Micro segmentation is a proven security strategy that works by dividing a network into much smaller and more secure segments. This helps in limiting the spread of a cyberattack in case of a breach thereby containing the event and its implications. Microsegmentation involves creating security zones around individual devices, applications, or services within an OT network thereby isolating them from other parts of the network. At its heart microsegmentation involves security via access denial.
In an OT environment, micro segmentation can be used to secure critical infrastructure systems including power plants, water treatment facilities, and manufacturing plants.
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4 key benefits of having Micro segmentation in an OT environment
1. Enhanced Security
micro segmentation significantly improves security by shrinking the attack surface area. In a worst-case scenario where an attacker manages to breach one segment, they would face additional barriers to gain access to other segments. Thus the mobility of a hacker or malware is significantly limited.
2. Improve operational efficiency
By segmenting network traffic and limiting the many broadcast domains, micro segmentation can lead to improved network performance and reduced congestion. It ensures the availability of dedicated bandwidth and resources to critical OT resources thereby optimizing their performance.
Micro segmentation enables security teams to deploy security policies at a granular level. This improves their ability to comply with standards such as IEC 62443 and NERC-CIP. By segregating sensitive systems and data, organizations can easily demonstrate compliance and even meet audit requirements.
4. Adaptability and Scalability
Micro Segmentation offers flexibility in adapting to and managing evolving network architectures. When new devices or services are added, they can be assigned to appropriate segments, thereby ensuring a secure, dynamic, and scalable network infrastructure.
Planning for implementing micro segmentation in an OT environment
Implementing micro segmentation in an OT environment requires careful planning, network (awareness and) visibility, and a thorough understanding of the operational requirements. To begin with, complete a thorough assessment of your OT environment and inventorize all your OT assets and segregate them based on criticality.
Follow these steps once the OT asset inventorization bit is complete
1. Understand the OT Architecture
Understand the interdependencies and communication patterns of all key systems and map them
2. Define segmentation policies
Using the initial assessment, determine the segmentation policies and access controls needed for each segment. Consider various factors such as security requirements, operational needs, compliance mandates, and any network or asset restrictions. Define rules for communication within and between segments to ensure a smooth flow of data. The policies should be so defined to improve network visibility and efficiency while minimizing any scope for latency.
3. Design network segments
Conceptualize a network segmentation plan that aligns with your segmentation policies and overall goals. Determine the boundaries and scope of each segment, factoring network topology, physical and logical separation, and traffic flow requirements.
4. Implement access controls
Deploy access control mechanisms including firewalls, switches, routers, and security appliances to enforce the segmentation policies defined in the earlier step. Configure the rules and policies to control traffic flow and restrict communication-based on the principle of least privilege in line with Zero Trust.
5. Establish adequate controls for monitoring and visibility
Implement network monitoring and visibility tools to gain an in-depth view of network traffic, segment interactions, and potential security incidents. This helps in identifying anomalies, detecting unauthorized communication attempts, preventing breach attempts, and ensuring ongoing compliance.
6. Test often and validate
Conduct thorough testing and validation of the implemented micro segmentation strategy frequently. Verify that the intended segmentation is working as per defined goals and principles without disrupting any critical or non-critical operations. Conduct penetration testing to discover any vulnerabilities or misconfigurations at that could impair the gains from micro segmentation.
7. Deploy segmentation controls
Deploy the micro segmentation controls gradually, starting from less critical segments and gradually moving towards the more critical ones to minimize any disruption. This approach will enable fine-tuning and adjustment of controls and rollout based on real-world operational scenarios.
8. Train staff and improve security sensitivity
Run training and awareness programs for OT and IT personnel involved in managing and operating the segmented network. Ensure that they understand the purpose, goals, benefits, and proper use of micro segmentation. Train them on incident response and handling procedures specific to segmented environments.
9. Monitor, maintain, and update
Continuously monitor all network segments, review access control policies, and update them as needed. Regularly assess the effectiveness of micro segmentation controls and adapt them to evolving threats and operational changes.
10. Regular auditing and compliance checks
Conduct regular and calendarized audits to assess the compliance of the micro segmentation implementation with relevant industry standards and regulations. Address any identified gaps or non-compliance issues promptly.
There are many ways to deploy micro segmentation in an OT environment taking into account factors such as goals, size of operations, security needs, and compliance mandates. One approach is to use network segmentation devices such as firewalls and switches as per the pre-defined segmentation architecture. Organizations can also use software-defined networking (SDN) technology for micro segmentation. SDN can be utilized to create virtualized networks. These networks can then be segmented and controlled way more easily.
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The best path to micro segmentation
The best approach for implementing micro segmentation in an OT environment will almost certainly depend on the specific needs of the organization and the security team involved. Based on the maturity of security practices, OT micro-segmentation can be fine to create a bigger sum of parts.
Micro segmentation is most certainly a valuable security strategy and tactic that can help to protect critical infrastructure systems and improve your security posture.
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