CIS Benchmarks

CIS Benchmarks are standardised Security Hardening guidelines developed by the Center for Internet Security (CIS) for securing operating systems, applications, cloud platforms, network equipment and infrastructure components. Within modern OT, ICS and IT OT Convergence environments, CIS Benchmarks are used to configure systems more securely and reduce the attack surface.

The benchmarks contain concrete technical configuration guidelines for:

• servers
• workstations
• hypervisors
• cloud platforms
• containers
• network equipment
• databases
• industrial systems

Within industrial environments, CIS Benchmarks play an important role in:

• hardening
• Compliance
• secure baselines
• risk reduction
• OT segmentation
• Cybersecurity Governance

⚙️ What are CIS Benchmarks

CIS Benchmarks are community-driven Security Standards developed by:

Center for Internet Security (CIS)

The guidelines are produced by security specialists, vendors and industry experts.

Goals:

• secure default configurations
• reducing attack surface
• minimising misconfigurations
• raising cyber resilience
• standardising hardening

CIS Benchmarks are available for hundreds of technologies.

🏗️ Structure of CIS Benchmarks

A benchmark contains technical configuration controls.

Typical structure:

Example:

Disable unnecessary services

The benchmarks contain concrete technical settings.

📡 CIS Controls versus CIS Benchmarks

CIS Benchmarks are often confused with CIS Controls.

CIS Benchmarks are operational and configuration-focused.

🧠 Security baselines

CIS Benchmarks are used as a security baseline.

A baseline defines:

• permitted configurations
• minimum security settings
• standard hardening
• compliance requirements

Benefits:

• consistent configurations
• easier auditing
• lower risk of misconfiguration

Within OT, baseline management is essential because of long lifecycles.

🔒 Hardening of systems

CIS Benchmarks support Hardening of:

Many measures are directly relevant for industrial environments.

⚡ CIS Benchmarks within OT

Within OT, CIS Benchmarks are applied to:

• SCADA servers
• historians
• engineering stations
• hypervisors
• edge gateways
• Windows HMIs
• Linux OT servers
• container platforms

Important OT goals:

• reducing attack vectors
• protecting legacy infrastructure
• limiting lateral movement
• raising availability

🖥️ CIS Benchmarks for Windows in OT

Windows systems are dominant within many OT environments.

Important benchmark categories:

For OT systems, changes must be tested carefully because of process impact.

🐧 Linux hardening

Many modern OT platforms run Linux.

Examples:

• edge gateways
• Docker
• Kubernetes
• Soft PLC
• IoT gateways

Important Linux hardening:

• SSH security
• kernel parameters
• file permissions
• Audit Logging
• package management

☁️ Cloud and container security

CIS Benchmarks play a major role within cloud-native OT.

Available benchmarks:

Important for:

• edge orchestration
• IIoT platforms
• hybrid cloud OT

📦 Docker CIS Benchmark

The Docker benchmark covers:

• privileged containers
• image signing
• namespace isolation
• filesystem security
• runtime restrictions
• logging
• API security

Important within containerised OT architectures.

☸️ Kubernetes CIS Benchmark

Within Kubernetes environments, the benchmark covers:

For OT clusters, additional Real-time requirements are important.

🧩 Hypervisor hardening

Hypervisors are crucial within Virtualisation environments.

CIS Benchmarks exist for:

• VMware ESXi
• Hyper-V
• cloud virtualization

Important considerations:

• management isolation
• Secure Boot
• RBAC
• logging
• encrypted storage

Within OT, hypervisors are often part of critical infrastructures.

📡 Network equipment and switches

CIS guidelines also exist for:

• routers
• firewalls
• switches

Important measures:

• disabling unused ports
• management ACLs
• SNMP hardening
• secure management protocols
• logging

Within industrial networks, important for:

• Industrial Switch
• Router
• Firewall

🔄 CIS Benchmarks and compliance

CIS Benchmarks support compliance with:

Many auditors use CIS Benchmarks as a reference.

⚠️ OT challenges in hardening

OT systems differ significantly from IT systems.

Issues:

Therefore, benchmarks must be applied carefully.

🧪 Testing and validation

Hardening within OT requires extensive validation.

Key steps:

1. OTAP testing
2. Vendor validation
3. Process impact analysis
4. Performance testing
5. Recovery testing

Especially for:

• SCADA
• historians
• PLC engineering stations
• real-time systems

🛡️ Security versus availability

Within OT, there is tension between security and availability.

Examples:

OT hardening therefore requires risk-based trade-offs.

📉 Common benchmark categories

Identity & Access

• strong passwords
• MFA
• account lockout
• Least Privilege

Network Security

• firewalling
• segmentation
• secure protocols
• Port Security

System Hardening

• minimising services
• patching
• secure boot
• Application Control

Monitoring

• logging
• auditing
• SIEM integration
• event monitoring

🖥️ CIS-CAT

CIS also provides tooling:

CIS-CAT Pro Assessor

Functions:

• benchmark scanning
• compliance checks
• configuration validation
• reporting

Within OT, scanning must be performed cautiously to avoid disruptions.

🔒 CIS Benchmarks and Zero Trust

CIS Benchmarks support modern security models such as:

• Zero Trust
• Microsegmentation
• least privilege
• Defense in Depth

Important within converged IT/OT networks.

☁️ Edge Computing and CIS Benchmarks

Within Edge Computing, benchmarks are used for:

• edge gateways
• Linux devices
• containers
• Kubernetes edge
• IoT devices

Edge environments often require additional attention to:

• physical security
• remote management
• secure provisioning

🧠 CIS Benchmarks and OT cybersecurity

Within industrial cybersecurity, benchmarks support:

• attack surface reduction
• Ransomware prevention
• segmentation
• secure Remote Access
• compliance

Often combined with:

• Application Whitelisting
• EDR
• IDS
• Security Monitoring

🏭 Practical applications

Manufacturing

Use for:

• SCADA hardening
• Windows baselines
• hypervisor security

Energy supply

Applications:

• substation hardening
• OT server security
• secure Virtualisation

Water sector

Use for:

• Telemetry servers
• Historian security
• remote access hardening

Building Automation

Securing:

• BMS
• HVAC servers
• edge gateways

📈 Trends and developments

Important trends:

• cloud-native benchmarks
• container security
• OT hardening automation
• continuous compliance
• policy as code
• AI-assisted hardening

CIS Benchmarks evolve in step with modern OT architectures.

🎯 Conclusion

CIS Benchmarks form an important technical basis for hardening and cybersecurity within modern IT and OT environments. By providing standardised configuration guidelines, the benchmarks help organisations reduce risk, increase cyber resilience and support compliance.

Within IT OT Convergence, CIS Benchmarks play a growing role in securing virtualisation platforms, cloud-native OT, edge computing and industrial infrastructures.

Successful application within OT, however, requires careful validation, Risk Assessment and alignment with operational availability requirements.