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On April 29, the National Security Agency (NSA) released the Cybersecurity Advisory, “Stop Malicious Cyber Activity Against Connected Operational Technology” for National Security System (NSS), Department of Defense (DoD), and Defense Industrial Base (DIB) operational technology (OT) owners and operators. The CSA details how to evaluate risks to systems and improve the security of connections between OT and enterprise networks. Information technology (IT) exploitation can serve as a pivot point for OT exploitation, so carefully evaluating the risk of connectivity between IT and OT systems is necessary to ensure unique cybersecurity requirements are met.
Each IT-OT connection increases the potential attack surface. To prevent dangerous results from OT exploitation, OT operators and IT system administrators should ensure only the most imperative IT-OT connections are allowed, and that these are hardened to the greatest extent possible. An example of this type of threat includes recent adversarial exploitation of IT management software and its supply chain in the SolarWinds compromise with publicly documented impacts to OT, including U.S. critical infrastructure.
This guidance provides a pragmatic evaluation methodology to assess how to best improve OT and control system cybersecurity for mission success, to include understanding necessary resources for secure systems:
- First, NSA encourages NSS, DoD, and DIB system owners, operators, and administrators to evaluate the value against risk and costs for enterprise IT to OT connectivity. While the safest OT system is one that is not connected to an IT network, mission critical connectivity may be required at times. Review the connections and disconnect those that are not truly needed to reduce the risk to OT systems and functions.
- Next, NSA recommends taking steps to improve cybersecurity for OT networks when IT-OT connectivity is mission critical, as appropriate to their unique needs. For IT-OT connections deemed necessary, steps should be taken to mitigate risks of IT-OT exploitation pathways. These mitigations include fully managing all IT-OT connections, limiting access, actively monitoring and logging all access attempts, and cryptographically protecting remote access vectors.
Operational technology includes hardware and software that drives the operations of a given infrastructure environment, from an engine control unit in a modern vehicle to nationwide train transportation networks.
Every IT-OT connection creates an additional vector for potential OT exploitation that could impact and compromise mission and/or production. Performing a comprehensive risk analysis for all IT-OT interconnections and only allowing mission critical interconnections when they are properly protected will create an improved cybersecurity posture. By employing an appropriate risk analysis strategy, leadership and system owners and operators can make informed decisions to better manage OT networks while reducing the threats from and impact of exploitation and destructive cyber effects.
Source: NSA
