The Cybersecurity and Infrastructure Security Agency (CISA), in collaboration with international partners, has released a pivotal document titled Foundations for OT Cybersecurity: Asset Inventory Guidance for Owners and Operators. This guidance aims to bolster cybersecurity defenses across critical infrastructure sectors by emphasizing the importance of maintaining accurate operational technology (OT) asset inventories.
The Rising Threat to Operational Technology
In recent years, malicious cyber actors have increasingly targeted industrial control systems (ICS), supervisory control and data acquisition (SCADA) systems, and programmable logic controllers (PLCs) within sectors such as energy, water, and manufacturing. These attacks often exploit vulnerabilities in legacy systems, weak authentication mechanisms, insufficient network segmentation, insecure OT protocols like Modbus and DNP3, and compromised remote access points.
Key Takeaways from the Guidance
1. Collaborative Effort: CISA, along with eight international agencies, has released this OT cybersecurity guidance to protect critical infrastructure.
2. Standardized Framework: The guidance utilizes the ISA/IEC 62443 standards framework, incorporating asset classification and 14 key tracking attributes.
3. Real-Time Monitoring: It integrates threat databases for continuous monitoring, particularly across the energy and water sectors.
A Systematic Approach to OT Asset Management
The guidance introduces a structured methodology based on OT taxonomies aligned with the ISA/IEC 62443 standards framework. Organizations are encouraged to categorize assets into:
– Zones: Logical groupings of assets sharing common security requirements.
– Conduits: Communication pathways with shared cybersecurity requirements between zones.
The framework emphasizes the collection of fourteen high-priority asset attributes, including:
– MAC addresses
– IP addresses
– Active communication protocols
– Asset criticality ratings
– Manufacturer and model information
– Operating systems
– Physical locations
– Ports and services
– User accounts
– Logging capabilities
Organizations are advised to implement both criticality-based and function-based classification methodologies to enhance risk identification and vulnerability management processes.
Development of Conceptual Taxonomies
CISA developed these taxonomies through collaborative sessions with 14 organizations across the energy sector’s oil and gas and electricity subsectors, as well as water and wastewater sector organizations. The taxonomies classify assets as:
– High-Criticality: Requiring stringent network segmentation and role-based access control.
– Medium-Criticality: Requiring robust monitoring and regular updates.
– Low-Criticality: Requiring basic security measures.
Integration with Threat Databases
The guidance emphasizes the integration of asset inventories with CISA’s Known Exploited Vulnerabilities (KEV) Catalog and MITRE’s Common Vulnerabilities and Exposures (CVE) database for continuous threat assessment. Organizations are encouraged to cross-reference inventories with the MITRE ATT&CK Matrix for ICS and implement real-time monitoring of process variables, including temperature, pressure, and flow indicators.
Building Resilient Architectures
By adopting this comprehensive approach, organizations can develop modern, defensible architectures while maintaining operational continuity, safety compliance, and regulatory requirements across critical infrastructure environments.
