Most server operating systems are designed with functionality in mind rather than security. This means they often come with unnecessary services, open ports, and default configurations that create exploitable weaknesses. One of the most effective ways to prevent cyber threats from exploiting these gaps is through structured security hardening strategies, ensuring systems are resilient against evolving threats.
What You Will Learn
- Why Server Hardening Matters
- Types of Hardening Tools
- How to Choose the Right Tool
- Best Practices for Hardening
- The Role of Automation
- Industry Standards and Compliance
What Are Server Hardening Tools?
The system hardening process reduces a system’s attack surface by securing the configurations of the system’s components (servers, applications, etc.). By default, system components are not secure. Hardening removes unnecessary functionality. Organizations should establish different hardening policies for each system component, aiming to be as granular as possible (differentiating components by type, role, version, environment, etc.).
System hardening has become a mandatory requirement in every regulation. By implementing a good hardening policy based on best practices from organizations such as CIS Benchmarks and DISA STIG, the risk of vulnerabilities and breaches can be significantly reduced.
Why Is Server Hardening Essential for IT Security?
Organizations implement different server hardening benchmarks for each system component, differentiating components’ type, role, version, environment, etc. to reduce their security risk.
Hardening has become a mandatory requirement in every regulation. Therefore, establishing a robust hardening policy is no longer open to debate, and there are security hardening best practices that organizations must follow (e.g., CIS Benchmarks and DISA STIG).
Understanding Server Hardening Stages
When it comes to the different types of system hardening measures, ensuring a robust and granular plan for compliance, the Center for Internet Security (CIS) guidelines play a vital role. Its CIS Benchmarks outline a set of best practices for securing IT systems, including servers, through robust operating system hardening (OS hardening) and application hardening guidelines.
The CIS guidelines offer detailed recommendations for system configuration, access controls, authentication mechanisms, and vulnerability management, including the regular application of updates and patches. By adhering to CIS Compliance, organizations can take a proactive approach to safeguarding critical data and maintaining a strong defense against evolving cyber threats.
After establishing a hardening policy, there are three stages you must complete to achieve baseline hardening:
Stage 1 – Testing
Testing is a critical phase in server hardening where baseline configuration changes should not be applied directly to avoid extensive damage. Despite hardening best practices advocating for disabling potential attack vectors, some specifications may be challenging to implement due to their role in ongoing server and application operations. To determine enforceable rules, a thorough understanding of network dependencies is essential. The testing stage involves creating a simulation of the network environment to accurately assess the impact of each rule enforcement. Although it is the most challenging and resource-intensive stage, it is crucial for preventing production outages if executed improperly.
Stage 2 – Enforcing
Following the completion of testing for each configuration change’s impact, a reassessment of the policy is necessary to determine the appropriate course of action for each affected rule.
Stage 3 – Monitoring
Continuous monitoring is crucial for maintaining a compliance posture, preventing setbacks, and adapting to the dynamic nature of organizational networks. With the constant changes in applications and hardware, it’s essential to promptly address intentional or unintentional configuration changes to uphold compliance standards.
Patching and updating your systems is a crucial security practice, but it’s not a silver bullet. Having proper tools for performing robust Server hardening and achieving compliance is highly recommended if you are dealing with large, complex environments.
Types of Server Hardening Tools
There are four groups of tools you should check before starting a hardening project:
- Compliance scanners
- Hardening automation tools
- Configuration Management
- Free open-source tools
Each type of tool offers a solution for a different stage in the hardening project:
| Testing | Enforcing | Compliance monitoring | |
| Hardening automation tools | V | V | V |
| Configuration Management tools | V | V | |
| Compliance Scanners | V |
Compliance Scanners – Assessing Security Posture
Features
Compliance Monitoring – only
Description
Compliance scanning focuses on assessing adherence to a particular compliance framework (e.g. CIS Benchmarks, DISA STIG). Compliance scanners generate a report indicating how well a system is hardened in relation to a compliance framework. Compliance tools can be used as complementary tools for assessing hardening, but they are not server hardening tools.
Hardening software typically refers to the process of strengthening the security of a system or application rather than specific software products. However, various tools and utilities can aid in the hardening process. These tools are often used to automate security configuration and monitoring. Here are a few examples:
- Tripwire Configuration Manager – gives you the ability to view all your assets’ configuration and compliance status of all your assets in a single reporting environment.
- Qualys – provides configuration scanning and simplifies workflows to address configuration issues.
- NNT SecureOps – provides intelligence change control and automation. Audits and automates continuous compliance. Provides real-time detection for suspicious changes.
- Tenable Nessus– Provides audit and compliance scanning of computing assets according to the CIS benchmarks. Custom baselines can be created and customized.
- CIS-CAT Pro – The CIS-CAT Pro Assessor evaluates a system’s cybersecurity posture against recommended policy settings. The tool helps organizations save time and resources by supporting automated content with policy-setting recommendations based on the globally recognized CIS Benchmarks.
Hardening Automation Tools – Automating Security Hardening
Features
Testing, enforcing, monitoring
Description
Hardening automation tools offer a complete hardening solution. They transform this tangled process into a ‘click-of-a-button’ task. Using hardening automation tools, you won’t need to write a single script or have any specific expertise.
They perform the entire testing procedure automatically by learning your infrastructure’s dependencies and reporting the potential impact of each configuration change. Only this feature alone can save most of the time and resources invested in the hardening project, making hardening automation tools preferable in terms of ROI.
Following the testing phase, hardening automation tools will also implement your policy on your entire production, using a single point of control. This dramatically eases the enforcement task and minimizes the possibility of human error. The whole configuration orchestration procedure is easy and controlled from a single point of control.
Finally, hardening automation tools will monitor your network and remediate any undesired changes in compliance posture. It will alert and correct configuration drifts and be reactive to structural changes of the network (setting up new machines or killing old ones). This will help you maintain a robust compliance posture.
Hardening automation tools have all the capabilities of Security Configuration tools and Compliance Scanners, in addition to the ability to perform impact analysis.
Tools: CalCom Hardening Suite (CHS)
How to plan and manage a hardening project. Read our exclusive guide to get ahead
Configuration management tools
Features: Enforcing, monitoring
Description
According to NIST, security configuration management (SCM) can be described as “The management and control of configurations for an information system with the goal of enabling security and managing risk.”. Configuration management tools can help enforce policies in a basic level but achieving robust hardening and compliance is very challenging as they are not server hardening tools.
By using SCM tools, you’ll be able to:
- Enforce your desired policy, enabling you to configure your infrastructure to your desired state.
- Easily enforce configuration changes throughout the infrastructure from a single point of control.
- Choose the version you’re working with.
- Easily make changes in code.
- Keep track of the changes made and who made them.
- Approve or reject the change request.
- Reporting and recording the configuration status.
Tools
- Ansible – Allows the user to control and develop automation in the IT network
- Chef – Automates application delivery, infrastructure configuration, and compliance auditing.
- Puppet – Open source infrastructure automation platform
- Microsoft System Center Configuration Management – Provides remote control, patch management, software distribution, operating system deployment, network access protection, and hardware and software inventory control.
- SolarWinds Network Configuration Manager Manages network compliance, network automation, configuration backup, and vulnerability assessment.
Open-source server hardening tools:
- Salt Project – Automated infrastructure management with data-driven orchestration, remote execution, and configuration management.
- Microsoft Security Compliance Toolkit 1.0 – Enterprise security tools that enable administrators to download, analyze, test, edit, and store Microsoft-recommended security configuration baselines for Windows and other Microsoft products.
- Hardening auditor– Scripts for comparing Microsoft Windows compliance with the ASD 1709 & Office 2016 Hardening Guides.
- Windows Exploit Suggester Next Generation – Provides a list of vulnerabilities for which the OS is vulnerable, including any known exploits for these vulnerabilities.
- Privesc – Windows PowerShell script for locating misconfiguration issues that can lead to privilege escalation.
- Windows-privesc-check – Standalone Windows executable that searches for misconfigurations allowing privilege escalation for unauthorized users.
Key Factors When Selecting a Server Hardening Tool
- Compliance Support: Ensure the tool aligns with industry standards, such as CIS Benchmarks, DISA STIG, or other relevant regulatory requirements.
- Ease of Use & Integration: Select a solution that integrates smoothly with your existing infrastructure and is easy to deploy and manage.
- Scalability: Opt for a tool that can support your organization’s growth and adapt to dynamic environments.
- Automation Capabilities: Look for tools that automate testing, enforcement, and monitoring to minimize manual effort and reduce human error.
- Minimizing Operational Disruption: Hardening changes can break applications or disrupt critical services. Select a tool that helps assess potential risks before implementing changes and enables safe rollbacks if issues arise.
- Testing & Impact Analysis: A strong tool should provide ways to test security policies in a controlled environment before enforcement. Look for features like automated testing, sandboxing, or impact analysis to prevent unintended outages.
- Remediation & Continuous Monitoring: A good hardening tool should not only enforce policies but also detect and correct configuration drifts.
- Customization & Flexibility: Ensure the tool allows granular policy adjustments to fit different server roles, environments, and security needs.
Key Takeaways
- Server hardening is essential
- Manual hardening is challenging
- Different tools serve different purposes
- Automation improves efficiency
- Continuous monitoring ensures security
CalCom Hardening Automation Solution
CalCom Hardening Suite (CHS) is a hardening automation platform designed to reduce operational costs and enhance the security and compliance posture of the infrastructure. CHS eliminates outages and reduces hardening costs by automating every stage in the hardening process:
- Impact analysis: Indicating the impact of a security hardening change on the production services.
- Policy implementation: After setting a policy based on the impact analysis report, CHS will implement each policy on the correct machine from a single point of control.
- Compliance: CHS will monitor your compliance posture, alert you to configuration drifts, and remediate them as needed. CHS will ensure your compliance level remains high in the dynamic, ever-changing infrastructure, so you won’t need to perform hardening from scratch a few months post your initial hardening project.
