NSA Issues Guidance on Securing IT-OT Connectivity

The U.S. National Security Agency (NSA) last week released a cybersecurity advisory focusing on the security of operational technology (OT) systems, particularly in terms of connectivity to IT systems.

The NSA’s advisory, titled “Stop Malicious Cyber Activity Against Connected Operational Technology,” is specifically addressed to the Department of Defense, national security system (NSS) and defense industrial base organizations, but the recommendations can be useful to any industrial company.

The advisory shares recommendations for evaluating risks and improving the securing of connections between IT systems — these can often serve as an entry point into industrial networks — and OT systems.

“Each IT-OT connection increases the potential attack surface,” the NSA said. “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.”

As an example, the agency provided the recent SolarWinds incident, which impacted hundreds of industrial organizations, including in critical infrastructure sectors.

The guidance provided by the NSA focuses on assessing the risk associated with the connectivity between IT and OT systems and steps recommended for improving the security of these connections.

For maximum cyber safety, ideally there should be no connections between enterprise networks and OT networks, but the agency admits that in some cases such connections are necessary. Organizations should review these connections and remove ones that are not truly required, and ensure that the remaining connections are secure, to prevent them from being abused in malicious attacks.

“These mitigations include fully managing all IT-OT connections, limiting access, actively monitoring and logging all access attempts, and cryptographically protecting remote access vectors,” the NSA said.

Over the past few years, the NSA has made public several cybersecurity resources in an effort to help public and private sector companies improve their security posture. The agency released advisories and other materials related to malware, actively exploited vulnerabilities, and the security of widely used internet services.

The advisory released last week is not the first OT-focused resource that has been made public by the NSA. Last year, the NSA and the Cybersecurity and Infrastructure Security Agency (CISA) issued a joint alert urging critical infrastructure operators to take immediate measures to reduce the exposure of OT systems to cyberattacks. 

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