interactions

Implicit Component Interactions

Can indicate unforeseen flaws allowing for these interactions Constitute linkages of which designers are generally unaware = ⇒ security vulnerability

Hard to avoid simply by intuition Difficult to detect (by nature)

Can be exploited to mount cyber-attacks at a later time

Jason Jaskolka and John Villasenor HICSS-50 6 / 23

Introduction Modeling Distributed Cyber-Physical Systems Formulating Implicit Interactions Identifying Implicit Interactions Concluding Remarks Illustrative Example: Manufacturing Cell Modeling using C2KA

Illustrative Example: Manufacturing Cell

Jason Jaskolka and John Villasenor HICSS-50 7 / 23

Introduction Modeling Distributed Cyber-Physical Systems Formulating Implicit Interactions Identifying Implicit Interactions Concluding Remarks Illustrative Example: Manufacturing Cell Modeling using C2KA

Illustrative Example: Manufacturing Cell

Jason Jaskolka and John Villasenor HICSS-50 7 / 23

Introduction Modeling Distributed Cyber-Physical Systems Formulating Implicit Interactions Identifying Implicit Interactions Concluding Remarks Illustrative Example: Manufacturing Cell Modeling using C2KA

Illustrative Example: Manufacturing Cell

Storage Agent Handling Agent Processing Agent Control/Coordination Agent

Jason Jaskolka and John Villasenor HICSS-50 7 / 23

Introduction Modeling Distributed Cyber-Physical Systems Formulating Implicit Interactions Identifying Implicit Interactions Concluding Remarks Illustrative Example: Manufacturing Cell Modeling using C2KA

Illustrative Example: Manufacturing Cell

Message Passing

Control Agent (C) Handling Agent (H) Processing Agent (P) Storage Agent (S) (1) start (2) load (3) loaded (6) unloaded (4) prepare (5) unload (7) setup (10) done (8) ready (9) process (9) process (10) processed

Jason Jaskolka and John Villasenor HICSS-50 8 / 23

Introduction Modeling Distributed Cyber-Physical Systems Formulating Implicit Interactions Identifying Implicit Interactions Concluding Remarks Illustrative Example: Manufacturing Cell Modeling using C2KA

An Algebraic Modeling Framework

Communicating Concurrent Kleene Algebra (C2KA)

Formalism for modeling distributed multi-agent systems Extension of Concurrent Kleene Algebra (CKA) Captures communication and concurrency of agents at an abstract algebraic level Expresses influence of stimuli on agent behavior in open systems as well as communication through shared environments

Other existing formalisms do not directly deal with describing how agent behaviors are influenced by stimuli

Primarily concerned with closed systems

Jason Jaskolka and John Villasenor HICSS-50 9 / 23

Introduction Modeling Distributed Cyber-Physical Systems Formulating Implicit Interactions Identifying Implicit Interactions Concluding Remarks Illustrative Example: Manufacturing Cell Modeling using C2KA

Communicating Concurrent Kleene Algebra (C2KA)

Definition (C2KA)

A Communicating Concurrent Kleene Algebra (C2KA) is a system

• S, K
• , where

S =

• S, ⊕, ⊙, d, n
• is a stimulus structure

K =

• K, +, ∗, ; , *

, ; , 0, 1

• is a CKA
• SK, +
• is a unitary and zero-preserving left S-semimodule with next behavior

mapping ◦ : S × K → K

• SK, ⊕
• is a unitary and zero-preserving right K-semimodule with next stimulus

mapping λ : S × K → S and where the following axioms are satisfied for all a, b, c ∈ K and s, t ∈ S:

1

s ◦ (a ; b) = (s ◦ a) ; λ(s, a) ◦ b

• 2

a ≤K c ∨ b = 1 ∨ (s ◦ a) ; λ(s, c) ◦ b

• = 0

3

λ(s ⊙ t, a) = λ

• s, (t ◦ a)
• ⊙ λ(t, a)

4

s = d ∨ s ◦ 1 = 1

5

a = 0 ∨ λ(n, a) = n

Jason Jaskolka and John Villasenor HICSS-50 10 / 23

Introduction Modeling Distributed Cyber-Physical Systems Formulating Implicit Interactions Identifying Implicit Interactions Concluding Remarks Illustrative Example: Manufacturing Cell Modeling using C2KA

Agent Specifications

Illustrative Example: Manufacturing Cell

Table: Stimulus-response specification of the Control Agent C

• start

load loaded prepare done unload unloaded setup ready process processed idle idle idle prep idle idle idle idle idle idle idle idle prep prep prep prep prep prep prep init prep prep prep prep init init init init init init init init init init proc init proc proc proc proc proc proc proc proc proc proc proc idle λ start load loaded prepare done unload unloaded setup ready process processed idle load n prepare n n n n n n n n prep n n n n n n setup n n n n init n n n n n n n n n done n proc n n n n n n n n n n end

Control Agent C →

• idle + prep + init + proc
• Storage Agent S

→

• empty + full
• Handling Agent H

→

• wait + move
• Processing Agent P

→

• stby + set + work
• Figure: Abstract behavior specification of the manufacturing cell agents

Jason Jaskolka and John Villasenor HICSS-50 11 / 23

Introduction Modeling Distributed Cyber-Physical Systems Formulating Implicit Interactions Identifying Implicit Interactions Concluding Remarks Intended Systems Interactions Formulation of Implicit Interaction Existence

Intended System Interactions

Control Agent (C) Handling Agent (H) Processing Agent (P) Storage Agent (S) (1) start (2) load (3) loaded (6) unloaded (4) prepare (5) unload (7) setup (10) done (8) ready (9) process (9) process (10) processed

Pintended denotes the set of intended system interactions

Jason Jaskolka and John Villasenor HICSS-50 12 / 23

Introduction Modeling Distributed Cyber-Physical Systems Formulating Implicit Interactions Identifying Implicit Interactions Concluding Remarks Intended Systems Interactions Formulation of Implicit Interaction Existence

Illustrative Example: Manufacturing Cell

Intended System Interactions

C S C H S C P H P C P C Pintended =

• C → S → C → H → S → C → P → H → P → C,

C → S → C → H → S → C → P → H → C → P

• Jason Jaskolka and John Villasenor

HICSS-50 13 / 23

Introduction Modeling Distributed Cyber-Physical Systems Formulating Implicit Interactions Identifying Implicit Interactions Concluding Remarks Intended Systems Interactions Formulation of Implicit Interaction Existence

Illustrative Example: Manufacturing Cell

Intended System Interactions

C S C H S C P H P C P C Pintended =

• C → S → C → H → S → C → P → H → P → C,

C → S → C → H → S → C → P → H → C → P

• Jason Jaskolka and John Villasenor

HICSS-50 13 / 23

Introduction Modeling Distributed Cyber-Physical Systems Formulating Implicit Interactions Identifying Implicit Interactions Concluding Remarks Intended Systems Interactions Formulation of Implicit Interaction Existence

Illustrative Example: Manufacturing Cell

Intended System Interactions

C S C H S C P H P C P C Pintended =

• C → S → C → H → S → C → P → H → P → C,

C → S → C → H → S → C → P → H → C → P

• Jason Jaskolka and John Villasenor

HICSS-50 13 / 23

Introduction Modeling Distributed Cyber-Physical Systems Formulating Implicit Interactions Identifying Implicit Interactions Concluding Remarks Intended Systems Interactions Formulation of Implicit Interaction Existence

Formulating Existence of Implicit Interactions

Definition (Existence of Implicit Interactions) An implicit interaction (via stimuli) exists in a system formed by a set A

• f agents, if and only if for any two agents A, B ∈ A with A = B:

∃

• p | p =

⇒ (A →+

S B) :

∀(q | q ∈ Pintended : ¬SubPath(p, q) )

• where SubPath(p, q) is a predicate indicating that p is a subpath of q.

Jason Jaskolka and John Villasenor HICSS-50 14 / 23

Introduction Modeling Distributed Cyber-Physical Systems Formulating Implicit Interactions Identifying Implicit Interactions Concluding Remarks Identification of Implicit Interactions Experimental Results

Identifying Implicit Interactions

1

Determine the potential communication paths that exist from the system specification

Example: Consider the manufacturing cell:

$ pfc system agentP agentS P ->+ S: True P

• >

C

• >

H

• >

S P

• >

C

• >

S P

• >

H

• >

C

• >

S P

• >

H

• >

S $ pfc system agentH agentC H ->+ C: True H

• >

C H

• >

P

• >

C H

• >

S

• >

C

Control Agent (C) Handling Agent (H) Processing Agent (P) Storage Agent (S)

Jason Jaskolka and John Villasenor HICSS-50 15 / 23

Introduction Modeling Distributed Cyber-Physical Systems Formulating Implicit Interactions Identifying Implicit Interactions Concluding Remarks Identification of Implicit Interactions Experimental Results

Identifying Implicit Interactions

2

Determine if a potential communication path is an implicit interaction

Example: Consider the following potential communication paths: H → S → C and P → C → S

P → C → S Pintended =

• C → S → C → H → S → C → P → H → P → C,

C → S → C → H → S → C → P → H → C → P

• Jason Jaskolka and John Villasenor

HICSS-50 16 / 23

Introduction Modeling Distributed Cyber-Physical Systems Formulating Implicit Interactions Identifying Implicit Interactions Concluding Remarks Identification of Implicit Interactions Experimental Results

Identifying Implicit Interactions

Control Agent (C) Handling Agent (H) Processing Agent (P) Storage Agent (S)

Jason Jaskolka and John Villasenor HICSS-50 17 / 23

Introduction Modeling Distributed Cyber-Physical Systems Formulating Implicit Interactions Identifying Implicit Interactions Concluding Remarks Identification of Implicit Interactions Experimental Results

Identifying Implicit Interactions

Control Agent (C) Handling Agent (H) Processing Agent (P) Storage Agent (S)

C S C H S C P H P C P C

Jason Jaskolka and John Villasenor HICSS-50 17 / 23

Introduction Modeling Distributed Cyber-Physical Systems Formulating Implicit Interactions Identifying Implicit Interactions Concluding Remarks Identification of Implicit Interactions Experimental Results

Experimental Results

For the manufacturing cell system:

11 of the 30 total interactions are implicit interactions

Result of the potential for out-of-sequence stimuli from system agents Demonstrates hidden complexity and coupling among agents

Potential for unexpected system behaviors

Jason Jaskolka and John Villasenor HICSS-50 18 / 23

Introduction Modeling Distributed Cyber-Physical Systems Formulating Implicit Interactions Identifying Implicit Interactions Concluding Remarks Impact of this Research Future Research Directions Concluding Remarks Questions

Impact of this Work

Enhances the understanding of the hidden complexity and coupling in distributed cyber-physical systems Formal foundation upon which mitigation approaches can be developed Basis for developing guidelines for designing and implementing cyber-physical systems that are resilient to cyber-threats

Jason Jaskolka and John Villasenor HICSS-50 19 / 23

Introduction Modeling Distributed Cyber-Physical Systems Formulating Implicit Interactions Identifying Implicit Interactions Concluding Remarks Impact of this Research Future Research Directions Concluding Remarks Questions

Impact of this Work

Enhances the understanding of the hidden complexity and coupling in distributed cyber-physical systems Formal foundation upon which mitigation approaches can be developed Basis for developing guidelines for designing and implementing cyber-physical systems that are resilient to cyber-threats There is still much more to be done!

Jason Jaskolka and John Villasenor HICSS-50 19 / 23

Introduction Modeling Distributed Cyber-Physical Systems Formulating Implicit Interactions Identifying Implicit Interactions Concluding Remarks Impact of this Research Future Research Directions Concluding Remarks Questions

Where Do We Go From Here?

Extension with potential for communication via shared environments Classification and measurement of severity

Measure the exploitability of identified implicit interactions Study impact of implicit interactions through simulation

Articulate mitigation approaches Study the applicability on real systems

Jason Jaskolka and John Villasenor HICSS-50 20 / 23

Introduction Modeling Distributed Cyber-Physical Systems Formulating Implicit Interactions Identifying Implicit Interactions Concluding Remarks Impact of this Research Future Research Directions Concluding Remarks Questions

Concluding Remarks

Implicit component interactions can pose a serious cyber-threat to cyber-physical systems Elimination of implicit interactions in an ongoing and ambitious undertaking Focus on evolving and enhancing the understanding of our modern systems and networks

Jason Jaskolka and John Villasenor HICSS-50 21 / 23

Introduction Modeling Distributed Cyber-Physical Systems Formulating Implicit Interactions Identifying Implicit Interactions Concluding Remarks Impact of this Research Future Research Directions Concluding Remarks Questions

Questions Questions?

Jason Jaskolka and John Villasenor HICSS-50 22 / 23

Introduction Modeling Distributed Cyber-Physical Systems Formulating Implicit Interactions Identifying Implicit Interactions Concluding Remarks Impact of this Research Future Research Directions Concluding Remarks Questions

Thank You Thank You!

Jason Jaskolka and John Villasenor HICSS-50 23 / 23