How-to guides

System hardening and CIS compliance: the complete guide

This blog will explore the importance of system hardening, and how you can implement CIS benchmarks to stay secure.

Tal Morgenstern | March 16, 2023

From development to testing, staging, and production, the majority of tech companies have several environments. This better enables the deployment of an error-free product into production. However, a functioning system does not guarantee the product will be secure. With new features constantly being introduced to improve product efficiency, integrations of multiple systems can introduce additional complexity and more threats to the environment. It is therefore important to adhere to best practices. 

CIS Benchmarks, the globally recognized security standards of the non-profit Center for Internet Security, aim to help organizations keep systems safe in an ever-changing threat landscape.

In this article, we will discuss why your production environments need to be CIS-compliant and the many benefits this offers.

Securing your infrastructure with system hardening

Prior to code or deliverables being pushed to production, code, system, and security tests are used to understand how new changes or releases will affect the production environment. But even if code undergoes rigorous application security testing prior to it going to production, the system or the infrastructure it is hosted on can still contain vulnerabilities that could lead to a security breach in the future.

Aligning with hardening guidelines such as CIS and NIST is key to protecting your infrastructure and systems as well as implementing continuous monitoring in order to ensure ongoing system security. System hardening involves following best practices and implementing controls using tools and techniques to reduce threats. This is achieved by strengthening the systems, network, and infrastructure.

One of the main advantages of system hardening is that it aids organizations in reducing the attack surface by eliminating weaknesses such as insecure configurations, risky logins, and weak data encryptions—which could lead to serious issues such as data breaches. In short, system hardening guidelines like CIS provide extensive information to help minimize potential loopholes and weaknesses that can be used to gain unauthorized access to the environment and thus avoid possible exploitation.

CIS Benchmarks in organizations

CIS Benchmark recommendations may require adjusting existing configuration settings or disabling services, functions, and accounts. This hardening covers different aspects of the infrastructure and provides a baseline for businesses to understand what needs to be implemented to make the environment secure.

CIS Benchmark hardening guidelines are even more specific, with different recommendations depending on the operating system. These extensive hardening guidelines provide a description of the area that needs to be hardened, specify the impact, and offer remediation guidelines as well as provide IT staff with references offering support and step-by-step instructions. 

System hardening has several focus areas. In addition to recommendations for your infrastructure, CIS also offers guidelines for security fine-tuning of applications and databases.

Focus areas of system hardening

The system hardening process may start with an audit of the environment to identify any gaps. This evaluation presents the company’s current security score and where it needs to be. Vulnerability scanners such as Tenable run CIS-specific template-based scans giving you visibility into your environment and indicating what still needs to be implemented.

This gap analysis or hardening is not limited to software. Let’s take a look at some equally important key areas of focus and examples for securing the environment and preventing attacks through system hardening:

  • Application
      • Remove default passwords and control access of application users.
      • Remove unnecessary components and functionalities, and maintain logs.
  • Database
      • Implement strict controls on privileged user accounts.
      • Encrypt the database to protect the information.
  • Operating systems
      • Configure operating system updates and patches, and automate the process.
      • Automated mechanisms for OS patching.
  • Networking
      • Ensure proper configuration of firewalls and that firewall rules cover all aspects.
      • Block insecure ports and protocols.
  • Server hardening
    • Make sure access control is aligned with the least-privilege principle.
    • Segregate servers and implement secure hosting.

The importance of system hardening

Even if you are using advanced technologies like endpoint detection and response (EDR) solutions to monitor the environment, following up on the best practices is still key when it comes to system hardening. It’s therefore important to implement security measures in addition and not rely solely on detection and prevention systems.

System hardening offers numerous advantages, including:

  • Improved security posture: System hardening increases the security score of the systems with security controls by reducing the attack surface.
  • Meeting security compliance standards and audits: A more refined, simplified environment with only the necessary components and functionalities will provide greater transparency and reduced complexity..
  • Improve system functionality: In hardening, it is recommended to disable services and functionalities that are not necessary for the operations that can be enabled by default. This eliminates many operational issues and limits the environment to only what is required.

Smaller organizations unable to invest heavily in security tools can still reduce risk by following CIS Benchmarks. Nonetheless, even with other security measures in place, hardening is still a must in order to secure the environment and reduce the risk of potential breaches that could lead to serious penalties and fines.

Because production systems are mostly exposed to the external environment, this poses a greater security risk compared to systems limited to internal use. Following CIS guidelines in the production environment and implementing controls are therefore crucial in order to reduce the attack surface.

An insecure production environment makes it an easy target for attackers looking to make lateral movements through privilege escalation. Organizations must therefore implement role-based access controls (RBAC) and least-privilege concepts. Providing privileged access to those who do not require it increases the risk of misconfiguration

For example, components, ports, and protocols that are no longer needed can be overlooked and could easily be used as backdoors. But you can block opportunities for attackers to compromise your system through:

  • Patch management
  • Disabling insecure ports and protocols
  • Control access management
  • Error handling


patch management best practices


Being compliant and maintaining compliance status

While hardening your infrastructure is sure to enhance the security of your organization, security is a continuous process that requires close monitoring even after hardening. No system is completely resistant to threats, especially when it comes to zero-day vulnerabilities.

System hardening is a mandatory requirement in most security audits. This can be achieved through fine-tuning of configurations, implementing additional controls like defense in depth, and introducing security policies and procedures. But maintaining the security of the production environment requires continuous monitoring. This will enable a better understanding of new threats, misconfigurations, and system weaknesses that may have been introduced since the initial deployment. It will also help to determine whether hardening mechanisms are still functional.

Watch: Risk-based vulnerability management for continuous compliance >>

The bottom line

While implementing CIS controls helps to safeguard assets in the environment in accordance with industry-standard practices, there is still the looming threat of unknown, zero-day vulnerabilities. When it comes to safeguarding the company infrastructure, the CIS Benchmarks can help organizations achieve protection from evolving threats. But this should also be complemented by monitoring and implementing a robust cyber risk management program to enhance the security of the environment and protect it from malicious actors.

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