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ICS Security Best Practices

Table of Contents

Industrial control systems (ICS) are vital to the operations of manufacturing and critical infrastructure organizations. ICS encompass industrial automation systems like SCADA, DCS, PLCs, HMIs, and more that monitor and control physical processes. While these systems provide major efficiency and productivity benefits, they also introduce serious cybersecurity risks if not properly protected.  In recent years, ICS security has become a major concern due to the rise of targeted cyber attacks aiming to disrupt critical operations. Malicious threat actors like nation-state groups and hackers are actively looking to exploit ICS environments. A successful attack could halt production lines, damage equipment, endanger employee safety, and cause substantial financial impacts. Manufacturing organizations rely heavily on their ICS staying online and being trustworthy. Any disruption to these systems would significantly affect the business. Preventing ICS security incidents needs to be a top priority. This article provides expert advice and a comprehensive list of ICS Security Best Practices manufacturing organizations should implement for properly securing industrial control systems against modern threats. Following these ICS security guidelines will help reduce risk and enable faster detection and response to any issues that may arise.

ICS Security Best Practices 1: Secure ICS Network Architecture

Having a secure network architecture is foundational to protecting industrial control systems. Legacy ICS environments were designed for safety and reliability, not security. The priority was keeping processes running. But exposing ICS systems openly makes them sitting targets. Here are essential cybersecurity best practices for building secure ICS network architecture:

  • Physically separate OT and IT networks – ICS networks should be air-gapped from the corporate environment. Limit connections between OT and IT to reduce attack surfaces. Air gaps prevent threats from spreading between environments.
  • Segment ICS networks into zones – Divide the OT environment into zones and restrict communication between them. This adds internal barriers to limit lateral movement after a breach.
  • Remove unnecessary legacy protocols – Deprecated insecure protocols like Telnet, FTP, and RPC provide pathways for attackers. Eliminate them if possible or filter access.
  • Utilize DMZs for external connections – Any external ICS connections should be through Demilitarized Zones (DMZs). DMZs prevent direct access to critical assets.
  • Authenticate all communication – Require authentication for all ICS network communication between assets. This ensures only authorized systems can interact.
  • Encrypt ICS traffic – Encrypt network traffic to prevent reconnaissance, data theft, and man-in-the-middle attacks. Use certificates or protocols like TLS and SSH.
  • Monitor data flows – Gain visibility into ICS communication patterns to detect abnormal behaviors indicating malicious activity.
  • Restrict device access – Only permit ICS devices to communicate with other systems necessary for their function. Block all other communication.
  • Utilize firewalls and ACLs– Manage ICS access with firewalls between zones and ACLs on endpoints. Allow only approved connections.

Proper network segmentation, protection of access points, and constraints placed on communication paths make lateral movement much more difficult for adversaries that breach the perimeter. Integrating these concepts will drastically improve ICS security posture.

ICS Security Best Practices 2: Protect ICS Endpoints

In addition to the network, robust protections need to be deployed directly on ICS assets like HMIs, PLCs, RTUs, and engineering workstations. Here are key measures to secure ICS endpoints:

  • Harden device configurations – Disable unused services, close open ports, remove default accounts/passwords, and implement vendor security recommendations.
  • Install compensating controls – Endpoint protection like antivirus, whitelisting, IPS can be implemented if they do not impact performance.
  • Manage accounts and privileges – Only provide user and application accounts necessary access. Enforce the principle of least privilege.
  • Require multi-factor authentication – Add an extra authentication factor beyond passwords for admin access. This prevents breached credentials.
  • Install security updates – Vendor security patches contain important vulnerability fixes. Prioritize patching critical issues.
  • Encrypt local storage – Utilize disk and removable media encryption to protect from data theft if assets are compromised.
  • Log endpoint activity – Capture event logs, security events, and system logs to improve detection and analysis. Forward to a SIEM.
  • Monitor file integrity – Detect malicious or unauthorized changes to devices like modified firmware or settings.
  • Utilize change management – Require documentation, review, testing, and approval before any configuration or software modifications.

Applying this combination of preventative and detective endpoint controls provides defense-in-depth that reduces the attack surface, increases visibility, and contains threats attempting to pivot laterally through the environment.

ICS Security Best Practices 3: Secure the ICS Supply Chain

The ICS supply chain introduces significant cyber risk. Vendors, integrators, and other third-parties have direct access to modify and install assets within the ICS environment. Manufacturers relying on the supply chain must take steps to validate, monitor, and control vendor access including:

  • Vetting suppliers – Review suppliers’ cybersecurity maturity, practices, and incidents related to products or services being provided.
  • Securing procurement – Employ measures to prevent supply chain tampering like chain of custody, signature verification, tamper-evident packaging.
  • Limiting vendor access – Only allow temporary secured remote access via VPN with MFA and sessions monitored in real time. No persistent connectivity.
  • Managing vendor credentials – Upon onboarding and offboarding, promptly issue, rotate, or revoke any vendor credentials and privileges to ICS systems.
  • Validating software integrity – Verify checksums and signatures of software or firmware from vendors to detect tampering or counterfeits before installation.
  • Isolating third-party connections– Require external-facing supplier systems integrate via a DMZ to prevent uncontrolled access to ICS environment.
  • Monitoring supplier systems – Detect abnormalities in vendor infrastructure that could indicate compromise such as C2 traffic or unusual data flows.
  • Coordinating disclosure – Maintain contacts and relationships to quickly report or receive vulnerability disclosures that impact supply chain.
  • Incorporating SLAs – Include security requirements, performance metrics, and breach responsibilities through contracts and service agreements.

Organizations are only as secure as their weakest link. While you can’t completely control vendors, taking steps to validate, monitor, and limit supplier access helps minimize risks they may introduce.

ICS Security Best Practices 4: Maintain Effective ICS Security Monitoring

Preventative controls will not block every attack. Manufacturers must maintain effective security monitoring across the ICS environment to quickly detect potential intrusions and operational anomalies. Key monitoring capabilities include:

  • Asset discovery – Inventory all ICS components to identify shadow IT and properly manage devices.
  • Network traffic monitoring – Analyze network patterns to detect unusual communication flows or malicious traffic.
  • Log aggregation – Centralize logs from all endpoints and infrastructure to enable holistic monitoring and correlation.
  • Behavior analysis – Detect deviations from normal ICS component behavior that could indicate compromise.
  • Threat intelligence – Incorporate latest threat feeds to get visibility into current high risk attack indicators.
  • Emergency response planning – Document response procedures for different incident scenarios from system failures to active intrusions.
  • Backups and redundancy – Ensure critical monitoring infrastructure has failover capabilities and backups if systems go down.
  • Tabletop exercises – Test detection and response capabilities through simulations and tabletop exercises modeling real-world incidents.
  • Maintenance and tuning – Continuously validate and optimize monitoring controls as the OT environment evolves.

Security monitoring provides visibility into the ICS threat landscape and delivers the necessary telemetry for effective incident response. However, logging and alerting infrastructure requires care and maintenance like any critical system. Don’t deploy controls and expect them to run smoothly forever.

ICS Security Best Practices 5: Prioritize ICS Vulnerability Management

  • New vulnerabilities – in ICS software and hardware are discovered regularly. The inability to remediate known security flaws leaves manufacturers exposed. Strong ICS vulnerability management entails:
  • Asset inventory – Maintain an up-to-date inventory of all software and hardware components to understand your attack surface.
  • Vulnerability scanning – Regularly scan ICS components to identify vulnerable services, missing patches, misconfigurations, and exploitable conditions.
  • Risk assessment – Analyze scan findings to evaluate vulnerability severity and potential impact on delivery of ICS functions.
  • Patch management – Test and install applicable patches for vulnerable software versions. However, prioritize patching based on risk due to potential compatibility/stability concerns.
  • Compensating controls – For vulnerabilities that cannot be directly patched, implement temporary compensating controls to reduce risk like increased monitoring or network segmentation.
  • Penetration testing – Conduct regular authorized penetration tests simulating real attacks to validate remediation efforts and uncover undetected flaws.
  • Third-party review – Utilize independent cybersecurity experts to review your program and identify potential coverage gaps.

New vulnerabilities will be introduced continuously by vendors. Proactive scanning combined with strategic mitigation of severe risks helps avoid disruption from compromise of known flaws.

ICS Security Best Practices 6: Implement ICS Incident Response Plans

Despite best efforts, ICS security incidents will inevitably occur through targeted attacks, insider threats, or even operational accidents. Incident response planning enables rapid containment, eradication, and recovery from ICS security events.

  • Dedicated team – Assemble and train a cross-functional team encompassing OT, IT, security, legal, and executives that can coordinate response efforts.
  • ICS expertise – Ensure the team has specialized knowledge in industrial control systems, relevant communication protocols, and potential impacts from disruptions.
  • Response procedures – Define detailed response procedures assigning roles, resources, communication channels, and playbooks tailored to different types of ICS incidents.
  • Notification triggers – Establish clear thresholds for when to declare an incident and escalate both internally and externally to parties like law enforcement.
  • Backup systems – Have redundant ICS networks or rapid restoration capabilities to recover compromised environments and maintain uptime.
  • Forensics capabilities – Collect forensic artifacts to determine root cause, scope of damage, and prevent reoccurrence without impeding restoration.
  • Incident reporting – Track details like anomaly timelines, mitigation steps, and lessons learned for audits, insurance claims, and enhancing future response capabilities.
  • Response exercises – Conduct simulated incident response exercises from detection through recovery to validate effectiveness of preparedness.

With operational technology, uncontrolled reactions can sometimes do more harm than the incident itself. Thoughtful planning and testing facilitates rapid, controlled response minimizing loss.

ICS Security Best Practices 7: Provide ICS Security Training

Technology alone cannot protect an ICS environment. The people interacting with and managing these systems play a major role in security. But ICS staff often lack necessary cybersecurity knowledge. An effective ICS security training program entails:

  • Role-based education – Tailor training programs to different roles like control engineers, technicians, operators based on their hands-on duties.
  • Incorporating policies – Explain policies to personnel so they understand the guidelines they must follow and why they exist.
  • Raising awareness – Provide general education on ICS cyber risks, social engineering, and how staff impact security posture.
  • Implementing training – Require cybersecurity training upon new hire orientation as well as recurring sessions to keep skills sharp.
  • Promoting accountability – Make individuals responsible and accountable for applying good security practices in their day-to-day activities.
  • Simulating threats – Run exercises like phishing simulations to condition staff and evaluate susceptibility to common threat vectors.
  • Encouraging reporting – Foster an environment where personnel feel comfortable reporting suspicious activity without repercussions.
  • Validating competency – Use quizzes and tests after training to evaluate efficacy and identify potential knowledge gaps to enhance curriculum.

The human element can make or break an ICS security program. An educated and alert workforce that makes security part of their routine activities will provide major benefits.

Work With a Qualified ICS Cybersecurity Partner

In the complex and critical realm of industrial control environments, securing your systems against emerging threats is not just a necessity but a strategic imperative. By adopting our proven ICS security best practices, you position your organization to better defend against modern threats, significantly diminishing the likelihood of operational disruptions and breaches. This enhanced security posture is crucial for manufacturers who recognize the importance of safeguarding their operations.

Manufacturing organizations trust Vumetric to secure their most vital OT systems and processes from modern cyber threats. Discover how we can help address your unique ICS cybersecurity challenges and requirements.

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