DHS Guidance on Cyber-Hardening of Positioning, Navigation, and Timing Systems
Published: June 16, 2022
The Homeland Security Department’s tech innovation agency is seeking to aid producers of PNT-enabled technologies in building in cyber resilience.
The Department of Homeland Security (DHS) Science and Technology Directorate (S&T) recently published a Resilient Positioning, Navigation, and Timing (PNT) Reference Architecture to provide “a concrete vision for a holistic approach” to building Next Generation Resilient PNT systems which incorporate modern cybersecurity to protect against current and future threats.
PNT services and systems leverage the Global Positioning System (GPS) and other Global Navigation Satellite Systems (GNSS) to provide applications across many infrastructure sectors, including communications, transportation, agriculture, financial services, the electric power grid, and emergency services. As these capabilities have grown, the potential impacts of their disruption on individuals, businesses, first responders and the military has also grown.
Next Generation Resilient PNT Systems, Built Upon Zero Trust Architectures
One assumption underpinning S&T’s approach is that most current PNT user equipment (UE) was not designed with resilience as a priority and therefore may be vulnerable to either unintentional disruptions or targeted attacks.
The Reference Architecture provides a vision for a holistic approach to Next Generation Resilient PNT systems. Careful application of these concepts and techniques can produce PNT equipment that is highly resilient to current and future PNT threats and strengthen critical infrastructure.
Recognizing the reality that perfect security is a misnomer and that there will likely always be unintentional vulnerabilities to all UE, the core principle of their Reference Architecture (RA) is managed trust derived from Zero Trust Architectures (ZTA), which limit the impact of attacks when systems are penetrated. The RA seeks to show how to adapt cyber resiliency concepts, ZTA, and other cybersecurity concepts to the unique characteristics of PNT UE systems. The RA is then designed around seven PNT resilience concepts: Obfuscate, Limit, Verify, Isolate, Mitigate, Diversify, and Recover.
S&T provides samples of resilient PNT UE system architectures that show how system designers can layer various resilience techniques to progress from lower to higher levels of resilience. The RA further explores how to design resilient PNT UE systems given the challenges confronting PNT UE component subsystems, as well as considering PNT resilience in the broader context of PNT assurance and PNT situational awareness (SA).
The RA builds upon S&T’s Resilient Positioning, Navigation, and Timing (PNT) Conformance Framework v2.0, updated in May. The conformance framework has four cumulative levels of resilience – Levels 1-4 – based around the core functions of Prevent, Respond, and Recovery. Levels 1 and 2 address critical legacy issues and Levels 3 and 4 focus on future PNT equipment, so the higher levels produce greater resilience. The architecture implementation examples provided within the reference architecture align with the conformance framework.
The latest reference architecture and conformance framework are relevant to equipment vendors and those interested in the design of resilient PNT systems, including software producers – all of which may be procured by federal agencies. As scrutiny of commercial products and services in the federal supply chain continues to increase, including policies around software supply chain security, suppliers and integrators will be required to show that their products and processes rise to the occasion.
The Office of Management and Budget (OMB) has put federal departments and agencies on a path to ZTA by 2024. As agencies move to fully implement ZT principles and architectures they will be looking for the devices, software products and commercial services they procure to both integrate seamlessly into their environments and to support their overall cybersecurity posture, not degrade it.