Defense-in-Depth

• Glossar

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Defense-in-Depth:
A Comprehensive Approach for Robust IT and OT Security

Defense-in-Depth is a comprehensive security strategy aimed at protecting industrial networks by implementing multiple layers of security. This article explains why such a multilayered approach is essential for securing IT and OT infrastructures and how it can be successfully implemented, taking into account the specific needs and challenges of ICS/OT security officers and plant managers.

Just as a castle's defenses are layered, a factory should implement various interdependent security concepts.

The Necessity of a Multilayered Security Approach

In an era where single security measures are insufficient to fend off all types of threats, implementing a Defense-in-Depth strategy is crucial. This is especially true in the context of Industry 4.0, where the interconnection of facilities and the digitization of production processes introduce new security challenges. Challenges for ICS/OT security officers, production, and plant managers who face specific pain points in the industry:

• Complexity of networked systems: The increasing integration of IT and OT systems enlarges the surface area for cyber threats. Here, solutions and systems according to the leading industry standard ISA/IEC 62443-3 should be implemented.
• Protection of critical infrastructures: Failures or impairments in production can lead to severe financial and reputational damage. Every OT security attack represents a potential compliance incident.
• Requirements for system availability: High availability is crucial to avoid production downtimes. Any unplanned shutdown reduces operating results and noticeably decreases OEE.
• Lack of visibility and control: Traditional IT security solutions and processes are often not fully compatible with specialized OT systems and the requirements for plant availability.

Implementing the Defense-in-Depth Strategy

An effective Defense-in-Depth strategy takes into account technical, procedural, and organizational aspects. This includes developing an IT security strategy that is specifically tailored to the needs of industrial networks.

To address the mentioned challenges, the following solution approaches can be combined with the solutions from Indu-Sol: Complete action recommendation with additions for network access and alerting, taking asset management and security audits into account:

1. Extended inventory and risk analysis: Incorporate asset management and security audits to identify all network participants and verify their authorization status. Use Indu-Sol tools for detailed analysis and to create a comprehensive security profile of your OT network.
2. Implementation of Asset Management Solutions: Deploy a CM&SM system to ensure continuous monitoring of all network devices. Capture and manage information about devices, their configurations, and security status.
3. Establishing Security Audit Procedures: Conduct regular security audits to assess the security of your network and identify unauthorized or unknown devices. Indu-Sol supports you with the necessary tools and expertise.
4. Continuous Screening for OT Network Accesses (Logging): Implement a comprehensive system that records all OT network accesses, both authorized and unauthorized. The solution should allow these activities to be monitored and logged in real-time to immediately understand network traffic.
5. Setting Up Alert Systems: Establish an effective alert system that automatically activates in case of suspicious activities or security breaches. The CM&SM system, for example, can be configured to send immediate warning messages in the event of unauthorized access or other security-relevant incidents.
6. Updating Security Policies and Processes: Consider continuous monitoring and alerting as integral parts of your security policies. Ensure that your policies reflect the latest findings from logging and alert messages.
7. Expanding Training and Awareness: Supplement your training measures with topics such as recognizing and reporting suspicious activities based on logging data and alert messages. This strengthens security awareness throughout the company.
8. Adjusting Emergency and Response Plans: Develop clear procedures for handling alert messages, including steps for investigation, isolation, and remediation of security incidents. Ensure your team knows how to respond to different types of security alerts.

Conclusion
Defense-in-Depth is much more than the sum of individual security tools; it is a holistic approach that combines technical solutions with organizational and procedural measures. The specific challenges of ICS/OT security officers and plant managers require tailor-made solutions that allow seamless integration into existing industrial environments.

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