An Introduction to CIS Benchmarks: Best Practices for System Hardening

5 min readFeb 12, 2025

Photo by Philipp Katzenberger on Unsplash (Text Added)

Cybersecurity threats constantly evolve, and organizations must adopt robust security measures to protect their systems. One of the most widely used frameworks for system hardening is the CIS Benchmarks, developed by the Center for Internet Security (CIS). These benchmarks provide detailed, prescriptive guidance for securely configuring IT systems, from operating systems and cloud platforms to network devices and applications.

This guide will explore CIS Benchmarks, how they work, why they matter, and how organizations can implement them effectively.

What Are CIS Benchmarks?

CIS Benchmarks are security best practice guidelines designed to help organizations reduce security risks by establishing a hardened system configuration. These benchmarks are:

Consensus-driven — Developed through collaboration with experts in industry, government, and academia.
Regularly updated — Continuously refined to address emerging cybersecurity threats.
Applicable across technologies — Cover a broad range of IT environments, including operating systems, cloud platforms, databases, network devices, and applications.
Used for compliance — Align with regulatory standards like NIST, ISO 27001, PCI-DSS, HIPAA, and SOC 2.

How Are CIS Benchmarks Developed?

Each CIS Benchmark is developed through a multi-step consensus process involving cybersecurity professionals, vendors, and security practitioners. The process includes:

Research & Drafting — Security experts create draft configurations based on industry best practices.
Community Review — A global IT and security professional community reviews the drafts.
Public Comment — Open feedback is collected before finalizing the recommendations.
Publication & Updates — The benchmarks are published and updated periodically to reflect new threats and technologies.

Official CIS Benchmark documents are freely available in PDF format for non-commercial use, but CIS also offers automated tools for more straightforward implementation.

Figure 1 The Full Consensus Development Process (Getting to know CIS Benchmarks)

Types of CIS Benchmarks

CIS Benchmarks cover a wide range of IT systems. Some of the key categories include:

Operating Systems: Windows Server, Windows 10/11, Linux (Ubuntu, Red Hat, Debian, CentOS), macOS
Cloud Platforms: AWS, Microsoft Azure, Google Cloud Platform (GCP)
Databases: MySQL, PostgreSQL, MongoDB, SQL Server, Oracle DB
Network Devices: Cisco, Palo Alto, Juniper routers & firewalls
Applications & Containers: Docker, Kubernetes, Microsoft 365, Chrome, Firefox, Zoom

Complete list of available Benchmarks: https://www.cisecurity.org/cis-benchmarks

Each benchmark provides specific configuration recommendations to minimize vulnerabilities while maintaining system functionality.

Understanding CIS Benchmark Scoring

Each CIS Benchmark is divided into two categories:

Automated vs. Manual Items

Each CIS Benchmark recommendation is categorized by its assessment method, helping organizations distinguish between those that can be automatically evaluated and those that require manual validation.

Automated — The system’s state can be automatically evaluated using a tool such as CIS-CAT Pro Assessor. A pass/fail result can be generated without human intervention.
Manual — The recommendation requires manual review to determine compliance. A pass/fail result cannot be automatically determined because the configuration depends on environmental factors or requires contextual interpretation.

Note: Previously, these were referred to as Scored (now Automated) and Non-Scored (now Manual). The new terminology better reflects the assessment method rather than importance, as manual recommendations remain critical for security.

Security Levels

Level 1: Essential security settings that have minimal impact on system usability.
Level 2: More restrictive security settings, ideal for high-security environments but may affect system performance.

This tiered approach allows organizations to implement security measures based on risk tolerance and operational needs.

Benefits of Using CIS Benchmarks

Strengthening Cybersecurity Posture

By following CIS Benchmarks, organizations can reduce attack surfaces, close security gaps, and protect against common vulnerabilities.

Regulatory Compliance

CIS Benchmarks align with compliance frameworks like:

NIST Cybersecurity Framework
ISO 27001
PCI-DSS (for payment security)
HIPAA (for healthcare security)
SOC 2 (for service providers)

Many security audits include CIS Benchmark compliance checks as a key requirement.

Standardized Security Across IT Environments

CIS Benchmarks provide a unified security baseline for multiple technologies, making standardizing security configurations across large organizations easier.

Automated Hardening with CIS-CAT Pro

CIS-CAT Pro is a configuration assessment tool that automates checking compliance with CIS Benchmarks. It scans a system’s configuration and generates reports on:

Which settings comply with the benchmark
Which settings need to be changed to improve security
Remediation steps for misconfigurations

Note: CIS-CAT Pro is not free. It is available through CIS SecureSuite Membership, which provides access to additional security resources, automation tools, and compliance reports. However, CIS does offer a limited free version (CIS-CAT Lite), which provides basic benchmark scanning without advanced reporting features. (https://www.cisecurity.org/cis-securesuite)

Organizations can also use Ansible, PowerShell, and Terraform scripts to enforce CIS recommendations automatically.

How to Implement CIS Benchmarks

Step 1: Identify Relevant CIS Benchmarks

Determine which CIS Benchmarks apply to your environment (e.g., Windows, Linux, AWS).

Step 2: Assess Current System Configuration

Use CIS-CAT Pro, manual auditing, or security tools like Nessus to compare existing settings with CIS recommendations.

Step 3: Prioritize Security Level

Decide whether to implement Level 1 or 2 settings based on your security needs.

Step 4: Apply Configurations

To enforce compliance with CIS Benchmarks, organizations can use a variety of manual and automated methods, including:

Manual Configuration — Adjust system settings manually based on CIS Benchmark recommendations.
Group Policy (Windows) — Use GPOs to apply security configurations across Windows environments.
Scripting & Automation — Automate enforcement with Ansible (Linux), PowerShell, Terraform, or other configuration management tools.
Cloud Security Policies — Apply settings via AWS IAM policies, Azure Policy, or GCP Security Command Center.

CIS SecureSuite Membership Advantage:

Organizations with a CIS SecureSuite Membership gain access to official CIS Build Kits — pre-configured Ansible, PowerShell, and Bash scripts that streamline the implementation of CIS Benchmarks. These scripts allow fast deployment and consistent security hardening across large environments (https://www.cisecurity.org/cis-securesuite).

Step 5: Continuous Monitoring & Updates

Security settings should be continuously monitored and updated to align with the latest CIS Benchmark versions.

CIS Benchmarks vs. Other Security Standards

While CIS Benchmarks provide specific configuration settings, they are not the same as compliance frameworks like NIST, ISO, or PCI-DSS. Instead, CIS Benchmarks help organizations meet those standards by offering practical implementation steps.

NIST 800–53 (Risk management framework): CIS Benchmarks provide security control mappings.
ISO 27001 (Information security management): CIS Benchmarks help with technical security controls.
PCI-DSS (Payment security compliance): CIS Benchmarks assist with securing cardholder data environments.
SOC 2 (Security for service providers): CIS Benchmarks guide secure configurations.

Final Thoughts

CIS Benchmarks are a powerful tool for security hardening across IT environments. Whether you secure Windows servers, Linux machines, cloud platforms, or network devices, implementing CIS Benchmark recommendations can significantly reduce security risks and improve compliance.

Key Takeaways:

CIS Benchmarks provide step-by-step security hardening guides for various IT systems.
They help organizations meet regulatory requirements like NIST, ISO 27001, and PCI-DSS.
Automated tools like CIS-CAT Pro simplify compliance assessments.
Security teams should continuously monitor and update configurations based on new threats.

Organizations can proactively strengthen their security posture by adopting CIS Benchmarks in an increasingly hostile cyber environment.