OS & Environment Hardening: Why System Security Matters & Key Considerations

In the following paragraphs, we’ll discuss what hardening means, the benefits and disadvantages it brings, and where to begin in the process of securing an operating system. Let’s first understand what the hardening process is. The concept of hardening, in relation to computing, is when the system is made more secure through the use of restricting policies, enforcing configurations, and using tools to detect and reduce the system’s vulnerabilities. Hardening can be performed at any time, but it is best practice to harden your operating system prior to deploying to production or connecting it to a network. A gap that is discovered during SOC 2 audits is finding that infrastructure is not patched as frequently as expected, or is not patched to the expected version. In our experience auditing hundreds of organizations for SOC 2 compliance, proper OS hardening is a strong preventative control.

Hardening Your Operating System & Environment: Where to Start

Understanding the system’s vulnerabilities is essential to reducing its attack surface. Begin by assessing the purpose of the infrastructure that you are hardening. Hardening expectations will be different for a system that is not public-facing versus one that is public-facing. Next, determine what compliance framework(s) align with your company. It’s a good idea to perform a risk assessment for your system, too. This should identify areas with the most risk. Once the risks of your system are assessed, consider the extent of hardening that is appropriate for the organization. As a plan is developed to harden the system, rank the level of impact on business operations and day-to-day usage for each improvement made. Organize the hardening improvements into categories of low, medium, and high impact and risk in order to best assess where to begin.

The level of impact will be unique to each entity; however, here are examples:

• Low Impact: Enable encryption and set up a strong passphrase.
• Medium Impact: Implement two-factor authentication, install a password manager tool, and restrict removable media and USB devices.
• High Impact: Configure exploit protection and calibrate network activity.

 

Benefits & Disadvantages of Hardening your OS & Environment

Hardening the operating system improves security and reduces the system’s attack surface. When the system’s attack surface is smaller, the risk of exploitation, malware being injected, or an attacker gaining entry into an entity’s environment is smaller as well.

Well-architected systems can have design gaps and vulnerabilities. Default settings on out-of-the-box operating systems are made to cater to the largest customer base. Therefore, hardening includes researching and updating default settings to better fit the organization. Hardening is expansive and includes performing modifications to the system based on the risk of the system, the organization, the industry, etc.

While securing a system is beneficial, it is also important to remember that no system is 100% secure. Hardening is intended to lower your risk, not remove it entirely. Understand the potential consequences before making changes. Some of these potential consequences could include:

• Lessening the convenience of using the operating system.
• Increased time to monitor and maintain the configurations, settings, and tools installed.
• Purchasing tools and allocating time toward hardening can be expensive.
• Existing systems may function differently after hardening.

 

Key OS and General Hardening Considerations: An Auditor’s Perspective

There isn’t a single checklist to apply to environments, but similar concepts can be used as a baseline when hardening your system.

Default Settings

There are legacy programs and features that come enabled on your operating system. Default services may have known or unknown vulnerabilities. By disabling them, the risk is mitigated for that service in particular. If the relevance of the feature is undetermined, consider turning it off until it is required.

• Consideration 1: Consider removing or disabling network protocols that are not required and assessing the requirement of remote access programs as well, especially those that do not encrypt their communications.
• Consideration 2: Disable unnecessary accounts that may be built into the OS.
  • Guest accounts are often included and enabled by default (potentially without a password requirement), along with root-level accounts, local accounts, and accounts for network services.
  • Because these accounts are default, they have a default naming convention.
  • Disabling or modifying these accounts lessens the risk that they will be targeted by attackers.
•  Consideration 3: On Windows OS, the default feature of AutoPlay is enabled. This can be disabled to prevent [potentially malicious] files from automatically opening when a USB is plugged in.

Access & Authentication

The concept of “least privilege” isn’t just for administrators. Access should be restricted for administrators and non-administrative users by evaluating access to files and folders individually. When managing access, shared accounts create a blind spot for accountability and should not be used.

• Consideration 1: In order to establish what roles should (and should not) have overlap, create a segregation of duties matrix.
  • Place titles or groups along one axis and system access along the other.
  • This matrix will provide a visual to detect roles that should have more restricted access and is beneficial for provisioning or modifying user access.
  • Understand and define company roles, including ownership of compliance responsibilities and governance processes within the organization.
• Consideration 2: Default passwords should be changed, especially those with the purpose of management or maintenance. Also, enforcing multi-factor authentication adds additional security.
• Consideration 3: Establish the entry points into the environment to restrict access. Configuring security groups and firewalls can protect from unauthorized access.

Learn more about password issues and best practices from our blog on NIST password guidelines.

Asset Protection

An inventory of assets will guide management to the assets that are most critical and, therefore, should have the most layers of protection. By patching the operating systems of assets, they will remain up to date with the latest security features and bug fixes. Consider the extent of testing and approval that is required prior to patches being implemented into production. Additionally, installing and running anti-malware software increases the chance of detecting vulnerabilities and encrypting data at rest and in transit protects the data if attackers gain unauthorized access.

• Consideration 1: Determine the patch frequency for devices within the environment.
  • Establish if patches will be installed automatically or manually, and also determine who is responsible for applying the updates.
• Consideration 2: Install anti-malware on devices within the environment and consider the implementation of intrusion detection software (IDS) and intrusion prevention software (IPS) to detect attacks.
• Consideration 3: Determine which level of encryption is right for you: 3DES (triple DES), AES, and Rivest-Shamir-Adleman (RSA) when encrypting data at rest and in transit.

Continuous Monitoring

While unnecessary programs and features are turned off during hardening, there are features to consider enabling in order to harden your system. Enabling audit policies can be helpful by logging activity and authentication attempts. The act of hardening is primarily enforcing preventative processes, but by enabling detective logging of user activity, the system can be more secure with the ability to review historical trends and detect if brute force attacks are being attempted. However, the storage to retain logs and the responsibility of reviewing them should be evaluated and assigned.

Perform vulnerability assessments and penetration testing to detect vulnerabilities, missed patches, and changed configurations that can indicate if additional hardening procedures should be performed.

Learn more about vulnerability and penetration testing from our related blogs:

• External Penetration Testing & SOC 2 Reports: How Are They Related?
• Types of Penetration Tests: A Look at Different Pentest Techniques & Tools
• Vulnerability Scanning: Importance of Vulnerability Scans in SOC 2 Audits
• Vulnerability Management Program: Insights From an Auditor
• Vulnerability Management Maturity Model, Procedures, Threats, & More

 

What Is the Difference Between OS Hardening & Patching?

Patching is a component within the concept of hardening. While patching is an important aspect, hardening includes additional security-related tasks such as the following:

• Limiting access.
• Disabling unnecessary default features.
• Enabling only the ports and services that are required.

Next Steps: Putting OS Hardening Into Practice

Hardening is a vast topic and should be tailored to the environment in which the operating system resides. Research and investigation into the hardening processes, along with their impact on the environment, should be performed by appropriate individuals. Additionally, there are checklists available for common system configuration baselines for cybersecurity through companies such as the Center for Internet Security (CIS) and the National Institute of Standards and Technology (NIST).

Linford & Company is an independent CPA firm that specializes in a variety of audit services, including SOC 1 and SOC 2 audits. If you have further questions, please review our website and contact us to see how we can further assist you and your organization.

Check out our other related articles on security:

• What is Endpoint Security? Why is it Important?
• Enterprise Security — 5 Steps to Enhance Your Organization’s Security
• What is Containerization? Security & Benefits

This article was originally published on 7/27/2022 and was updated on 1/7/2026.