Full Report
The CI-Fortify guidance asks critical infrastructure operators to prepare to isolate vital OT during a cyber emergency. Answer seven questions to get a clear picture of your isolation readiness — and the gaps worth investigating next. The post Is Your OT Actually Isolated?A 5-Minute Self-Assessment appeared first on Waterfall Security Solutions.
Analysis Summary
# Best Practices: Critical Infrastructure (OT) Isolation Readiness
## Overview
These practices address the requirements for "Islanding" or isolating Operational Technology (OT) networks from IT networks and the internet during a cyber emergency. The goal is to ensure that critical industrial operations can continue to function safely and independently even if the enterprise IT environment is compromised by ransomware or other cyber threats.
## Key Recommendations
### Immediate Actions
1. **Identify Critical Islanding Points:** Map all physical and logical connection points between OT and IT/External networks where a "kill switch" or disconnection can occur.
2. **Review CI-Fortify Guidance:** Familiarize security teams with the joint guidance from CISA (US), ACSC (Australia), NCSC (UK), and CCCS (Canada) regarding critical infrastructure fortification.
3. **Audit Manual vs. Automated Disconnects:** Determine if isolation requires manual cable pulling, firewall rule changes, or automated triggers, and ensure the necessary personnel have physical access.
### Short-term Improvements (1-3 months)
1. **Dependency Mapping:** Identify all IT-based services that OT relies on to function (e.g., DNS, NTP, Active Directory, License Servers). Ensure these have local redundancies within the OT perimeter.
2. **Communication Redundancy:** Establish out-of-band communication channels (e.g., satellite phones, dedicated radio) for operators to use when the primary network is isolated.
3. **Draft Isolation Playbooks:** Create step-by-step procedures for transitioning to "Island Mode," including who authorizes the isolation and how to verify that the isolation is complete.
### Long-term Strategy (3+ months)
1. **Implement Hardware-Based Enforcement:** Move toward unidirectional gateways or data diodes to ensure that even during "normal" operations, the attack surface is physically limited.
2. **Regular Isolation Drills:** Conduct "Black Start" or "Island Mode" tabletop and functional exercises to validate that OT can run for extended periods without IT connectivity.
3. **Supply Chain Isolation:** Assess cloud-managed industrial components and implement local controllers to ensure a loss of cloud connectivity doesn't result in a loss of physical control.
## Implementation Guidance
### For Small Organizations
- Focus on physical isolation: Ensure you can manually disconnect the OT/IT bridge.
- Maintain up-to-date paper copies of network diagrams and emergency contact lists.
### For Medium Organizations
- Implement a dedicated "DMZ" between OT and IT to facilitate controlled isolation.
- Mirror essential services (like Active Directory) locally within the OT network so they don't break when the link to IT is cut.
### For Large Enterprises
- Automate isolation via Software Defined Networking (SDN) or managed switches, but retain a manual override.
- Deploy Unidirectional Gateway technology to eliminate the risks associated with vulnerable firewall configurations.
## Configuration Examples
*While specific CLI commands vary by vendor, the following logic applies:*
- **Firewall "Kill Switch" Profile:** Pre-configure a firewall rule base that denies all traffic between OT and IT zones, which can be activated with a single command or script.
- **Local NTP/DNS:** Configure OT controllers to point to a local GPS-based NTP clock rather than an external internet-based time server (e.g., `pool.ntp.org`).
## Compliance Alignment
- **NIST SP 800-82:** Guide to Industrial Control Systems (ICS) Security.
- **IEC 62443:** International standards for the security of Industrial Automation and Control Systems.
- **CI-Fortify (Joint Guidance):** The specific international framework for critical infrastructure resilience.
- **NERC CIP:** (For Power/Utility sectors) requirements for Electronic Security Perimeters (ESP).
## Common Pitfalls to Avoid
- **Hidden Dependencies:** Assuming OT will work without IT, only to find that the HMI (Human Machine Interface) requires a license check from an internet server to launch.
- **Remote Access "Backdoors":** Forgetting about cellular modems or vendor-installed maintenance links that bypass the primary isolation point.
- **Lack of Testing:** Having a plan on paper that has never been tested, leading to operational failure due to unforeseen software timeouts when the network is cut.
## Resources
- **CISA CI-Fortify Joint Guidance:** hxxps[://]www.cisa.gov/resources-tools/resources/joint-guidance-critical-infrastructure-operators
- **Waterfall Security Solutions OT Assessment:** hxxps[://]waterfall-security[.]com/lp/ot-network-isolation-self-assessment/
- **NIST OT Security Resource Guide:** hxxps[://]csrc.nist[.]gov/projects/ics-security