Every new server, router or application deployed in a company is like a newly built house. The manufacturer delivers it with maximum functionality and ease of initial startup in mind. In practice, this means that all doors are open, windows are ajar and the key to the main door lies under the doormat, labeled “admin/admin.” The default configuration is optimized for convenience, not security. Leaving systems like this is like posting a banner that says “Welcome, open 24/7” to any cybercriminal.
In response to this fundamental risk, a discipline known as hardening, or hardening of systems and infrastructure, has emerged. It is a methodical and continuous process of identifying and eliminating unnecessary risks by reducing the so-called attack surface. Hardening is nothing more than systematically closing open windows, replacing temporary locks with approved ones, installing an alarm system and building a solid fence. This is the absolute foundation on which the entire cyber security strategy is based. Without a solid, “hardened” foundation, even the most expensive, advanced defense systems will stand on clay legs.
Shortcuts
- What is hardening and why is it the absolute foundation of cyber security?
- What are the main areas and categories that hardening focuses on?
- What is server hardening and what are the key actions to be taken?
- How to effectively secure network devices such as routers and switches?
- What are standards and benchmarks, such as CIS Benchmarks, and how do they help in hardening?
- How does nFlo help organizations implement a comprehensive hardening strategy?
What is hardening and why is it the absolute foundation of cyber security?
Hardening (hardening) is the process of configuring a system or device to minimize its vulnerability to attacks. The goal is to reduce the attack surface by disabling unnecessary features, removing redundant software, implementing strong access controls and using secure configurations. This process applies to every element of the IT infrastructure - from servers and workstations, to network devices and firewalls, to databases and applications.
It is the foundation of cyber security because it works at the most basic level - eliminating or making it more difficult to exploit potential attack vectors before they are discovered. Instead of relying solely on systems to detect and block active attacks, hardening makes a system inherently more difficult to compromise. Even if an attacker finds a way to bypass the firewall, a “hardened” target server, stripped of unnecessary services and with strong access controls, can effectively fend off further attempts.
In practice, the better the hardening process is carried out, the less work detection and response systems (such as SOCs) have to do. A smaller attack surface means fewer potential entry points, fewer alerts generated and less risk of a successful intrusion. It’s a proactive investment that pays dividends in the form of increased resilience and reduced operational risk.
📚 Read the complete guide: NIS2: Kompletny przewodnik po dyrektywie NIS2 - obowiązki, kary, terminy
What are the main areas and categories on which the hardening process is focused?
The hardening process is a holistic process that should encompass the entire IT infrastructure. It can be divided into several key areas, each of which requires a specific approach and set of best practices.
-
Operating system hardening: Applies to both servers (Windows Server, Linux) and workstations. Includes, among other things, installing only the necessary roles and functions, configuring security policies, managing user privileges and enabling auditing mechanisms.
-
Hardening of network devices: Focuses on securing routers, switches, Wi-Fi access points and firewalls. Key activities include changing default passwords, disabling unsafe management protocols and network segmentation.
-
Application hardening: Every business application, whether purchased or developed internally, should be “hardened.” This process includes, among other things, secure configuration, removal of default accounts and regular updates.
-
Database hardening: Focuses on protecting database systems (e.g. SQL Server, Oracle, PostgreSQL) by controlling access, encrypting data, enabling detailed logging and removing unused accounts.
-
Physical Hardening: While often overlooked in the digital context, this includes securing physical access to server rooms, patch cabinets and other key infrastructure components.
What is server hardening and what are the key actions to be taken?
Servers are the heart of most corporate infrastructures, storing and processing the most valuable data. Getting them “hardened” properly is absolutely critical to security. This process should begin even before the server is deployed in production.
The first step is to create a secure base image (golden image). Rather than installing each server from scratch, a master “hardened” operating system image should be prepared with all the necessary security configurations, policies and patches installed. Each new server is then deployed from this trusted image, ensuring consistency and repeatability.
Key server hardening activities include:
-
Installation of the minimum required number of roles and functions: If the server is to be a file server, it should not have the Web server (IIS) role installed.
-
Configure local security policies: Implement strict policies on password complexity, account lockout after failed login attempts, and session timeouts.
-
Implement the principle of least privilege: Users and service accounts should have only those permissions that are absolutely necessary to perform their tasks. Avoid granting administrator privileges “just in case.”
-
Configure the system firewall (host-based firewall): Block all incoming and outgoing traffic, except for those ports and protocols that are explicitly required for the application to run on the server.
-
Enable and centralize logging: Set up detailed logging of security events and send logs to the central SIEM system.
How to effectively secure network devices such as routers and switches?
Network devices such as routers and switches are the backbone of corporate communications. Compromising them can give an attacker tremendous opportunities, such as eavesdropping on traffic, rerouting connections or paralyzing the entire network. Hardening these devices is as important as securing servers.
The absolute bottom line is to change the default administrator credentials. Every network device comes with a factory default, well-known login and password. Leaving them out is an unambiguous invitation to attackers. Unique, complex passwords should be created for all devices.
Another critical step is to secure management interfaces. Unsafe, unencrypted protocols such as Telnet or HTTP should be disabled, and only secure, encrypted protocols such as SSH (Secure Shell) and HTTPS should be allowed to manage the device. Access to the management interface should be further restricted via access control lists (ACLs) to only trusted IP addresses of administrators’ workstations. If possible, management should take place on a separate, isolated network (management VLAN).
Other key measures include disabling unused ports on switches to prevent unauthorized devices from connecting to the network, and regular firmware updates that install patches for known vulnerabilities.
Basic Hardening Checklist for Server and Network Device
| Area | Key Action | Why is this important? |
|---|---|---|
| Password Management | Change all default passwords. Implement a policy of complexity and regular password changes. | Default passwords are publicly known and are the easiest attack vector. |
| Services and Ports | Turn off all unused services, applications and network ports. | Every running service is a potential “hole” and entry point for an attacker. Minimization = risk reduction. |
| Correction Management | Implement a process for installing security patches on a regular and timely basis. | Unpatched systems are susceptible to known exploits that are massively exploited by hackers. |
| Logging and Monitoring | Enable detailed event logging and send logs to a central system (such as SIEM). | Without logs, it is virtually impossible to detect an intrusion and analyze its progress. |
| Management Protocols | Disable unsecured protocols (Telnet, HTTP, FTP) and use only their encrypted counterparts (SSH, HTTPS, SFTP). | Unencrypted protocols make it easy to eavesdrop on and steal passwords sent over the network. |
What are standards and benchmarks, such as CIS Benchmarks, and how do they help in hardening?
The process of hardening can seem complicated, and the number of possible settings to change in modern operating systems goes into the thousands. Fortunately, there is no need to reinvent the wheel. There are internationally recognized, publicly available standards and benchmarks that provide detailed, ready-to-implement guidelines.
One of the most respected and widely used sets of such guidelines are the CIS Benchmarks, published by the Center for Internet Security (CIS). CIS is a non-profit organization that, in collaboration with a global community of experts, creates and maintains detailed hardening guides for more than 100 different technologies - from operating systems (Windows, Linux) to server software (Apache, Nginx) to cloud platforms (AWS, Azure) and network appliances.
Each CIS benchmark is a several-hundred-page document that describes step-by-step how a particular system should be configured to achieve optimal security. Each recommendation includes a detailed description of the risks, implementation instructions and the potential impact on system performance. Using CIS Benchmarks allows you to structure your hardening process, ensures its consistency and gives you confidence that your configuration is in line with globally recognized best practices.
How does nFlo help organizations implement a comprehensive hardening strategy?
At nFlo, we see hardening as the absolute foundation of any mature cyber security strategy. It’s a proactive investment that prevents incidents before an attack is even attempted. However, we understand that in complex IT environments, systematically and consistently implementing hardening principles is a huge operational challenge.
Our services begin with a configuration audit (Configuration Review). Our team of experts performs a detailed analysis of key elements of the client’s infrastructure - servers, network devices, firewalls - comparing their current configuration with recognized industry standards, such as CIS Benchmarks. The result of the audit is a precise report that identifies all deviations from best practices and provides specific remedial recommendations.
However, we do not stop at just auditing. Our engineering team actively supports customers in the process of implementing hardening recommendations. We help create secure server baseline images (“golden images”), reconfigure network devices, and automate the hardening process using tools such as Ansible or Active Directory GPO policies. As part of our vulnerability management services, we integrate the hardening process with continuous scanning and patching, creating a consistent security lifecycle for the entire infrastructure.
Related Terms
Learn key terms related to this article in our cybersecurity glossary:
- Network Security — Network security is a set of practices, technologies, and strategies aimed at…
- Cybersecurity — Cybersecurity is a collection of techniques, processes, and practices used to…
- Firewall — A firewall, also known as a network firewall or security barrier, is a security…
- Cybersecurity Incident Management — Cybersecurity incident management is the process of identifying, analyzing,…
- Security Architecture — Security architecture is a comprehensive approach to designing, implementing,…
Learn More
Explore related articles in our knowledge base:
- LAN and WAN: Build a secure and efficient IT infrastructure. A complete guide for your business
- Physical security testing - effective infrastructure protection
- Who Does the National Cybersecurity System Cover? Entities, Operators, Providers and Authorities
- Smart Grid security: How to protect power grids in the digital age?
- What is Starlink and how to use it securely in a company’s infrastructure?
Explore Our Services
Need cybersecurity support? Check out:
- Security Audits - comprehensive security assessment
- Penetration Testing - identify vulnerabilities in your infrastructure
- SOC as a Service - 24/7 security monitoring
