CIS Benchmarks Explained: A Comprehensive Guide to Security Hardening Best Practices

CIS Benchmarks

CIS Benchmarks are a globally recognized set of security hardening guidelines created and maintained by the Center for Internet Security (CIS). They provide consensus‑driven, vendor‑agnostic best practices for securing operating systems, cloud platforms, applications, services, and network devices.

They are developed through a community process involving:

• Security practitioners
• Government experts
• Industry specialists
• Tool vendors
• Auditors and compliance professionals

CIS Benchmarks are widely used across IT, security, compliance, and DevOps teams to reduce attack surface, support regulatory frameworks, and achieve baseline system security.

What CIS Benchmarks Include

Each CIS Benchmark provides:

1. Prescriptive Hardening Recommendations

These include step‑by‑step guidance, such as:

• OS configuration settings
• File permissions
• Logging requirements
• Network stack restrictions
• Authentication and authorization controls
• Service disablement recommendations

Example categories for an OS benchmark:

• Account and password policies
• Bootloader protections
• Kernel/hardening parameters
• Firewall configuration
• Logging and auditing standards

2. Scored vs. Unscored Recommendations

Scored controls:

• Affect the benchmark score
• Intended for automation and compliance evaluation
• Represent meaningful, measurable improvements to security posture

Unscored controls: 

• Good practices, but
• May break functionality or require environment‑specific decisions
• Provided for guidance but not counted toward compliance

Example:

• “Disable unused file systems” → Scored
• “Configure environment-specific banners” → Unscored

3. Levels of Stringency (Level 1 and Level 2)

Level 1

• Minimally invasive
• Strong security baseline
• Little to no impact on usability
• Suitable for most organizations

Level 2

• Stricter, often more disruptive
• Intended for environments requiring higher assurance
• May affect usability or break services
• Common in highly regulated or classified environments

This two‑tier system allows organizations to balance security and operational practicality.

Types of CIS Benchmarks

CIS provides benchmarks for a wide range of technologies:

Operating Systems

• Windows (various versions)
• Linux distros (Ubuntu, RHEL, CentOS, Amazon Linux, Debian, SUSE)
• macOS
• Solaris

Cloud Platforms

• AWS
• Azure
• Google Cloud Platform (GCP)
• Kubernetes (CIS Kubernetes Benchmark)
• Docker

Applications & Middleware

• Apache
• NGINX
• SQL Server
• Oracle DB
• PostgreSQL

Network Devices

• Cisco IOS
• Palo Alto NGFW
• Juniper
• F5 devices

Purpose of CIS Benchmarks

1. Reduce Attack Surface

By disabling unused services, hardening configurations, and enforcing least privilege.

2. Standardize Security

Provides a consistent configuration baseline across distributed environments.

3. Support Compliance Requirements

Many frameworks reference CIS Benchmarks directly or indirectly:

• SOC 2
• PCI DSS
• FedRAMP
• NIST 800‑53 / 800‑171
• HIPAA
• ISO 27001
• CMMC

CIS Benchmarks are often used as a “proof of hardening” or evidence for control implementation.

4. Enable Automated Hardening

Benchmarks include:

• YAML profiles
• Automated tooling references
• Mappings to CIS‑CAT (CIS Configuration Assessment Tool)
• Settings compatible with Ansible, Puppet, Chef, Terraform, and cloud APIs

How Organizations Use CIS Benchmarks

1. Baseline Creation

Teams align new system builds with CIS Benchmark Level 1 or Level 2 profiles.

2. Continuous Compliance

Integrating CIS checks into:

• CI/CD pipelines
• EDR/XDR policies
• Hardening scripts
• Cloud security posture management (CSPM) tools

3. Audit Preparation

System owners provide CIS‑CAT reports or CSPM findings to auditors as evidence of hardened configurations.

4. Security Operations

SOC analysts use CIS-hardening as a foundational element of endpoint protection and attack‑surface reduction.

CIS Tools That Support the Benchmarks

CIS‑CAT (Configuration Assessment Tool)

• Scans systems against CIS Benchmarks
• Generates compliance scores
• Produces audit‑ready reports

CIS Hardened Images

Pre‑hardened cloud VM images available on marketplaces (AWS, Azure, GCP).

CIS WorkBench

A platform where practitioners collaborate and download benchmark resources.

Why CIS Benchmarks Matter for Security Teams

They help prevent entire classes of attacks:

• Lateral movement reduction
• Privilege escalation hardening
• Remote exploitation barriers
• Credential theft mitigation
• Script execution and service misuse protections

They align business and technical security goals:

• Measurable
• Auditable
• Repeatable
• Automatable

They provide a common language across IT and security:

• System owners
• Engineers
• Compliance teams
• Auditors

Summary

CIS Benchmarks are comprehensive, consensus‑driven best practices for securing systems, applications, and cloud infrastructure. They include:

• Scored and unscored controls
• Level 1 and Level 2 profiles
• Hardening guidance for a massive range of technologies
• Tools for assessment and automation

They play a crucial role in baseline security, compliance, and proactive threat reduction for organizations of all sizes.